Element 10

Question 1

An advantage of a residual current device is that, in the event of an electrical shock, it offers protection to a person. True to false?

Answer 1

True. An RCD acts quickly and offers protection to a person in the event of an electric shock

Question 2

How does a fuse act as a protective system?

Answer 2

A fuse acts a as weak link in a circuit by melting if the current exceeds the safe limit

Question 3

What are the factors which influence the severity of an electric shock?

Answer 3

• Voltage
• Current
• Current path
• Contact time
• Body resistance
• Environment

Question 4

A properly rated fuse offers protection to a person. True or false?

Answer 4

False. A fuse only protects the equipment and the circuit

Question 5

Only a fully qualified electrician can work on an electrical system. True or false?

Answer 5

False. Any person who works on electrical systems has to be “competent” - not necessarily “electrically qualified”.

Question 6

What are the limitations of Portable appliance testing (PAT)?

Answer 6

• Equipment is only safe at the time of testing completion (e.g. may develop fault soon after)
• A label confirming PAT testing has been carried out may give a user a false sense of security (e.g. the user may not think a visual inspection is necessary before use)
• Any “illegal” items (such as a radio brought in from home) will not be on a PAT schedule

Question 7

What are the main hazards and risks of working with electricity?

Answer 7

• Electric shock and burns from contact with live parts
• Injury from exposure to arcing
• Fire from faulty electrical equipment or installations
• Explosion caused by unsuitable electrical apparatus or static electricity igniting flammable vapours or dusts, for example in a spray paint booth

Question 8

HSE guidance document GS6 offers guidance on avoiding danger from underground services. True or false?

Answer 8

False. HSE document GS6 (“Avoiding danger from OHP”) provides guidance when working near or under overhead powerlines. HSG47 offers guidance when working near underground power cables.

Question 9

Reduced voltage means less risk. True or false?

Answer 9

True. A 110v CTE transformer offers greater protection from shock than 240v.

Question 10

What are the conditions and practices that lead to accidents with portable electrical equipment?

Answer 10

• Using equipment in inappropriate conditions
• Using damaged equipment (s a particular problem on construction sites where the harsh operating conditions mean there is a high probability of mechanical damage)
• Damaged caused by dragging equipment by the cable
• Inadequate or damaged cable connections
• Inadequate maintenance and/or failure to properly check equipment before use
• Wrongly rated fuses
• Using damaged equipment