100+ Free DEWA Electrical Exam Practice Questions

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Sample DEWA Electrical Exam Practice Questions

Try these sample questions to test your DEWA Electrical Exam exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1What is the nominal low-voltage supply declared by DEWA for consumer electrical installations in Dubai?

A.240/415 V, 60 Hz, 3-phase, 4-wire

B.230/400 V ± 10%, 50 Hz, 3-phase, 4-wire

C.220/380 V, 50 Hz, 3-phase, 3-wire

D.120/208 V, 60 Hz, single-phase

Explanation: The DEWA Regulations for Electrical Installations declare a nominal supply of 230/400 V ± 10%, 50 Hz, in a 3-phase, 4-wire arrangement with a separate neutral and protective conductor, in line with IEC 60038. All consumer equipment must be rated for these conditions.

2Under the DEWA system, where is the neutral conductor solidly earthed?

A.At every consumer distribution board

B.At DEWA's substation only

C.At the main earth electrode of each villa

D.It is never earthed

Explanation: In the DEWA TN-S type arrangement the neutral is solidly earthed at DEWA's substation and must NOT be re-earthed within the consumer's installation. Connecting neutral to earth downstream would create dangerous parallel return paths and defeat earth-fault protection.

3What residual operating current must an RCD have to provide 'additional protection' against electric shock per DEWA/BS 7671?

A.100 mA

B.300 mA

C.30 mA

D.500 mA

Explanation: Additional protection against electric shock is provided by a 30 mA RCD. A residual current of 30 mA or less is required so the device disconnects before a shock current becomes lethal, protecting against direct contact when other measures fail.

4Per DEWA regulations, socket-outlets of which rating must generally be protected by a 30 mA RCD?

A.Only outdoor sockets

B.All socket-outlets rated 20 A or less, unless specifically exempt

C.Only sockets above 32 A

D.Three-phase sockets only

Explanation: DEWA requires 30 mA RCD additional protection for all socket-outlets rated 20 A or less unless an exemption applies. This mirrors BS 7671 and protects users of portable appliances plugged into general-purpose sockets.

5Cables concealed in a wall at a depth of less than 50 mm must be provided with which additional protection?

A.A 30 mA RCD

B.Double insulation only

C.A 100 mA time-delayed RCD

D.An isolating transformer

Explanation: Cables buried in walls at a depth of less than 50 mm without earthed mechanical protection must be protected by a 30 mA RCD. This guards against the risk of a nail or screw penetrating the cable and making accessible metalwork live.

6In BS 7671, what is the maximum disconnection time for a 230 V final circuit not exceeding 63 A on a TN system?

A.5 seconds

B.0.4 seconds

C.1 second

D.0.2 seconds

Explanation: For TN-system final circuits up to 63 A at the 120-230 V band, the maximum disconnection time is 0.4 seconds (BS 7671 Table 41.1). The short time limits how long exposed-conductive-parts can remain live under an earth fault.

7Which IEC/BS conductor colour identifies the protective earth (PE) conductor?

A.Blue

B.Brown

C.Green-and-yellow

D.Black

Explanation: Under the IEC harmonised colours adopted in DEWA installations, the protective earth conductor is green-and-yellow. This bicolour is reserved exclusively for earthing and must never be used for live or neutral conductors.

8In the IEC harmonised colour code, which colour is used for the neutral conductor?

A.Brown

B.Blue

C.Grey

D.Green-and-yellow

Explanation: The neutral conductor is blue in the IEC harmonised colour code used in Dubai installations. Brown, black and grey are reserved for the three line conductors, and green-and-yellow for earth.

9What is the maximum permitted voltage drop for a lighting circuit measured from the origin of the installation?

A.5% of nominal voltage

B.3% of nominal voltage

C.8% of nominal voltage

D.1% of nominal voltage

Explanation: BS 7671 limits voltage drop to 3% of nominal voltage for lighting circuits (about 6.9 V on a 230 V supply). Excessive drop dims luminaires and can shorten lamp life, so this is checked at the design stage.

10What is the maximum permitted voltage drop for power (non-lighting) circuits under BS 7671?

A.3%

B.5%

C.10%

D.2%

Explanation: For circuits other than lighting (sockets, fixed appliances, motors) BS 7671 permits a maximum voltage drop of 5% of nominal voltage, about 11.5 V on a 230 V supply. Keeping within this ensures equipment receives adequate voltage to operate correctly.

