Dubai Building Code (2021)

Dubai Building Code

Part G: Incoming utilities

G 49

Table G.14 Typical details of maximum current on transformer with chiller/motor loads

DETAILS OF MAXIMUM CURRENT ON TRANSFORMER WITH CHILLER/MOTOR LOADS

PROJECT:

OWNER:

PLOT NUMBER:

AREA:

LV Panel No.:

Rating:

Sr. No.

Type of load

(chiller, motor, etc.)

No. of compressors

per chiller

Starting current of

one compressor/

motor

Full load current with all

compressors/motors running

+ other loads

(A)

Max. current when largest compressor

starts + all other compressors/ motors

and other loads running

(A)

Remarks

(model no., make, type

of starter, etc.)

Total

Dubai Building Code

Part G: Incoming utilities

G 50

Table G.15 gives the maximum demand permitted at an

MDB connected to DEWA’s supply

feeder/transformer for the distribution of normal

residential and commercial premises without

connecting large motor loads.

Item

Feeder/transformer rating (A)

Load (kW)

60 A – feeder

100 A – feeder

125 A – feeder

160 A – feeder

200 A – feeder

100

300 A – feeder

150

400 A – feeder

200

1,000 kVA transformer

800

1,500 kVA transformer

1,200

Item

Transformer rating (kVA)

Load (kW)

1,500 kVA transformer

950

1,000 kVA transformer

650

Table G.15

Limit of maximum demand loads

Table G.16

Limit of maximum demand air conditioning loads

DEWA transformers supplying motors and air

conditioners (maximum individual loads not exceeding

100 kW) shall be limited to the connected loads given

in Table G.16.

Where DEWA transformers supply motors and air

conditioners whose individual loads exceed 100 kW,

the maximum TCL shall be subject to approval by

DEWA.
To ensure the safety of the transformers and

the equipment, approval takes into account the

equipment’s technical specification, including:

a)  the rating;
b)  the type of starters;
c)  the maximum starting current;
d)  the number of compressors/motors; and
e)  its stages of operation.
The overload protective device/incomer circuit

breaker in the LV panels/MDBs shall be set at the

corresponding design current.
Other methods of establishing maximum demand are

permitted, where calculated by a qualified electrical

Engineer with a suitable degree of knowledge and

experience of the diverse applications of a particular

installation. The design method and proposed diversity

at each level of the distribution shall be submitted to

DEWA for approval. They shall also be clearly indicated

in the design drawings and schedules submitted to

DEWA.

G.4.17 Design criteria for the installation of

conduits, trunking, trays and accessories

G.4.17.1 Trunking and conduits

Trunking and conduits shall be selected to meet the

requirements of G.4.11.
As far as possible, trunking and conduit runs from

electrical switchrooms to individual consumer DBs

shall be routed only within common electrical service

routes and riser ducts.

Long trunking and conduit runs from electrical

switchrooms located on the ground floor to consumer

DBs located on upper floors shall not be installed

unless unavoidable. Where armoured cables are used,

they shall be installed in cable trays.
Cable trunking may be used for housing single core

LSF cables where the installation of conduits is difficult

due to space limitations.
Surface exposed trunking and conduit installations

shall, as far as possible, have straight runs with

branches at right angles only.
Draw-in boxes shall be provided in all straight conduit

runs exceeding 15 m. Conduit runs having 90º bends

shall be provided with draw-in boxes for every two

bends.
Trunking and conduit shall be completely installed

before any cable is drawn in.

Dubai Building Code

Part G: Incoming utilities

G 51

Draw-wires shall be provided in all concealed conduits (and ducts) with the ends

left free at the outlet boxes for pulling the wiring cables. Permitted cable routes for

concealed cables are illustrated in Figure G.19.

Figure G.19

Permitted cable routes for concealed cables within walls with a depth of less than

50 mm depth. (© Institution of Engineering and Technology. Figure based on Figure 2.3.3 in Institution of

Engineering and Technology, 2018. Electrician's guide to the building regulations

[Ref. G.2]

)

Key

01: No protection needed

02: Protection required unless depth greater than 50 mm

All the trunking and conduit runs shall be free from sharp edges and burrs

throughout their lengths. Suitable grommets and bushes shall be provided at the

terminal outlets.
Trunking and conduit runs shall be supported at regular intervals (see Table G.17 to

Table G.19).

Method of installation

Spacing of support (mm)
Steel

Rigid PVC

Horizontal

1,500

1,000

Vertical

1,800

1,200

Method of installation

Spacing of support (mm)
Steel

Rigid PVC

Horizontal

1,200

1,000

Vertical

1,500

1,200

Method of installation

Spacing of support (mm)
Overall diameter

20 mm to 40 mm

Overall diameter

>40 mm

Horizontal

350

600

Vertical

600

800

Table G.17

Trunking – Maximum spacing of clips, cleats, saddles or supports

Table G.18

Conduit – Maximum spacing of clips, cleats, saddles or supports

Table G.19

Armoured cables – Maximum spacing of clips, cleats, saddles or supports

Dubai Building Code

Part G: Incoming utilities

G 52

Entries to trunking shall be placed to prevent the

ingress of water and all dead ends shall be closed. Only

unbroken lengths of trunking shall be used for crossing

partitions and walls.

Where cable trunking passes through walls, floors or

other barriers, it shall be provided with a continuous

cover.

Where cable trunking penetrates fire resistance

rated floors, walls, partitions or ceilings, the openings

remaining after passage of the trunking systems shall

be sealed with an approved fire stopping system in

accordance with Section 3, Ch. 1 of UAE

FLSC

[Ref. G.1]

The trunking shall be provided with separate

compartments for the different types of circuits in the

following situations:
a) where a common cable trunking is used for housing

both power and communication circuits; or

b) for housing circuits operating at different voltages.
All bends, tees and other accessories of cable trunking

shall be of substantial sections and of the same quality

as the trunking itself.
The different sections of trunking shall be bonded by

copper links. Trunking shall not be used as ECC.
The minimum internal radius of any bend or elbow

fitting in a conduit shall be 2.5 times the diameter of

the conduit, as shown in Figure G.20.

Figure G.20 Minimum internal radius of conduit elbow fitting

All terminal and intermediate ends of PVC conduits

shall be firmly secured with suitable adhesives as

recommended by the manufacturer.
Circuit wires shall be bunched and installed in vertical

trunking runs. They shall be clamped/secured within

the trunking at regular intervals not exceeding 2 m, and

at the terminal ends.
Standard conduit boxes, draw-in boxes and mounting

boxes of light fittings and appliances shall be fixed

to the building structure independently of the wiring

conduits.

All exposed threads, tool-marks or visible damage to

the protective finish of the steel trunking and conduits

shall be coated with zinc rich paint immediately after

installation.
Suitable expansion couplers shall be provided in all

trunking and conduit runs at the expansion joints in

the building structure. They shall also be provided at

regular intervals in all runs exceeding 7 m in length or

as recommended by the manufacturer.
Suitable purpose-made boxes with adaptors, ceiling

roses, etc. shall be provided at all individual outlet

points of the wiring installations.

Light fittings used to house tungsten filament and

halogen lamps shall be segregated protected by PVC

sheathing and terminal outlet boxes such as to prevent

degradation due to the associated high temperatures.
Conduit runs concealed within the building structure

shall be provided with not less than 10 mm of screed

cover.
When the trunking and conduit runs are installed

with chases in the building structure, they shall be

firmly fixed at regular intervals in accordance with the

manufacturer’s recommendations, using purpose-made

crimpers and/or saddles.

The standard conduit boxes, draw-in boxes, floor-

outlet boxes, etc. shall be installed with the cover/lid

flush with the outer finish of the building structure

(see BS 4662, BS 5733, BS EN 61535).

Dubai Building Code

Part G: Incoming utilities

G 53

Only flush type switches, socket outlets and

accessories shall be used for concealed wiring.

Where conduit and or conduit fittings are attached

to equipment, smooth bore male brass brushes and

flanged coupling shall be used.

Except where provision is made for fastening, conduits

shall be saddled to the structure of the building in

accordance with the following:
1) within 150 mm of each terminal angle box, bend

or other conduit fittings;

2) at maximum intervals of 1.5 m from couplings and

through fittings.

