5.2 Control Measures When Working with Electrical Systems or Using Electrical Equipment in All Workplace Conditions

Question 1

The legal framework for controlling the risks of working with electrical equipment and circuitry are contained within the…

Answer 1

Electricity at Work Regulations 1989 (EAWR)

Question 2

The general duties of the Electricity at Work Regulations 1989 require the employer, so far as is reasonably practicable to ensure that:

Answer 2

 Electrical systems are constructed and maintained so as not to give rise to danger;
 Every work activity, including operation, use and maintenance of a system and work near a system, is carried so as not to give rise to danger; and
 Protective equipment is suitable for the use for which it is provided, maintained in good condition and properly used.

Question 3

placing PVC insulating tape over a circuit breaker to prevent inadvertent switch-on is a safe means of isolationTrue or False?

Answer 3

False

Question 4

What term found in the EAW regs. is being described below:

the ability of the equipment to withstand the thermal, electromagnetic and electro-chemical effects of the electrical currents which might be expected to flow through them.

Answer 4

‘strength and capability’

Question 5

Precautions are required to prevent danger when a conductor (other than a circuit conductor) becomes charged as a result of the use of a system, or a system fault. What are the four main precautions?

Answer 5

(a) earthing
(b) fuses, MCB’s, RCD’s
(c) double insulation
(d) use of safe voltages

Question 6

What word belongs in the [_______] below:

A [_______] contains a piece of wire that melts easily. If a fault in an appliance causes too much current flow through the [_______] the wire heats up until it melts and breaks the circuit. The [_______] is designed to protect the wiring and the appliance if a fault occurs. [_______] operate too slowly to provide protection against electric shock and are easy to replace with incorrectly rated fuses or other metal “bridges” such as nails, screws or bolt

Answer 6

Fuse

Question 7

What word belongs in the [_______] below:

An [_______] does the same job as a fuse, but works in a different way. A spring-loaded push switch is held in the closed position by a spring-loaded soft iron bolt. An electromagnet is arranged so that it can pull the bolt away from the switch if the current increases beyond a set limit. This releases the push switch into the open position and breaks the circuit.

Answer 7

MCB (mini circuit breaker)

Question 8

What word belongs in the [_______] below:

[_______] is a generic term which embraces a range of related devices. An [_______] works by constantly monitoring the current flowing in the live and neutral wires supplying a circuit or piece of equipment. Under normal circumstances, the current flowing in the live and neutral wires is equal. When an earth leakage occurs due to a fault an imbalance occurs. The imbalance is detected by the [_______], which automatically cuts off the power before injury or damage can result. [_______] for protecting people have a rated tripping current (sensitivity) of not more than 30 milliamps (mA) and a non-adjustable rated operating time of 200 milliseconds (ms) at a test current of 30 mA, and 40 ms at 150 mA.

Answer 8

RCD (residual current device)

Question 9

The use of 110V CTE (Centre tapped to earth) supply (Reduced Low Voltage) is advocated in the UK for harsh environments such as construction sites. The centre tap to earth ensures that in a single phase system the maximum voltage to earth is only how many volts?

Answer 9

55V

Question 10

Work on or near live conductors should be the exception to the rule. Live working should only be permitted if:

Answer 10

Unreasonable to be deadReasonable to be liveSuitable precautions have been taken

Question 11

A safe system of work for working near buried services has four basic elements:

Answer 11

 planning the work;
 plans;
 cable-locating devices; and
 safe digging practices

Question 12

The following hierarchy of precautions should be applied to work at or near overhead power lines:

Answer 12

 avoid working under or near overhead lines;  divert overhead lines clear of the work area or;  make lines dead while the work is in progress;  work around the live overhead lines using appropriate precautions.

Question 13

In any accident involving electricity the first priority is

Answer 13

isolate the power supply

Question 14

The frequency of periodic inspection and testing of fixed installations is determined taking into account:

Answer 14

 the type of installation;
 its use and operation;
 the frequency and quality of maintenance; and
 the external influences to which it is subjected