Abu Dhabi electrical exam practice (DoE, ADDC, AADC)
Electrical work in Abu Dhabi and Al Ain follows the Electricity Wiring Regulations, now issued by the Department of Energy (earlier editions by the Regulation and Supervision Bureau), with ADDC and AADC as the distribution companies.
The EWR is closely aligned with BS 7671 and IEC 60364, so questions mix regulation-specific values, such as the 10 Ω maximum earth resistance at the Main Earth Terminal of a TT system, with general design and testing principles.
What the questions cover
Cables & voltage drop, Calculations, Earthing & bonding, Fire, life safety & ELV, Protection & RCDs, Regulations & procedures, Renewables & EV, Safety & isolation, Special locations, Supply & earthing, Switchgear & PFC, Testing & inspection.
Main references: The Electricity Wiring Regulations, DoE 2020 (earlier RSB editions 2007, 2014).
Key values to know
- EWR 2020 issued by the Department of Energy (earlier RSB editions 2007, 2014)
- TT: earth resistance at owner's MET ≤ 10 Ω
- LV < 1000 V a.c. between phases or < 600 V phase to earth
- HV > LV and < 36 kV between phases
- RLV ≤ 55 V to earth, 110 V between phases
- Foundation earth electrodes to BS 7430, with continuity and monitoring provision
- Consistent with BS 7671 and IEC 60364
- TN final circuits ≤ 32 A: 0.4 s; TT: 0.2 s (Table 41.1)
- Distribution circuits: TN 5 s, TT 1 s
- TT: RA × IΔn ≤ 50 V
- RCD: ≤ 300 ms at 1 × IΔn, ≤ 40 ms at 5 × IΔn
- Insulation: 500 V d.c. ≥ 1 MΩ; SELV/PELV 250 V d.c. ≥ 0.5 MΩ
- Max Zs = 230 × 0.95 / Ia (B: 5 In, C: 10 In, D: 20 In)
- CPC (Table 54.7): ≤16 → same; 16-35 → 16; >35 → half
- Main bonding ≥ 6 mm² Cu; supplementary 4 mm² (2.5 mm² protected)
- Buried earthing conductor, no corrosion protection: 25 mm² Cu
- Adiabatic S = √(I²t) / k
Sample questions with answers
1. Which body currently issues the Electricity Wiring Regulations for the Emirate of Abu Dhabi?
- DEWA
- Department of Energy (DoE)
- SEWA
- Ministry of Energy and Infrastructure
Show the answer
Answer: B - Department of Energy (DoE)
The EWR were first issued by the Regulation and Supervision Bureau (2007, revised 2009, 3rd edition 2014). The current 2020 edition is issued by the Department of Energy, which took over the regulator role.
Reference: EWR 2020, foreword
2. In the Abu Dhabi EWR, Low Voltage is defined as an a.c. voltage:
- Below 400 V between phases
- Below 1000 V between phases, or below 600 V between any phase and earth
- Below 1500 V between phases
- Below 11 kV between phases
Show the answer
Answer: B - Below 1000 V between phases, or below 600 V between any phase and earth
LV is below 1000 V a.c. between phases or below 600 V a.c. phase to earth (d.c.: below 1500 V between conductors or 900 V to earth).
Reference: EWR, cl. 2.1 definitions
3. The technical principles of the Abu Dhabi Electricity Wiring Regulations are consistent with:
- NFPA 70 (NEC)
- BS 7671 and IEC 60364
- AS/NZS 3000 only
- IEEE 80 only
Show the answer
Answer: B - BS 7671 and IEC 60364
The EWR state that they are consistent with BS 7671 (IET Wiring Regulations) and IEC 60364. That is why most common questions in the Abu Dhabi exam also follow BS 7671 logic.
Reference: EWR, cl. 3.1
4. Which conditions apply when foundations or piles are used as an earth electrode under the Abu Dhabi EWR?
- Electrical continuity between all metalwork forming the electrode
- Provision for measuring and monitoring earth resistance at regular intervals
- No testing is needed because foundations are always low resistance
- The reinforcement must be aluminium
Show the answer
Answer: A, B - Electrical continuity between all metalwork forming the electrode; Provision for measuring and monitoring earth resistance at regular intervals
The EWR requires proven continuity of the metalwork, provision for regular measurement and monitoring, and consideration of corrosion and DC leakage. Foundations are never exempt from testing.
Reference: EWR 2020, cl. 6.4.8
5. The Abu Dhabi EWR defines High Voltage (internationally called Medium Voltage) as an a.c. voltage greater than LV and less than:
- 11 kV between phases
- 22 kV between phases
- 36 kV between phases
- 132 kV between phases
Show the answer
Answer: C - 36 kV between phases
HV in the EWR is above LV and below 36 kV between phases, or 21 kV phase to earth. The typical Abu Dhabi distribution voltages 11 kV and 33 kV both fall in this band.
Reference: EWR, cl. 2.1 definitions
6. For a TT system, what is the maximum disconnection time for a final circuit rated not exceeding 32 A at 230 V?
- 0.1 s
- 0.2 s
- 0.4 s
- 5 s
Show the answer
Answer: B - 0.2 s
Table 41.1 of BS 7671 gives 0.2 s for TT final circuits ≤32 A at 230 V (0.4 s for TN). This short time is usually met by an RCD rather than an overcurrent device.
Reference: BS 7671 Table 41.1
7. Which steps form part of a safe isolation procedure?
- Lock off the isolator and fit a caution tag
- Prove the voltage indicator on a proving unit before and after testing
- Test between all conductor combinations, including line to earth
- Rely on the switch position indicator to confirm it is dead
Show the answer
Answer: A, B, C - Lock off the isolator and fit a caution tag; Prove the voltage indicator on a proving unit before and after testing; Test between all conductor combinations, including line to earth
Isolate, lock off and tag, prove the tester, test all combinations, then prove the tester again. The switch position alone never proves a circuit is dead; contacts can weld or the wrong circuit may be isolated.
Reference: GS38; BS 7671 537
8. What minimum illuminance does BS EN 1838 require for open area (anti-panic) emergency lighting?
- 0.2 lux
- 0.5 lux
- 1 lux
- 5 lux
Show the answer
Answer: B - 0.5 lux
Open area (anti-panic) lighting needs 0.5 lux minimum across the core area, excluding a 0.5 m border.
Reference: BS EN 1838
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These questions are written from the published regulations and standards and are not copied from any real exam. Authorities and boards do not publish their question banks, and pass marks and formats can change, so confirm the current details with the body concerned.