Through type draw boxes shall be counted as part of a

straight run conduit.
Non-metallic conduits shall not be used in the

following locations and circumstances:
i) where the conduit is exposed to outside ambient

temperatures;

ii) where the conduit is at risk of being affected

by chemicals which cause deterioration in its

construction;

iii)  plant rooms;
iv)  elevator motor rooms;
v)  elevator shafts.
All conduit accessories shall be factory-made sections

and of the same quality as the conduit itself.

G.4.17.2

Flexible conduits

Flexible conduits shall not be used for complete fixed

wiring installations. They shall only be used as and

where permitted.

A flexible conduit run shall be not more than 2.5 m in

length.

Metallic flexible conduits may be used for connecting

electrical motors and other equipment to the fixed

wiring, subject to adjustment of position and vibration.

Flexible conduits shall only be run exposed and shall

be so positioned that they are not susceptible to

mechanical damage. Wherever necessary, flexible

conduits shall be supported in accordance with the

manufacturer’s recommendations.

The end of flexible conduits shall be securely anchored

to the fixed conduit or equipment to which it is

attached. Approved flexible conduit adaptors shall be

used that maintain effective mechanical continuity

without distorting the conduit.

Flexible conduit shall not be used as part of the

earth conductor. A separate earth conductor shall

be installed to meet the same requirements for rigid

conduit installation.

G.4.17.3 Cable trays

Trays for supporting cables shall be used in

warehouses, industrial plant and equipment rooms,

cable trenches, shafts in buildings, etc.
The type and material of the cable trays shall be

selected to suit individual site locations and shall meet

the relevant requirements specified in G.4.11.

The cable trays shall be supported at regular intervals

with purpose-made supports (see Table G.19).
Cable trays installed in outdoor locations and in

locations where cables are exposed to the sun shall

be provided with sun-shade covers. Covers shall be

secured to the trays, and adequate ventilation provided,

in accordance with the manufacturer’s instructions.
Cables shall be fastened securely by purpose-made

clips, cleats or saddles and spaced as shown in

Table G.19.
Cable ties shall not be used to support multicore cables

installed on cable trays that are fitted vertically.

Cable trays shall not be used in locations where they

are likely to be subjected to severe physical damage.

Sufficient space shall be provided and maintained

around cable trays to permit access for installing and

maintaining the cables without causing unnecessary

damage. Vertical clearance above the tray shall be

not less than 1.5 times the height of the tray, or

as given in the cable and cable tray manufacturer’s

recommendations.

Dubai Building Code

Part G: Incoming utilities

G 54

Cable trays shall be installed as complete systems with

bends and other accessories. Each run of cable trays

shall be completed before the installation of cables. All

sharp edges, burrs and projection shall be removed,

and the tray shall be finished smooth to prevent injury

to cables.
Metallic cable trays shall be bonded together using

copper links, but shall not be used as an ECC.
Cable trays shall be installed in such a way as to

provide ease of access to cables through the route.

Where cable trays penetrate fire rated floors, walls,

partitions or ceilings, the openings remaining after

passage of the wiring systems shall be sealed with

an approved fire stopping system in accordance with

Section 3, Ch. 1 of UAE FLSC

[Ref. G.1]

G.4.18 Design criteria for the installation

of cables, equipment, accessories and wiring

systems

G.4.18.1 Armoured cables

Armoured cables shall be installed in one of the

following ways:
a)  directly buried in the ground;
b)  drawn through ducts;
c)  laid in concrete trenches;
d)  cleated to a wall;
e)  mounted on cable trays.
Cables shall be installed and used in association with

other equipment in accordance with BS 7671. In

environments or installations not described within the

DBC, the appropriate regulations and standards shall

be observed.
The current-carrying capacity of cables shall be

determined after applying suitable correction factors

based on the installation method of the cables.
Cables shall be selected ensuring voltage drops within

the limit described in G.4.7.3.
Only armoured cables shall be used for underground

installations. Precautions shall be taken to avoid

mechanical damage to the cables before and during

installation. Cables shall be laid as shown in

Figure G.21. Where protective covers are required, they

shall be centred over the cables, throughout

their length.

Figure G.21

Typical armoured cable installation below ground

Key

01: Ground

02: Warning tape at 300 mm below ground

03: 50 mm overlap on either side

04: Armoured cable at 900 mm below ground

05: 150 mm impervious soil layer

Dubai Building Code

Part G: Incoming utilities

G 55

Where cables pass underneath driveways or roads,

PVC-U ducts shall be provided with heavy duty (HD)

manhole covers.
Cable routes shall be marked by cable route markers/

marking tape, placed at maximum intervals of

10 m along straight runs and 2 m at deviations.

Route markers shall indicate the voltage level in Arabic

and English, as shown in Figure G.22.

Figure G.23

Cable bending radius

No joints shall be included in any cable runs in the

consumer’s fixed wiring installation.
Where busways penetrate fire rated floors, walls,

partitions or ceilings, the openings remaining after

passage of the wiring systems shall be sealed with

an approved fire stopping system in accordance with

Section 3, Ch. 1 of UAE FLSC

[Ref. G.1]

Cable glands used for armoured cables shall be of brass

compression type, conforming to BS 6121, with earth

tags and PVC shroud.
All terminations of cable conductors shall be

mechanically and electrically sound. Terminations shall

be made using a terminal or compression type socket/

lug, approved by DEWA. Terminations shall not impose

any mechanical strain on the terminal or socket/lug.
Separate ECCs shall be installed and terminated for

each feeder/circuit, as specified in G.4.19.

Single core cable shall be arranged in trefoil formation.

Non-ferrous cable gland plate shall be used for

termination of single core armoured cables.

The armour shall be earthed.
No cables shall run in an elevator or hoist shaft unless

the cables are part of the elevator/hoist installation.

Figure G.22

Typical cable route marker (DEWA)

Heavy duty conduit shall be provided for motor

connections, external applications and locations subject

to vibration, risk of mechanical damage or exposure to

moisture.

Cables shall be installed on cable trays at specific

locations and as stipulated in G.4.11.
In the event of crossing or proximity of underground

telecommunication cables and underground power

cables, a minimum vertical clearance of 100 mm shall

be maintained.

For cables in fixed wiring installations, the internal

radius of the bend shall be not less than eight times

the cable diameter (see Figure G.23).

Dubai Building Code

Part G: Incoming utilities

G 56

G.4.18.2 Distribution boards

All DBs shall be installed in locations which are

accessible at all times for operation, testing, inspection,

maintenance and repair.

MDBs, SMDBs or final DBs shall not be installed in the

following locations:
a)  bathrooms and toilets;
b)  damp or wet locations;
c)  bedrooms;
d)  kitchens;
e)  above sinks;
f)  store rooms;
g)  rooms with an ambient temperature exceeding the

ambient design conditions of the equipment;

h) dangerous or hazardous locations;
i) below any staircase.

All MDBs, SMDBs or final DBs shall be selected and

designed in accordance with G.4.12.
DBs shall incorporate means for isolation of mains

supply in the form of either a circuit breaker or an

incomer isolator, as applicable.
Every circuit breaker or fuse within the DB shall be

identified and labelled to indicate the apparatus or

circuit it controls. Table G.12 and Table G.13 show

typical single-phase and three-phase DB schedules.

Each final DB shall supply only the circuits in the floor

area where the DB is located, as shown in Figure G.24,

except for applications such as staircase and common

corridor lighting in high-rise buildings.

Figure G.24

Indicative electrical distribution diagram

Figure G.25

Maximum DB mounting height diagram

Key

01: DB

02: SMDB

Key

01: DB

02: FFL

In multi-consumer installations, each consumer’s DBs

shall be installed within the respective consumer’s

premises (e.g. retail unit, apartments, etc.) and shall be

near to the entrance of the premises.
Incoming supply cable installed to any DB shall be

segregated and identified from the outgoing circuit

cables/wiring.

All DBs shall be installed flush or surface mounted at a

maximum height of 2 m to the top of the DB as shown

in Figure G.25.
All LV panels of 1,600 A and above shall be of form

4 type.