About the DEWA Electrical Exam Exam

The DEWA electrical contractor competency exam is the assessment a person must pass to perform electrical contracting and installation work connected to the DEWA network in Dubai. It is a short multiple-choice test of about 30 questions in one hour, requiring 70% to pass, covering the DEWA Regulations for Electrical Installations, BS 7671 wiring principles, earthing and protection, cable sizing and substation requirements.

Assessment

Short multiple-choice competency test of approximately 30 questions, based on the DEWA Regulations for Electrical Installations together with BS 7671 (IET Wiring Regulations), IEC standards and basic electrical theory.

Time Limit

Approximately 1 hour (60 minutes)

Passing Score

70% is required to pass, which is roughly 21 correct answers out of about 30 questions. An immediate re-sit is generally allowed if you do not pass.

Exam Fee

Approximately AED 410 per attempt, set by DEWA/Dubai Municipality and subject to periodic change. Confirm the current fee on the official DEWA portal. (Dubai Electricity and Water Authority (DEWA) / Dubai Municipality)

DEWA Electrical Exam Exam Content Outline

20%

DEWA Regulations and Approval Procedures

DEWA supply characteristics, approved-contractor requirements, drawing approval, labelling, certification and inspection items.

25%

Earthing, Bonding and Protection

TN-S earthing, main and protective bonding, 30 mA RCD/ELCB additional protection, disconnection times, circuit breakers, fuses and discrimination.

20%

Cable Sizing and Load Calculation

Current-carrying capacity, derating for ambient temperature, grouping and insulation, voltage drop limits, diversity and device co-ordination.

15%

BS 7671 Wiring and Installation Practice

IEC conductor colours, IP ratings, concealed cables, bathroom zones, insulation-resistance/polarity/continuity testing and fire safety.

12%

Substation and Transformer Requirements

Switch and transformer room location and ventilation, RMUs, transformers, fault levels, access, earth electrodes and step-and-touch potentials.

Electrical Theory and Safety

Ohm's law, single- and three-phase power and voltage relationships, power factor, safe isolation and general electrical safety.

How to Pass the DEWA Electrical Exam Exam

What You Need to Know

Passing score: 70% is required to pass, which is roughly 21 correct answers out of about 30 questions. An immediate re-sit is generally allowed if you do not pass.
Assessment: Short multiple-choice competency test of approximately 30 questions, based on the DEWA Regulations for Electrical Installations together with BS 7671 (IET Wiring Regulations), IEC standards and basic electrical theory.
Time limit: Approximately 1 hour (60 minutes)
Exam fee: Approximately AED 410 per attempt, set by DEWA/Dubai Municipality and subject to periodic change. Confirm the current fee on the official DEWA portal.

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

DEWA Electrical Exam Study Tips from Top Performers

1Study the DEWA Regulations for Electrical Installations alongside BS 7671 fundamentals, since the exam blends DEWA-specific rules (supply voltage, switch-room location, approvals) with wiring-regulation theory.

2Memorise key numeric facts such as the 230/400 V 50 Hz supply, 30 mA RCD additional-protection rule, 0.4 s and 5 s disconnection times, and the 3% lighting / 5% power voltage-drop limits.

3Practise cable-sizing and load-calculation questions, including derating for Dubai's high ambient temperature, grouping and diversity, as these are common stumbling blocks.

Frequently Asked Questions

Who must pass the DEWA electrical contractor competency exam?

Anyone responsible for performing electrical contracting and installation work connected to the DEWA network in Dubai must demonstrate competency through this exam, which is administered under Dubai Electricity and Water Authority (DEWA) and Dubai Municipality requirements.

How many questions are on the DEWA electrical exam and how long is it?

The exam is short, with approximately 30 multiple-choice questions to be completed in about one hour. Always confirm the exact format with DEWA, as details can change.

What is the pass mark for the DEWA electrical exam?

You need 70% to pass, which is roughly 21 correct out of about 30 questions. If you do not pass, an immediate re-sit is generally permitted.

What does the DEWA electrical exam cover?

It is based on the DEWA Regulations for Electrical Installations together with BS 7671 (IET Wiring Regulations), IEC standards and basic electrical theory, including earthing and bonding, RCD protection, cable sizing and load calculation, installation practice and substation/transformer requirements.