Free EMA Electrician Licence Written Assessment Practice Questions

Sample Practice Questions

Try these 10 sample questions from the EMA Electrician Licence Written Assessment practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1A domestic circuit supplies appliances through several socket outlets. Under regulation 2 of the Electricity (Electrical Installations) Regulations, which term describes this circuit?

   1. A.Distribution circuit
   2. B.Final circuitCorrect answer: B
   3. C.Control circuit
   4. D.Auxiliary circuit

   Explanation: Regulation 2 defines a final circuit as "a circuit connected either directly to a device which utilises electricity, or indirectly to such a device by means of one or more socket outlets or other outlet points". The appliance circuit meets the indirect socket-outlet branch of that definition.

   Reference: Electricity (Electrical Installations) Regulations — reg. 2, definition of final circuit

2. 2A domestic single-line diagram needs a device designation that expressly identifies protection by residual-current detection. Which name specifically denotes that function?

   1. A.Miniature circuit breaker
   2. B.Moulded-case circuit breaker
   3. C.Residual current circuit breakerCorrect answer: C
   4. D.Thermal overload relay unit

   Explanation: The source states "The current balance in the conductors passing through the magnetic core therefore no longer exists, and the difference gives rise to a magnetic flux in the core.". An RCCB uses the residual-current principle. Overcurrent circuit breakers and thermal overload relays respond to different quantities unless additional residual-current functionality is specified. This asks what the designation expressly identifies, rather than whether an overcurrent breaker could have added residual-current accessories.

   Reference: Schneider Electric Electrical Installation Guide — Description of RCDs — Operating principle

3. 3An electrician must state the voltage of an AC circuit using the meaning assigned by the Electricity (Electrical Workers) Regulations. Which characteristic of the waveform is the statutory AC voltage?

   1. A.The arithmetic mean over a complete cycle
   2. B.The maximum instantaneous peak value
   3. C.The difference between waveform extremes
   4. D.The root mean square over a complete cycleCorrect answer: D

   Explanation: Regulation 2 specifies "in the case of alternating current, the virtual voltage or root mean square value (or the square root of the mean or average value of the squares of the instantaneous values) of the voltage during the complete cycle." Thus RMS, rather than mean, peak or peak-to-peak voltage, is required.

   Reference: Electricity (Electrical Workers) Regulations — reg. 2, definition of voltage, paragraph (b)

4. 4On a switchboard drawing, an MCB is specified with a thermal-magnetic trip unit. Which part responds to a sustained overload?

   1. A.The thermally operated bimetal stripCorrect answer: A
   2. B.The electromagnetic striker pin
   3. C.The manual operating handle
   4. D.The mechanical contact linkage

   Explanation: The source states "a thermally-operated bi-metal strip detects an overload condition, while an electromagnetic striker pin operates at current levels reached in short-circuit conditions". The thermal element responds to overload heating; the magnetic striker responds to short-circuit-level current. The handle and linkage operate the mechanism but do not provide overload sensing.

   Reference: Schneider Electric Electrical Installation Guide — Circuit-breaker construction — Description, trip-mechanism actuating device

5. 5When classifying a proposed installation under the Electricity (Electrical Installations) Regulations, what are the respective maximum AC and DC voltages within the definition of extra-low voltage?

   1. A.50 V AC and 120 V DCCorrect answer: A
   2. B.50 V AC and 50 V DC
   3. C.120 V AC and 120 V DC
   4. D.120 V AC and 50 V DC

   Explanation: Regulation 2 states "a voltage not exceeding 50V a.c. or 120V d.c., whether between conductors or between conductor and Earth". These are inclusive upper limits; the other pairs interchange the AC and DC thresholds or use one threshold for both.

   Reference: Electricity (Electrical Installations) Regulations — reg. 2, definition of extra-low voltage

6. 6An electrician reviews an RCD sensing-core arrangement on a single-phase circuit with separate L, N and PE conductors. Which conductors pass through the sensing core to compare outgoing and returning load current?

   1. A.The line and protective conductors
   2. B.The line and neutral conductorsCorrect answer: B
   3. C.The neutral and protective conductors
   4. D.The line, neutral and protective conductors

   Explanation: The guide states "A magnetic core encompasses all the current-carrying conductors of an electric circuit". Here those are L and N. PE remains outside the core so earth-fault return current creates an imbalance. Including PE could cancel that imbalance; omitting L or N prevents the intended normal-current comparison.

   Reference: Schneider Electric Electrical Installation Guide — Description of RCDs — Operating principle, current-carrying conductors and earth-fault return path

7. 7A switching-device specification requires making and breaking normal current, and making, carrying briefly and breaking a specified short-circuit current. Which defined device meets that description in the Electricity (Electrical Installations) Regulations?

   1. A.Switch
   2. B.Disconnector
   3. C.Circuit breakerCorrect answer: C
   4. D.Contactor

   Explanation: The circuit-breaker definition includes "making and carrying for a limited time and breaking an electricity current under specified abnormal circuit conditions including a short circuit". Regulation 2 defines a switch as carrying abnormal current for a limited time, without that short-circuit breaking function. The specified combination is a circuit breaker.

   Reference: Electricity (Electrical Installations) Regulations — reg. 2, definition of circuit breaker, paragraph (b)

8. 8An electrician prepares a single-line drawing for a new 30 kVA installation. What should this drawing principally show?

   1. A.The positions of fittings on the floor plan
   2. B.The internal terminal wiring of each appliance
   3. C.The mechanical dimensions of the switchboard
   4. D.The electrical circuits of the installationCorrect answer: D

   Explanation: The source states "Single-line drawing is the plan showing the electrical circuits of the electrical installation.". A single-line design drawing represents circuit connections. A location plan, appliance wiring diagram and mechanical panel drawing serve different purposes.

   Reference: EMA Handbook for Application of Electrical Installation Licence — p. 5, §6.2 footnote 7

9. 9A worker is to be appointed as a competent person to carry out work on high voltage apparatus. Whose appointment gives the worker that status under regulation 2 of the Electricity (Electrical Installations) Regulations?

   1. A.The licensee responsible for the installation
   2. B.The authorised high voltage switching engineerCorrect answer: B
   3. C.The transmission licensee supplying the site
   4. D.The Authority licensing electrical workers

   Explanation: A competent person is "a person appointed by an authorised high voltage switching engineer to carry out work on a high voltage apparatus". The appointing role is therefore the authorised switching engineer, rather than the installation licensee, transmission licensee or Authority.

   Reference: Electricity (Electrical Installations) Regulations — reg. 2, definition of competent person

10. 10Four identical motors each have a 10 kVA input rating. For this design, each motor's maximum utilisation factor is specified as 0.75 and the group's coincidence factor as 0.80. What maximum group demand should the electrician use?

    1. A.24 kVACorrect answer: A
    2. B.30 kVA
    3. C.32 kVA
    4. D.40 kVA

    Explanation: For utilisation the guide states "This factor must be applied to each individual load"; for coincidence it states "The factor ks is applied to each group of loads". Individual utilisation gives 4 × 10 kVA × 0.75 = 30 kVA; group coincidence gives 30 × 0.80 = 24 kVA. Omitting coincidence gives 30 kVA, omitting utilisation gives 32 kVA, and omitting both gives 40 kVA. The factors are supplied design assumptions, not universal Singapore values.

    Reference: Schneider Electric Electrical Installation Guide — Maximum kVA demand — Maximum utilisation and coincidence factors