≤

2 m

Dubai Building Code

Part G: Incoming utilities

G 57

500 - 1,800

G.4.18.3

Busbar trunking systems (busways/bus

risers)

Busways shall be installed only where adequate access

is available for inspection and repair throughout their

entire length.
The design, manufacture, testing and performance of

the busbar trunking system shall be in accordance with

BS EN 61439. The IP rating shall be selected based on

the location, as described in BS EN 60529.
Each piece of busbar trunking shall be subject to the

following factory tests:
a) 3.5 kV dielectric test for 4 s;
b) 1,000 V Megger test in accordance with BS 7671.

Test certificates for these tests shall be produced

during DEWA inspection.
The busbars shall be totally enclosed in an

unventilated, low impedance sandwich design. The

busbar trunking shall be sandwiched throughout its

entire length and shall not be flared at tap-points.

Onsite, each piece and run of busbar trunking shall be

Megger tested at 1,000 V before and after installation.
Busbar risers proposed for installation in high-rise

buildings shall be designed in such a way as to ensure

reliability of power supply. In the event of outage of the

respective busbar riser, not more than 12 floors shall

be interrupted.

Connections to switchgear shall have flanged end units

of specific design and shall be manufactured by the

busbar trunking manufacturer.
The busbar trunking shall be aligned and securely

fixed at centres of not more than 1.5 m or as

recommended by the manufacturer. The busbar

trunking manufacturer shall supply galvanized fixing

brackets, comprising hanger clamp, fixing channel and

damping screw, as means of support to take the weight

of the busbar. Additional supports shall be provided

where required and as recommended by the trunking

manufacturer.
The complete busbar trunking system shall be of the

type, size and location indicated in the DEWA approved

drawings.
The busbar shall carry its rated current without

exceeding 55 ºC (or an ambient temperature of 50 ºC

at 90% relative humidity) in any plane without

de-rating and without affecting the DEWA power

supply requirements.
Where a busbar trunking system is installed on the

supply side of any DEWA kWh metering, provision for

sealing by DEWA shall be made as specified in G.4.5.

The phase busbar, neutral bar and earth bar shall be of

copper, identified by colour as given in Table G.8. The

neutral bar shall be of the same cross-section as the

phase busbar.

ECCs and equipotential bonding shall be provided as

specified in G.4.19.
Where the busway passes through fire rated floors,

walls, partitions or ceilings, the openings remaining

after passage of the wiring systems shall be sealed

with an approved fire stopping system in accordance

with Section 3, Ch. 1 of UAE FLSC

[Ref. G.1]

Tap-off units installed in a busbar riser at each floor

level shall be at the height shown in Figure G.26. The

tap-off units shall have adequate access for operation,

maintenance and replacement.

Figure G.26

Busbar tap-off mounting height requirement

Key

01: Tap off

02: MDB/SMDB

03: Busbar

Dubai Building Code

Part G: Incoming utilities

G 58

G.4.18.4 Segregation of circuits, phases and

wiring systems

All wiring and accessories shall be selected and

installed to suit individual locations. They shall conform

to G.4.11 and the following requirements.
Circuits from different DBs shall not be installed in a

common conduit or trunking.
The circuit wires of individual categories and of

different voltage grades shall be installed in separate

conduits, or segregated with barriers where installed in

the same trunking run.
The circuit wires of individual categories (such as

lighting, power and emergency) shall be segregated

with barriers in trunking runs or installed in separate

conduits.
Where residential premised are supplied with a

three-phase supply, the light fittings, socket outlets,

water heaters, cookers and other single-phase

apparatus in any room shall not be connected to

more than one phase, unless this is unavoidable. If

connection to more than one phase cannot be avoided,

a minimum distance of 2 m shall be maintained

between outlets, accessories or appliances connected

to different phases.

Where a switch box contains more than one phase,

for group switching, approved switch boxes with phase

barriers shall be used and labelled to indicate that

400 V is present in the back box. All circuit wires shall

be identified by colour as shown in Table G.8.

Where a wiring system is in close proximity to

non-electrical services, the wiring system shall be

segregated and protected against hazards that are

likely to arise from the presence of the other service(s)

in normal use. Provision shall be made for safe and

adequate access to all parts of the wiring system which

might require inspection, maintenance or replacement.

Switches controlling light fittings, water heaters, etc.

shall not be installed in bathrooms. In kitchens and

other areas where water is regularly used, switches

shall not be mounted within 2 m of any water tap, wash

basin or sink where possible. If there is insufficient

space to allow for this, ceiling mounted, insulated,

cord-operated switches shall be used.
Socket outlets shall not be installed in bathrooms.
Where luminaires have a track system, this shall

conform to BS EN 60570.

Dubai Building Code

Part G: Incoming utilities

G 59

1,250

450

150

Figure G.27

Typical mounting heights of electrical accessories

Figure G.28

Typical electrical warning label

G.4.18.6

Identification labels and notices

All sections of the consumer installation at the DBs

shall be provided with identification labels to indicate

the location and purpose of each protection device,

piece of connected equipment and circuit. Instructions

or caution notices for correct operation shall also be

provided where necessary. All labels shall be in both

English and Arabic as shown in Figure G.28. Font sizes

shall be chosen to suit the individual application.

G.4.18.5 Mounting heights of accessories

Accessories (as described in G.4.13) shall be mounted

as follows (and as shown in Figure G.27).

a) All lighting switches, DP switches of air

conditioning units and water heaters, ceiling fan

regulators, shaver socket outlets, etc., provided as

part of the electrical installation shall be mounted

1.25 m above the finished floor level.

b) 13 A switched socket outlets used for general

purpose shall be installed at 450 mm above the

finished floor level. 13 A switched socket outlets

provided in kitchens shall be installed 150 mm

above the worktop.

All switches shall be mounted in readily accessible

positions.

Dubai Building Code

Part G: Incoming utilities

G 60

G.4.19 Earthing and earth leakage

protection

G.4.19.1 General

Earthing systems shall be designed and installed in

such a way that they remain safe and do not endanger

the health and safety of persons or their surroundings.

Every consumer installation shall be provided with

a separate earthing system within the plot limits,

installed and maintained by the consumer.
An earth system shall remain effective throughout the

life of the plant. It is difficult in many cases to perform

of continuity checks after installation; the system shall

therefore be robust and protected from mechanical

damage and corrosion where necessary.
Each consumer’s earthing system shall comprise

the earth electrode(s) main earth lead conductor

connected between the earth electrode(s) and the

consumer’s main earthing terminal(s) or earth busbar.
ECCs shall be provided for every outgoing circuit from

the MDB, SMDB and final DBs, equipotential bonding

of all metalwork and exposed conductive parts and

enclosures, etc. Guidance is available in BS 7430,

BS EN 50522 and IEC 60364.
Selection of the earthing conductor material shall

be based on its compatibility with the material of

the earth electrode. For a conductor installed in the

ground, the corrosive effect of the soil shall also be

taken into account.

The consumer’s earthing system shall be connected

to the DEWA earthing system [either the incoming

supply cable armour or the earth continuity conductor

(ECC), as approved by DEWA].

The following shall have separate earthing networks

and shall not be connected to the main electrical

earthing system:
a) MV networks;
b)

LV networks;

Extra LV networks;

d) private generators;
e) lightning protection systems.

The earthing system shall be of low electrical

resistance, good corrosion resistance and able to

dissipate high fault current repeatedly.
The consumer main earthing connection shall be

a TN-S system (see Figure G.29). The exposed

conductive parts of all the electrical equipment of the

installation shall be connected by circuit ECCs to the

main earthing terminal. The earth fault loop impedance

shall be sufficiently low for the protective device (fuse,

circuit breaker, RCD) to operate in the required time in

the event of a fault to earth.

Figure G.29 Typical TN-S earthing arrangement (© British Standards Institute. Figure extracted from BS 7671:2018. Permission to reproduce extracts

from British Standards is granted by BSI Standards Limited (BSI). No other use of this material is permitted).

