Electrical Maintenance Test (2 Day Course)


1. What is the lowest level of current that could be fatal (fibrillation of the heart)

A.   1A

B.   100mA (0.1A)

C.   10A

D.   0.5A (500mA)

2. For your own safety, before working on equipment to replace parts you must

A.   Isolate the supply

B.   Switch off the equipment

C.   Ensure you are earthed

D.   Ensure that you are wearing rubber soled boots or shoes

3. The voltage between two phases (eg L1 to L2) of a three phase supply is 

A.   110V

B.   230V

C.   400V

D.   600V

4. The purpose of earthing is to

A.   Provide a safe current path

B.   Trip a circuit breaker

C.   Ensure touchable conducting surfaces cannot become live

D.   Protect equipment from damage

5. Which of the following would not be a symptom of a current overload

A.   An RCD trips out

B.   A cable becomes overheated

C.   A fuse blows

D.   An MCB trips out

6. What is the purpose of a 30mA RCD (Residual Current Device)

A.   Prevent over-current (excessive current)

B.   Reduce the voltage to safe level

C.   Prevent harmful electric shock

D.   Trip out the supply in the event of an overload

7. Resistance of the human body is generally

A.   Very high

B.   insignificant

C.   Very low

D.   Variable and unpredictable

8. If a person is receiving an electric shock and cannot let go of the live part you should firstly

A.   Pull them away as quickly as possible

B.   Give them  mouth to mouth resuscitation

C.   Use a non conducting item to separate them from the supply

D.   Disconnect the supply immediately

9. Typically the voltage in the UK lies somewhere between 

A.   200 – 250V

B.   230V – 250V

C.   220V – 240V

D.   216V – 253V

10. The purpose of an MCB/overload is to

A.   Prevent electric shock

B.   Prevent too much current flowing in a circuit

C.   Reduce the supply voltage

D.   Provide a convenient method of turning off a circuit

11. 230V has to be considered as

A.   Safe to touch

B.   A voltage that will always kill a person

C.   Nothing to worry about

D.   A voltage that has the potential to harm or kill

12. Which ONE of the following statements is TRUE

A.   Poor connections can cause heat to be produced

B.   Excessive resistance in a circuit will trip out an MCB circuit breaker

C.   A transformer converts AC into DC

D.   Contactors prevent overloads in circuits

13. Which of the following MCBs would be used in the supply to a small/medium sized motor

A.   Type D

B.   Type A

C.   Type C

D.   Type B

14. When measuring resistance in a circuit, the circuit must 

A.   Be turned on (have power applied to it)

B.   Be turned off (dead)

C.   Have been switched on recently

D.   Be capable of being switched of quickly in a an emergency

15. There maximum voltage that is UNLIKELY to harm a person is

A.   24V

B.   110V

C.   50V

D.   230V

16. Working on live equipment is

A.   Prohibited by the Electricity at Work Regulations 1989

B.   Allowed at all times

C.   Allowed in cases of emergency

D.   Allowed when it is unreasonable for the circuit to be dead

17. When testing the resistance of the windings of a three phase motor, the resistances should be

A.   Greater than 10Ω for each winding

B.   The same as the power rating of the motor

C.   The same for all windings

D.   Not greater than 100Ω

18. Three important parameters on a DC PSU (Power Supply Unit) are

A.   Size, Input voltage, input frequency

B.   Output voltage, input frequency, input current

C.   Output voltage, input voltage, input frequency

D.   Input voltage, output voltage and output current

19. When replacing a contactor, an important parameter to look for is the 

A.   Coil operating voltage

B.   Resistance of the coil

C.   Manufacturer

D.   Number of contacts

20. The resistance of the secondary windings of a step down transformer will be

A.   Greater than the primary windings

B.   Equal to the primary windings

C.   Less than the primary windings

D.   Not greater than 100Ω