Key

01: Source of energy

02: Protective conductor (PE)

03: Consumers’ installations

04: Source earth

05: Equipment in installation

06: Exposed-conductive-parts

Dubai Building Code

Part G: Incoming utilities

G 61

The neutral and earth conductors shall be kept

separate. They shall not be connected together at

the main earth terminal or at any other point in the

consumer’s installation.
Where several installations have individual earthing

arrangements, any common ECC shall be capable of

either:
1)

carrying the maximum fault current likely to flow

through them; or

2) being earthed within one installation only and

insulated from the earthing arrangements of any

other installation.

Foundation metalwork in concrete may be used as

a ready made and effective earth electrode. The

total electrode area formed by the underground

metalwork of a large structure can be used to provide

an earth resistance lower than that obtainable by

other methods. It is important that consideration is

given to the possibility of corrosion of the metalwork

reinforcement. The products of corrosion occupy a

greater volume than the original metal, and cracking

might occur.
Continuous earth leakage currents shall be mitigated

by the designer of the electrical system.

NOTE: Some earth leakage currents might be

incompatible with other buried metalwork, including

other types of earth electrode to which foundation

metalwork might be bonded, such that it might be

necessary to consider the need for cathodic protection.

Damage to the concrete in the form of cracking, due to

arcing or the rapid evaporation of moisture, can occur

where the long-term duration earth fault currents

exceed the carrying capability of the electrode. This

situation is unlikely to arise if the electrode has a

resistance sufficiently low to avoid dangerous voltages

to earth. Where, in structures made of bolted sections,

the electrical continuity of the structural joints cannot

be relied upon to form permanent and reliable earth

bonds, bonding loops across these joints shall be

installed.
Water mains shall not be used for earthing purposes.

Metal pipes (e.g. for gas, oil, compressed air or

drainage) carrying other services shall only be bonded

to the protective conductors and not used for the sole

means of earthing.
Earth electrodes shall not be installed at a distance

from a metal fence less than the buried depth of the

electrode, unless they are used for earthing that fence.

This is to avoid the possibility of the fence becoming

live and thus dangerous at points remote from the

substation, or alternatively giving rise to danger within

the resistance area of the electrode by introducing a

good connection with the general mass of the earth.

G.4.19.2 Consumer’s main earth electrode

A minimum of one main earth electrode shall be

provided for each incoming point of supply/consumer’s

MDB, within the consumer’s premises. For installations

with a main incomer of 200 A and above, a minimum of

two earth pits shall be provided.
The earthing systems shall consist of copper

conductors or steel rods (austenitic steel or copper

clad) of appropriate dimensions, set with a driving

pin and head driven to a minimum depth of 3 m. The

earth electrode shall be installed inside a 300 mm ×

300 mm × 300 mm earth pit with inspection cover.

The connection of the earthing conductor to the earth

electrode or other means of earthing shall be made

using compound filled, encapsulated or substantial

clamps of non-ferrous material.

NOTE: Uncoated buried copper is electro-positive

to uncoated buried steel. When interconnected by

a current-carrying conductor, these metals form

an electrochemical cell that can cause accelerated

corrosion of steel.

The consumer’s main earth electrode shall be installed

within 1.5 m of the MDB. Where more than one earth

electrode is installed within the premises, they shall be

spaced not less than 6 m apart. Load centres located

laterally 50 m or more from the MDBs might require

additional backup earthing.

Dubai Building Code

Part G: Incoming utilities

G 62

Apart from the risk of corrosion to the earthing

system, the chemical treatment of soil has

environmental implications and is not a long-term

solution to meet a specified level of resistance.

Coke breeze shall not be used due to its highly

corrosive nature.

For each incoming DEWA supply/MDB, the main earth

electrode resistance shall not exceed 1 Ω.

The resistance from any point of the earth continuity

conductor (ECC) to the main earth electrode shall not

exceed 0.5 Ω.

The consumer’s earth electrode resistance and the

continuity of ECCs shall be periodically checked and

maintained to ensure consumer safety as outlined in

BS 4444.

Lightning protection earthing shall be separate from

the earthing of the incoming DEWA supply/MDBs. A

minimum distance of 7 m shall be maintained between

the earthing inspection pits.

G.4.19.3

Earth continuity conductor (ECC)

Every circuit in the MDBs, SMDBs and final DBs shall

be provided with a separate green and yellow (G/Y)

LSF insulated copper ECC. The minimum size of ECCs

shall be selected as specified in Table G.20.

Cross-sectional

area of phase/

neutral conductor

(S) (mm

)

Minimum cross-

sectional area of

ECC (G/Y LSF

insulated copper

conductors) (mm

)

Minimum cross-

sectional area

of equipotential

bonding

conductors (mm

)

S ≤ 16

S/2
(not less than 6)

16 < S < 35

S > 35

S/2

S/4
(need not exceed

25)

Table G.20 Minimum size of earth continuity cables (ECC)

ECCs shall be terminated with tinned copper lugs at

both ends, on purpose-made earth terminals at:
a) electrical equipment, apparatus and distribution

switch gear;

light fittings;

c) mounting boxes of switches and socket outlets.
All busbar risers installed for electrical distribution in

high-rise buildings and other consumer installations

shall incorporate an appropriately sized ECC either

within, or run separately along, the riser. BS 7430 gives

guidance on earthing and ECCs.

Joints shall be made such that their current-carrying

capacity is not less than that of the conduit itself.

Joints shall also have the same insulation, mechanical

strength and protection properties as those of the

wiring system or conduit of which they are part.

ECCs shall be covered with green and yellow LFC

insulation and terminated with purpose-made lugs or

fixings.

Where associated with circuits, ECCs shall be labelled

at their termination points with circuit identification

numbers.
Circuit ECCs shall run alongside the associated phase

and neutral conductor.
The following shall not be used as an ECC:
1) gas pipes;
2) oil pipes;
3)

metallic conduit, support wires or other flexible

metallic parts;

4) construction elements other than metalwork as

described in G.4.19.1.

ECCs shall be protected against mechanical and

chemical deterioration and electrodynamics effects in

accordance with the manufacturer’s requirements.

Dubai Building Code

Part G: Incoming utilities

G 63

Where two ECCs are used, the ends of the ECC shall

be terminated independently of each other at all

connection points throughout the circuit, the DBs,

junction boxes and socket outlets. To achieve this, an

accessory shall be provided with two separate earth

terminals.
Where the cable incorporates metallic armouring, this

shall be clamped to the cable gland. The main earth

conductors shall be placed such that the metallic cable

sheaths can be reliable and readily connected to it by

bonds made to the cable gland.
Earthing conductors shall be accessible for the

connection of any detachable earthing devices used

with the electrical equipment.

G.4.19.4 Earth leakage protection

Earth leakage protection shall be designed and

incorporated in consumer installations in accordance

with BS EN 61140 and IEC 61140.

The ELCBs/RCCBs shall generally conform to

BS EN 61008-1 and BS EN 61009-1. Recommended

values of operating current of ELCBs/RCCBs are

specified in Table G.21, though the designer shall verify

with the manufacturer’s recommendations.

Sr. No. Circuit/equipment/apparatus

Rated operating

current (mA)

13 A switched socket outlets

Water heater/coolers/dishwashers

Refrigerator/washing machine and

similar apparatus

Domestic water pumps

Jacuzzi pumps

Under water lighting

15 A switched socket outlets

(general purpose)

General lighting

30/100

Flood lighting

100/300

Window/split type air conditioner

100

Fan coil/AHU/VAV

100

Package type air-conditioning unit

100/300

Chiller

100/500/1,000

Irrigation pump

100

Electric cooker

100

Industrial machine

100/300

Elevators/escalators/hoist

300/500

Neon sign

300

Table G.21

Recommended value of operating current for ELCB/RCCB in

consumer installations

NOTE 1: Grouping of circuits under one ELCB/RCCB

is permitted for lighting circuits, general purpose

switched socket outlets, single-phase equipment/

appliances, etc. The maximum number of circuits

proposed under each group should be selected taking

into account the building type and the possible

interruptions.
NOTE 2: Wherever an uninterruptable power supply

is required to provide power to equipment and

circuits as part of a fire protection system (such as

fire pump, jockey pump, sump pump, sprinkler pump,

pressurization pump, smoke extract fans), a suitable

earth leakage detection system with indication and/or

alarm should be provided.

For industrial installations that are designed with

common operating systems for plant and machinery,

the earth leakage protection shall be selected taking

into account the safety and operational requirements.

Operation of the ELCBs/RCCBs, earth leakage

detection system, etc. shall be periodically checked

and tested in accordance with the manufacturer’s

recommendations to ensure consumer safety.
Earth leakage sensors/relays with alarm/indicators

shall be provided for fire pumps, jockey pumps,

submersible pumps, sump pumps, or other essential

circuit/equipment with sensor settings that allow

for pre-fault warning notification and fault warning

notification.

Dubai Building Code

Part G: Incoming utilities

G 64

G.4.19.5 Equipotential bonding

All metalwork of the consumer’s installation, other than current-carrying parts, shall

be provided with equipotential bonding conductors as shown in Figure G.30. This

shall include, but is not limited to:
a)  cable armour;
b)  metal conduits;
c)  metal cable tray/trunking sections;
d)  metal accessory boxes;
e)  exposed metalworks of consumers’ appliances;
f)  apparatus;
g)  equipment;
h)  machines;
i)  building structures;
j)  metallic enclosures and parts;
k)  metal water pipes.
The cross-sectional area of equipotential bonding conductors shall be selected using

Table G.20.
A main protective bonding conductor shall have a minimum cross-sectional area

not less than half the cross-sectional area required for ECC of the installation, and

not less than 6 mm

. A maximum cross-sectional area of 25 mm

is sufficient if

the bonding conductor is of copper or a cross sectional area affording equivalent

conductance in other materials.
The equipotential bonding conductors shall be connected to the main earthing

terminal within the consumer’s wiring installations. The continuity shall be tested and

maintained by the consumer.

Figure G.30

Typical example of main equipotential bonding of services (© Institution of

Engineering and Technology. Figure based on Figure 5.6 in Guidance Note 8: Earthing and

Bonding

[Ref. G.3]

Key

01: Other extraneous conductive part

02: Water installation pipe

03: Circuit protective conductors

04: Gas installation pipe

05: Main protective bonding conductors

06: Earthing conductor

07: Means of earthing

Dubai Building Code

Part G: Incoming utilities

G 65

G.4.20 Power factor correction, harmonic

and undervoltage (UV) relays

G.4.20.1 PF correction

The PF of every consumer installation shall be within

the range of 0.9 lagging and unity (recommended value

0.95 lagging).
All air-conditioning units/plants/equipment, machines,

motors, light fittings with discharge lamps/mercury

vapour/sodium vapour/fluorescent tubes, etc., shall

be provided with capacitors or other approved means

to achieve and maintain a PF of 0.95 lagging or above,

throughout their normal working range.

For commercial premises that require DEWA service

feeders of 200 A and above, where individual

load compensation cannot be achieved, overall

compensation at main or sub-main distribution levels

shall be provided by incorporating capacitor banks with

automatic regulated steps. For residential premises the

limitation shall be a 400 A feeder.

The PF correction capacitor shall be a dry,

encapsulated, sealed type conforming to IEC 61921.
Capacitors shall be enclosed or guarded to prevent

accidental contact of conducting metal parts with

exposed energized parts, terminals or buses associated

with them.

Capacitors installed for PF correction shall be provided

with the means for automatic, immediate discharge

when the capacitor is disconnected from the source of

supply.
The discharge circuit shall be either permanently

connected to the terminals of the capacitor or

capacitor bank, or provided with automatic means of

connecting it to the terminals of the capacitor bank

on removal of voltage from the line. Manual means of

switching or connecting the discharge circuit shall not

be provided.
The capacitors and associated components [such as

PF regulator, indicating instruments, contactors (of

capacitor switching duty), control switches, etc.] shall

be designed and rated for operation based on:
a) the electric supply;
b)

the ambient conditions specified in G.4.6;

c) the selection details recommended in G.4.13.
Capacitor units shall be designed for temperature class

D in accordance with IEC 61921.
The current-carrying capacity of conductors that

connect a capacitor to the terminals of a motor or to

motor circuit conductors shall be:
1) a minimum of one-third of the current-carrying

capacity of the motor circuit conductors; and

2) a minimum of 1.5 times the rated current of the

capacitor in all cases.

An overcurrent device shall be provided in each circuit

for each capacitor bank. A separate overcurrent device

is not required for a capacitor connected on the load

side of a motor overload protective device. The rating

or setting of the overcurrent device shall be as low as

practicable.

The capacitor banks installed for PF correction are

major contributors to potential resonance. Such

resonance conditions can magnify harmonic levels.

Parallel resonance gives rise to a high impedance

across the network and can cause voltage and current

amplification. Network studies shall be carried out to

determine the correct rating of capacitors and their

operation without causing resonance. Mitigation

measures shall be taken such as installing suitable

harmonic filters or reactors. The capacitors shall

be suitable for operation under harmonic current

conditions. To minimize this risk of harmonic currents,

harmonic filter reactors shall be provided in series with

capacitors. Tuning of the capacitors, harmonic filter

reactors shall be made below the lowest harmonic

order present in the network.
The contactors used in the capacitor banks shall be

able to withstand switching surge. Suitable means shall

be installed to isolate each capacitor, capacitor bank, or

capacitor installation from all sources of voltage and to

remove the unit from service.

Dubai Building Code

Part G: Incoming utilities

G 66

All non-current-carrying metal parts of capacitors shall

be earthed as specified in G.4.19.

Each capacitor shall be provided with a name plate

indicating the following information:
i)  rated voltage;
ii)   frequency;
iii)  kVAr;
iv)  number of phases;
v)  discharge device;
vi)   name of the manufacturer.
Wherever a capacitor bank/panel is installed on the

supply side of DEWA kWh metering, adequate sealing

provision shall be made as specified in G.4.5.

In premises where capacitor banks are not installed and

individual equipment is provided with suitable means

for PF correction, a PF meter shall be provided in the

MDB for displaying the PF. If PF deviates from the

requirement specified by the designer, consumers shall

arrange for PF correction equipment to maintain the

PF close to 0.95 lagging.

The capacitor bank panel shall be provided with a

suitably rated main incomer isolating switch. This shall

be a three-pole isolator or MCCB. The handle of the

incomer isolator or MCCB shall be interlocked with the

door to ensure that the capacitor bank is de-energized

when the door is open.

Capacitor banks shall be provided with forced

ventilation. They shall have double enclosures to

limit the temperature rise for outdoor/open to sky

area installations. A trip mechanism with alarm shall

be provided to operate in the event of failure of the

ventilation/excess temperature rise.

G.4.20.2 Harmonics and rapid voltage changes

A consumer’s load shall not cause deviations of the

voltage characteristics other than those permitted by

BS EN 50160 and IEC 61000.
The on-site measurements to determine compliance

with the harmonics limits and any excess deviations

shall be carried out by the consumer. The following

characteristics of a supply voltage shall be taken into

account:
a)  power frequency;
b)  magnitude of the supply voltage;
c)  supply voltage variations;
d)

rapid voltage changes and flickers;

e)  supply voltage dips;
f)  short interruptions of the supply voltage;
g)  long interruptions of the supply voltage;
h)  temporary power frequency over voltages;
i)  transient over voltages;
j)  supply voltage unbalance;
k)  harmonic voltage;
l)  inter-harmonic voltage;
m) mains signalling voltage.

G.4.20.3

Undervoltage (UV) relays with auto

reset timer

All air-conditioners and air-conditioning units/plants/

equipment installed within the consumer’s installation

shall be provided with UV relays that trip the circuit

breakers/contactors associated with these relays.
The tripping shall occur immediately and without any

intentional time delay if the supply voltage drops to or

below 75% of nominal and remains at or below 75%

for a duration of 0.2 s. Tripping shall not occur if the

supply voltage recovers above 75% within 0.2 s.

The UV relay’s auto-reset timer shall have an

adjustable time setting between 5 min and 10 min.

The circuit breakers/contactors associated with the

UV relay shall have an auto-closing facility to restore

supply to the chillers/air conditioning units, after

normalization of supply voltage, when the relay is

reset automatically. The auto-closing facility shall

have a motorized operation. The auto-reset timer of

the UV relays shall be set at values specified in the

manufacturer’s schedules, approved by DEWA, to suit

individual installation. Necessary provision for sealing

may be incorporated in the relay to restrict access for

adjustments of the setting.

Dubai Building Code

Part G: Incoming utilities

G 67

UV relays with auto-reset timers shall normally be

incorporated within the respective air-conditioning

unit/equipment or in their control panels. For normal

air-conditioners, UV relays with auto-reset timers may

be provided within the consumer’s DB for individual or

group of air-conditioning units. Prior approval shall be

obtained from DEWA for each application.
The UV relays shall only be applied to trip the

respective air-conditioning units/plant or equipment

sensitive to voltage variations. The UV relays shall not

be applied to trip LV incomer circuit-breakers/ACB

within the main LV panel. The UV relays with

associated controls shall be checked and maintained

regularly. The 75% voltage threshold and tripping time

of the air-conditioning units/plants/equipment shall be

confirmed to DEWA after installation.

G.4.21 Construction sites

G.4.21.1 General

Assemblies for the distribution of electricity on

construction sites shall conform to BS 4363 and BS

EN 61439.

Equipment shall be identified by a temporary label

identifying the supply location, and shall be compatible

with the particular supply from which it is energized.

It shall only contain components connected to a single

installation.

Cables shall not be installed across a site, road

or walkway unless the cable is protected against

mechanical damage.
All cables used on construction sites shall have a

metal sheath and/or armour, both of which shall be

effectively earthed and continuous.
Wiring systems shall be arranged such that no strain

is placed on the terminations of conductors, unless the

terminations are designed for this purpose.
Assemblies for construction sites shall incorporate

suitable devices for switching and isolating the

incoming supply.
A circuit breaker shall be provided for isolating the

incoming supply. The circuit breaker shall either be

suitable for securing in the off position by padlock, or

installed inside a lockable enclosure.
Safety and standby supplies shall be connected by

means of devices arranged to prevent interconnection

of the different supplies.
Metering cabinets, DBs and wiring installations

installed outdoors shall be weatherproof

(IP 65 in accordance with BS EN 60529).

G.4.21.2 Wiring systems and distribution boards

Cables which are not installed in conduit or trunking

shall be:
a) armoured;
b) protected against accidental or deliberate

interference by persons; and

c) protected against the weather.
A means of emergency switching shall be provided on

the supply to all equipment from which it might be

necessary to disconnect all live conductors in order to

remove a hazard.
Equipment shall be located, and notices displayed,

in such a way as to facilitate immediate emergency

disconnection of the electricity supply. Locking

arrangements shall be provided that can be removed

in an emergency (e.g. panic bar or keys available in a

break-out box).
Where a proposal for more than one feeder means

that MDBs are installed at different locations, the

emergency power out facility shall be provided at a

single location.

It might be necessary to use a reduced LV supply

for portable tools where there is a high exposure to

potential damage, or where persons are required to

operate such equipment in confined spaces or other

hazardous circumstances. A reduced LV shall be used

where deemed necessary.

Dubai Building Code

Part G: Incoming utilities

G 68

Temporary electrical systems for entertainment and

similar purposes shall be provided in accordance with

BS 7909.

G.4.21.3 Earth leakage protection

In addition to the overcurrent and short-circuit

protection, every circuit shall be protected for earth

leakage.
All of the following shall be protected with an

ELCB/RCCB of rated operating current 30 mA:

final sub-circuits connected to 13 A switched

socket outlets;

b) portable tools;
c) equipment.

A 100 mA ELCB/RCCB shall be provided for the

protection of other lighting circuits,

fixed equipment, etc. unless otherwise specified.

The consumer shall check and test the earthing

systems, operation of ELCBs/RCCBs, wiring

installation, etc. regularly to verify that the installation

is safe, and shall take remedial action if necessary.

Dubai Building Code

Part G: Incoming utilities

G 69

G.5 Electric vehicle (EV) charging points

G.5.1

Charging modes

G.5.1.1

General

IEC 61851 specifies four different modes of conductive charging for electric vehicles. The four modes are summarized in G.5.1.2 to G.5.1.5.

Figure G.31

Electric vehicle Mode 1 charging

Figure G.32

Electric vehicle Mode 2 charging

Key

01: Battery

02: EV inlet

03: Connector

04: On-board charger

05: Plug

06: Socket outlet

Key

01: Battery

02: EV inlet

03: Connector

04: On-board charger

05: Plug

06: Socket outlet

07: In-cable control box

G.5.1.2

Mode 1 charging

Mode 1 charging is illustrated in Figure G.31. Alternating current (AC) is delivered

to the on-board charger of the EV, via a standard socket outlet and a charging

cable without communication function. An RCD for shock protection is provided on

the supply side of the fixed electrical installation. Mode 1 is not suitable for longer

periods of charging at home or the work place.
Mode 1 is not permitted due to the lack of safety measures associated with this

mode of charging.

G.5.1.3

Mode 2 charging

Mode 2 charging is illustrated in Figure G.32. The charging cable assembly

incorporates an in-cable control box. The fixed electrical installation for the charging

facility is similar to that of Mode 1 except that the final circuit, protective device and

socket shall be of a suitable rating for the connected load, and shall not exceed 32 A,

in order to cater for the higher level of charging current.

Dubai Building Code

Part G: Incoming utilities

G 70

G.5.1.4

Mode 3 charging

Mode 3 charging is illustrated in Figure G.33. It employs dedicated EV service

equipment (EVSE) and a charging cable assembly. The control pilot cable of the

charging cable assembly allows communication between the EVSE and the on-board

charger. Communication functions include:
a)

verification of connection with the EV;

b)  continuous checking of protective earth conductor integrity;
c)  energization and de-energization of the supply;
d)  selection of the charging rate.

Figure G.33

Electric vehicle Mode 3 charging

Figure G.34

Electric vehicle Mode 4 charging

Key

01: Battery

02: EV inlet

03: Connector

04: On-board charger

05: Plug

06: Socket outlet

07: AC charger facility

Key

01: Battery

02: EV inlet

03: Connector

04: DC quick charging facility

G.5.1.5

Mode 4 charging

Mode 4 charging is illustrated in Figure G.34. It employs an off-board charger to

deliver direct current to the battery, bypassing the on-board charger. This mode

can charge an EV in a relatively short time because a higher electrical power is used

(ranging from 20 kW to 120 kW).

NOTE: Maximum charging capacity of a DEWA charger shall be limited to 25kW or

below per charging outlet, subject to available load capacity.

Dubai Building Code

Part G: Incoming utilities

G 71

G.5.2

EVSE design requirements

For the permitted charging modes described in G.5.1.3

to G.5.1.5, the following requirements shall be met.
a) The following general requirements shall be met.

1) Installation of a private charging outlet shall be

subject to prior DEWA approval.

2) The design of EVSE shall enable maintenance

and service work to be carried out safely.

EVSE shall be installed with sufficient space

around it, in accordance with the manufacturer’s

instructions, to allow for ventilation and cooling

of the equipment.

4) EVSE shall be installed in such a way as to

minimize the distance between the EV inlet and

the charging equipment.

5) EVSE shall not be installed in locations where

a potentially explosive atmosphere exists, such

as petrol stations. Where such locations require

EVSE, it shall be installed outside the hazardous

zone.

b) The following requirements shall be met for circuits.

1) EVSE shall be supplied by a separate and a

dedicated radial circuit. The radial circuit shall

supply no other loads, except for ventilation

equipment required by the EVSE.

NOTE: More than one EVSE can be fed from the

same supply circuit, provided that the combined

current demand of the equipment does not

exceed the rating of the supply circuit.

2) Cables supplying EVSE shall be mechanically

protected by means of metal sheath/armour, or

installed inside a conduit made from either:
i) rigid steel;
ii) plastic; or
iii) PVC.

Each final circuit shall be sized to carry the rated

current of the EVSE, with limited voltage drop

as required.

Where the final circuit supplies more than one

EVSE, there shall be no diversity. A diversity

factor (usually greater than one) may be used

for a dedicated distribution circuit supplying

multiple EVSE charging points, provided that

load control is available.

c) The following requirements shall be met for sockets

and connectors.
1) One socket outlet and/or vehicle connector shall

be used to charge one EV.

2) EVSE shall be installed such that the main

operating controls and any socket outlet are

between 0.75 m and 1.2 m above ground.

3) The EV manufacturer’s instructions shall be

followed when determining the type of socket

outlet to be installed.

d) The following requirements shall be met for

isolation and switching.
1) A means of isolating the supply to the EVSE

circuit shall be provided, in accordance with

G.4.13.2. The isolating device shall be:
i) capable of being locked in the open position;
ii) located in a position that is readily accessible

for maintenance purposes; and

iii)

suitably identified by marking and/or

identification.

2) Where an emergency switch is provided, it shall:

i) be located in a position that is readily

accessible, in accordance with the

manufacturer’s recommendations;

ii)

be suitably identified by marking and/or

labelling; and

iii) disconnect all live conductors, including the

neutral.

e) The following requirements shall be met for

protection.
1) EVSE and all associated equipment shall

be selected and erected in such a way as to

minimize the risk of overloads and short-

circuits.

Each final circuit shall be individually protected

against fault current by a suitably rated

overcurrent protective device.

Dubai Building Code

Part G: Incoming utilities

G 72

3) Basic protection against electrical shock shall be

provided by automatic disconnection of supply

or electrical separation (see G.4.13.2).

4) Every charging point shall be individually

protected by a 30 mA RCD. The RCD shall

disconnect all live conductors, including the

neutral.

The requirements of G.4.19 shall be met on final

circuits.

f) The following requirements shall be met for

labelling.
1)

The labelling and identification requirements

listed in G.4.18.6 shall be met, together with the

following.

2) All labels on EVSE shall be:

i) clear;
ii) easily visible;
iii) written in both Arabic and English; and
iv)

constructed and affixed to remain legible for

as long as the enclosure is in use.

3) An operation instruction for the charging facility

shall be displayed at a prominent location at all

parking spaces with EVSE. The instruction shall

include the following information:
i) rated voltage (V);
ii)

frequency (Hz);

iii) current (A); and
iv) number of phases.

4) Directional signage inside and outside car parks

is recommended to direct EV drivers to parking

spaces with EVSE.

Dubai Building Code

Part G: Incoming utilities

G 73

G.6 Renewable energy

G.6.1

General

As a type of renewable energy, solar energy is clean

and secure. DEWA encourages the use of solar energy

to reduce reliance on traditional energy sources

(such as gas, oil and coal), which are diminishing.
The onsite generation of electricity from a solar PV

shall be by a solar grid-connected system. The grid-

connected solar generator shall be connected to the

DEWA network, and operated and maintained in

accordance with applicable legislation

[Ref. G.4]

and

DEWA Shams Dubai regulations

[Ref. G.5]

. System

documentation requirements are described in G.6.2.

NOTE 1: The connection of a solar PV system or

distributed renewable resource generation (DRRG) to

the DEWA grid is subject to DEWA approval.
NOTE 2: Detailed technical requirements are set out in

DEWA Technical publications and resources

[Ref. G.6]

The designer shall comply with DEWA specifications,

acceptable standards, procedures and other

requirements published on DEWA website

(Shams Dubai section). The requirements are updated

regularly and form an integral part of the DBC.
Solar power generation systems shall conform to

Section 2, Ch. 14 of the UAE FLSC

[Ref. G.1]

and

this section.

Building attached photovoltaics (BAPV) systems

attached to roofs, excluding curved or special roofs,

are permitted to achieve a minimum fire classification

of Class C when tested as per the test standards in

Section 2.2.4, Ch. 14 of the UAE FLSC

[Ref. G.1]

The minimum fire classification permitted for building

integrated photovoltaics (BIPV) and BAPV systems

other than the above shall be confirmed with DEWA

and DCD upon commencement of design.

G.6.2

System documentation requirements

Consultants and Contractors registered with DEWA

for activities related to grid-connected solar PV

systems (DRRG Solar PV Consultants and DRRG

Solar PV Contractors) shall follow the DEWA

guidelines published on the DEWA website for these

requirements. Applications for solar connections shall

be submitted online and shall include the following

documents:
a)  basic system information;
b)  details of the system designer;
c)  details of the system installer, operation and

maintenance procedure.

NOTE: Detailed requirements are set out in DEWA

Connection guidelines for distributed renewable

resources generators connected to the distribution

network

[Ref. G.7]

G.6.3

Wiring diagram datasheets

An annotated/table form single line wiring diagram

that meets the requirements of DEWA Shams Dubai

regulations

[Ref. G.5]

shall be uploaded with the

DEWA application. It shall include the following

information:
a)

PV array general specifications:

1)  PV module type(s);
2)  total number of PV modules;
3)  number of PV strings;
4)  PV modules per string;

b) PV string information:

string cable specifications – size and type;

string fuse specifications (where fitted) – type

and voltage/current ratings;

c) PV array electrical details:

PV array main cable specifications, AC and

DC – size and type;

2) PV array junction box locations (where

applicable);

3) DC isolator type, location and rating

(voltage/current);

d) earthing and overvoltage protection:

details of all earth/bonding conductors – size

and connection points (to include details of PV

array frame equipotential bonding cable where

fitted);

Dubai Building Code

Part G: Incoming utilities

G 74

Design verification and details of any

connections to an existing lightning protection

system or supplementary lightning protection

system that is to be provided;

3) details of any surge protection device installed

(on both AC and DC lines), including location,

type and rating;

e) AC electrical details, inbuilt and external

protections:
1) AC isolator location, type and rating;
2) AC overcurrent protective device location, type

and rating;

3) residual current device location, type and rating.

G.6.4

Labelling and identification

A solar PV installation shall meet the requirements of

DEWA Shams Dubai regulations

[Ref. G.5]

, together

with the following requirements.
a) All circuits, protective devices, switches and

terminals shall be labelled to identify all relevant

parts of the installation.

b) All DC junction boxes (PV generator and PV

array boxes) shall be provided with caution labels

indicating the risk due to dual source.

c) The main AC isolating switch shall be clearly

labelled.

d) A single line wiring diagram shall be displayed

within the respective electrical rooms/panels.

e) Inverter protection settings and installation details,

as applicable, shall be displayed.

f) The procedures for emergency shutdown shall be

displayed.

All signs and labels shall be suitably affixed.

h) Durable copies of all test and commissioning data

shall be provided to the consumer.

G.6.5

Metering and metering provision

DEWA requires access to meter cabinets for the

installation of smart meters (PV generation check

meters and tariff meters). Contractors shall install

meter cabinets in an easily accessible location, in

accordance with G.4.5.

Dubai Building Code

Part G: Incoming utilities

G 75

G.7 Substation and MV installations

G.7.1

MV network design requirements

and guidelines (11 kV)

G.7.1.1

General

G.7 outlines the design requirements where:
a) a DEWA substation is required within the building

or plot boundary; and

b) an 11kV medium voltage (MV) network provides

the primary power to the building or plot.

G.7.1.2

Reliability of supply

A ring supply consisting of two feeders (a two-feed

ring) is the normal feeding arrangement for power

supply. A three-feed ring arrangement may be adopted

for cases where all MV switchgears/RMUs are installed

in one location to ensure specific supply reliability.
For reliable power supply, N-1 line criterion may be

used in some installations. In case of power failure

in one feeder, the other feeder should be capable of

meeting the entire demand for a maximum of 6 h.

G.7.1.3

Standard cable sizes

The DEWA standard 11 kV cable sizes are:
a) 3/C 300 mm

copper XLPE;

b) 3/C 240 mm

copper XLPE;

c) 3/C 240 mm

aluminium XLPE.

G.7.1.4

Cable loads

The maximum sustained loads of 11 kV feeder are:
a) for 300 mm

copper XLPE cables (summer rating):

175 A/3 MW;

b) for 240 mm

copper XLPE cables (summer rating):

160 A/2.7 MW.

The single unit load demand shall not exceed the

maximum sustained current of 175 A/3 MW for an

11 kV feeder cable.
All 11 kV private switchgear shall have a rated

symmetrical short-circuit current not less than 31.5kA,

with a short time current rating of 3 s.

For private equipment with bulk loads (e.g. furnaces or

district cooling) requiring direct MV supply, space for

metering units at the customer’s premises/substation

shall be provided. Necessary documents, drawings and

SLDs shall be submitted for comments/approval at

design stage.

G.7.1.5

Parallel operation

Parallel operation of DEWA’s MV feeders are not

allowed in any circumstances. Electrical and mechanical

interlocking shall be provided where required.
Standby generators are not allowed to operate in

parallel with DEWA’s network. Interlocking shall be

provided where required.

The customer shall maintain a PF between 0.95

(lagging) and unity at the point of connection with

DEWA’s MV Network.
The customer shall comply with DEWA’s limits of

maximum allowable motor starting currents, and

corresponding electrical power ratings, as indicated in

Table G.22.

Motor electrical power rating

Max. starting current*

Less than or equal to 600 kW

6 × full load current

Above 600 kW and up to 1,200

4 × full load current

Above 1,200 kW and up to

1,800 kW

3 × full load current

Above 1,800 kW and up to

2,400 kW

2 × full load current

Above 2,400 kW and up to

3,000 kW

1.5 × full load current

Motor electrical power rating

Max. starting current*

* Maximum current per feeder during motor starting (including

other running motors and loads) should not exceed 350 A at any

circumstances.

Table G.22 DEWA limits of maximum allowable motor starting currents

Dubai Building Code

Part G: Incoming utilities

G 76

The following information shall be submitted for

approval at design stage:
a)

motor specification;

starting method characteristics and specifications;

c) number of motor starts per day and operation

sequence;

SLDs and equipment layouts.

G.7.1.6

Harmonics

For loads that inject harmonics currents into DEWA’s

network, harmonic (voltage and current) study at the

point of connection is required. The study shall be

submitted for DEWA approval at the design stage.
The customer shall comply with DEWA’s limits of

harmonic emissions for voltage and current, based on

IEC 61000-3-6:2.0-2008. Detailed specifications and

size of equipment, including harmonics spectrum, shall

be provided for DEWA approval.
After commissioning of the project, harmonics and

flicker site measurements shall be conducted. A report

of the measurements shall be submitted to DEWA.

Where the measured values exceed DEWA’s limits, the

customer shall arrange for a solution to reduce the

harmonic emissions to the permissible limits.

G.7.1.7

Cable trenches

The maximum allowable number of cables per trench

for 11 kV cables is 20. These cables shall be arranged

in a maximum of two layers within a trench with a

maximum width of not more than 3 m on both sides

of the road, close to 132/11 kV substation.
A minimum of 2 m clearance shall be maintained

between any MV cable trench and the surrounding

heat sources such as 132 kV cable trench.
The permitted horizontal spacing between MV cables

is 150 mm (edge to edge for MV cables) and permitted

vertical spacing between layers is 100 mm (edge to

edge for 11 kV cables). Refer to Figure G.35.

Figure G.35

Typical minimum clearance between cables installed within trench

Crossing between 132 kV cables and MV cables

shall not be used unless it is unavoidable. A separate

corridor shall be allocated within the premises for MV

cable laying along the road.

In soil with a resistivity below 1.6 °C-m/W, the backfill

around MV cables shall have a maximum moisture

content of 2% and be at 90% compaction.
An SLD illustrating the protection schemes shall be

submitted with a relay setting calculation at the design

stage.

Dubai Building Code

Part G: Incoming utilities

G 77

G.7.2

Substation construction within private plots

G.7.2.1

General

Building-type substations shall be constructed for

projects such as labour accommodation, schools,

nurseries and hospitals.
Pocket (self-contained) substations shall not be

installed at petrol stations and inside buildings.
Expansion joints shall not be used in RMU rooms or

transformer rooms, or on ceilings.

G.7.2.2

Substation location

The substation shall be positioned in a dedicated room

or housing.
Substations located in basement levels shall have

transformer rooms in the first basement level only.
LV electrical rooms shall be adjacent to the substation

room if the main panel is private.
Wet areas shall not be installed above substations

(see G.7.4).

G.7.2.3

Substation parameters

A single room substation at ground floor (see G.7.5.1)

shall have a clear height of not less than 3,700 mm.

For split/basement substation arrangements (see

G.7.5.2), the RMU room at ground floor shall have a

clear height of not less than 3 m.
A basement transformer room shall have a clear height

of not less than 3 m.

The substation finished floor level (FFL) shall be

maintained between 150 mm and 300 mm above

the adjacent ground level (towards the door side).

Additional room parameters are shown in Figure G.36

and Figure G.37.
The FFL of a transformer room at basement level shall

be maintained between 75 mm and 150 mm higher

than the adjacent outside ground level (towards door

side).

Dubai Building Code

Part G: Incoming utilities

G 78

Figure G.36

General dimensional details of substations within buildings (m)

Key

01: 150 mm øPVC at trench level

02: Transformer base

03: RMU

04: RTU

05: All louver windows as door details above FFL of

0.6 m x 3 m (w) x 2.15 m (h)

06: 600 mm opening at channel base level

2.75

2.15

0.60

3.70

5.00

3.00

0.60

0.45

0.95

0.15

0.63

0.20
0.40

0.85

0.45

3.0

1.0

1.68

3.05

6.54

5.00

0.92

0.60

0.77

0.60

2.05

0.90

0.40

1.00

1.03

0.87

0.40

07: Door

08: Air intake louver

09: Chequered plate with two lifting holes

10: 25 mm diameter lifting hole

11: Chequered plate cover

Dubai Building Code

Part G: Incoming utilities

G 79

0.40

0.30

0.15

0.65

0.30

0.15

0.95

0.50

1.00

0.30

0.15

0.65

0.30

0.15

0.95

0.20
0.40

0.85

0.45

0.92

0.60

0.77

0.90

0.40

1.00

1.03

0.40

0.50

1.00

0.20
0.40

0.85

0.45

0.92

0.60

0.77

0.90

0.40

1.00

1.03

0.40

Key

01: 150 mm øPVC at trench level

02: Transformer base

03: RMU

04: 13 mm × 6 mm flat bar welded to angle

05: 6 mm thick hot dip galvanized chequered

plate cover

06: 25 mm × 25 mm × 3 mm angle welded to

chequered plate cover on two side

07: 60 mm × 60 mm × 6 mm edge angle

08: T10 anchor welded to angle at 300 mm

centre-to-centre

09: Wall

10: Opening

11: Pre-cast concrete

12: Slope

13: Channel

14: Chequered plate

Dubai Building Code

Part G: Incoming utilities

G 80

G.7.2.4

Earthing

Substation earthing, which forms part of the

consumer’s scope, shall meet DEWA requirements at

design stage.
The following requirements shall be met for substation

neutral earthing schemes (see Figure G.38):

a) Two or more dedicated and interconnected earth

pits shall be provided for transformer earthing

and shall be connected to the substation earth

strips in a loop. The effective earth resistance value

measured from any neutral earthing strip shall be

less than 2.0 Ω.

b) Two or more dedicated and interconnected earth

pits shall be provided for transformer equipment

body earthing and shall be connected to the

transformer equipment body earth strips in a loop.

The effective earth resistance value measured from

any of the equipment body earth strips shall be less

than 2.0 Ω.

c) Interconnection of transformer neutral earthing

and equipment body earthing is not permitted.

d) Earth strips shall be mounted on the cable

trench wall at the nearest point to the respective

equipment, with a minimum clearance of 50 mm

from the wall.

e) Earth strips shall be provided with a minimum of

four 12 mm diameter holes for earth looping.

f) Earth conductors shall be copper material with

a minimum of 95 mm

diameter. If the length of

conductors exceeds 50 m, 120 mm

diameter

copper earth conductors shall be used.

g) In substations with multiple transformer and RMU

arrangements, the neutral earthing scheme outlined

shall be repeated for every two transformers and

the same equipment body earthing scheme to be

repeated for every three transformers and their

corresponding RMUs.

Key

01: Substation neutral

earth strips

02: Body neutral earth

strips

03: To neutral earth pits

04: To body earth pits

05: Substation room

Dubai Building Code (2021) - page 17