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C&G 2365-211/601 > Hazards > Flashcards

Hazards Flashcards

1
Q

Define a hazard

A

A potenial source of harm or adverse health effect on a person or persons

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2
Q

Define a risk

A

the likelihood that a person may be harmed or suffer adverse health effects if exposed to a hazard

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3
Q

What are the four specific hazards associated with installation of electrical systems?

A
  • Electric shock (direct & indirect)
  • Burns
  • Fires
  • Explosions
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4
Q

Define an electric shock

A

The physiological reaction, sensation or injury caused by electric current passing through the (human) body

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5
Q

What are the direct dangers of an electric shock?

Three things

A
  • stoppage of breathing
  • stoppage of regular heart rhythm
  • burns
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6
Q

What are some examples of secondary events which could result in indirect danger from an electric shock?

A
  • Falls
  • Fires
  • Explosions
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7
Q

Roughly what is the smallest amount of current that a human can percieve?

A

1 milliamp (1mA)

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8
Q

What amount of current can seize the human heart muscle?

A

80 milliamps (80 mA)

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9
Q

What is electrocution?

A

A fatal electric shock

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10
Q

What is a direct contact electric shock?

A

When a person recieves an electric shock as a result of touching live conductive parts

(Under non-fault conditions)

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11
Q

What is an indirect contact electric shock?

A

When someone recieves an electric shock from conductive parts which are not normally live.

(Under fault conditions)

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12
Q

What does the International Electrotechnical Commision (IEC) recommend to prevent direct contact electrical shocks?

A

Degrees of ingress protection (IP)

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13
Q

What makes electrical burns so dangerous?

A

They may not be visible on the skin, there may be a small mark where the current entered the body but there could be severe damage to internal tissues and organs.

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14
Q

What could happen if a short circuit occurs in an electrical installation?

A

It could result in a spark, which could ignite flammable material or gases, causing a fire or an explosion.

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15
Q

What defines an explosive atmosphere?

A

A mixture of gases, vapours, mist or dust in the air in which combustion spreads to the entire unburned mixture.

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16
Q

What does the term intrinsically safe mean?

A

That the electrical installation cannot ignite the potentially explosive atmosphere.

At least in the design/ installation stage, could be tampered with.

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17
Q

Define the term intrinsically safe

A

Intrinsically safe equipment and wiring shall not be capable of releasing sufficient electrical or thermal energy under normal or abnormal conditions to cause ignition of a flammable or combustible atmospheric mixture in its most easily ignitable concentration.

Basically, it has to be designed so that it physically cannot use enough energy to create a sufficient enough spark to cause a fire or explosion.

18
Q

True or false:
The mark of a skilled and conscientous tradesperson is a tidy and organised work space, free from trip hazards

A

True.
Preventing fires or trips is an excellent way of working.

19
Q

Fill in the blanks:

Many things can be a ___ hazard in the work place, such as:
* ___ discarded tools, equipment and materials
* Spilled ___ (such as ___ and lubricants)
* Trailing ____ and welding ____
* Uneven _____

A
  • trip
  • carelessly
  • materials
  • oils
  • cables
  • hoses
  • terrain
20
Q

Under what kind of conditions are the potential hazards of electricity at work at thier highest?

A

In harsh conditions

21
Q

Name four examples of harsh conditions

A
  • Damp/ wet surroundings
  • Out of doors
  • Cramped spaces with a lot of earthed metalwork
  • Where items of equipment are at higher risk than others
22
Q

Which three parts of extension cables are particularly liable to damage?

A
  • The plugs/ sockets
  • The electrical connections
  • The cable itself
23
Q

Under which regulations should new electrical systems be installed/ maintained?

A

BS7671: 2018 Requirements for Electrical Installations

24
Q

True or false:
Electrical equipment used in potentially explosive atmospheres doesn’t require special attention/ advice.

A

False.
U want boom?
Boom bad.

25
Q

True or false:
The equipment used must be suitable for its purpose and environment to reduce potential hazards.

A

True.
Considerations must be made for the type of equipment as well as its suitability for where it will be located.

26
Q

True or false:
Electrical equipment must be provided and maintained in a safe manner for a competant person to use.

A

False.
It must be safe for anyone to use, regardless of expertise.

27
Q

True or false:
Existing installations should be properly maintained.

A

True.
Obviously.

28
Q

When using portable equipment, which plug sockets should be used?

A

The closest available, so it can be shut off quickly in the event of an emergency.

29
Q

If the plug is not a “moulded-on” type, what must be checked?

Two things must be checked and ensured

A
  • all the wires are properly connected
  • that the wires are in the correct terminals in the plug top
30
Q

When using machinery, what should be nearby and accessible?

A

A clearly identified switch to cut off power in an emergency

31
Q

True or false:
Using adapters is completely fine whilst working on site

A

False.
Enough sockets should be provided, as using too many adapters is a fire hazard, overloading them is dangerous.

32
Q

Which sections of damaged cable should be replaced?

A

The entire section of cable

33
Q

Which part of cables should be firmly clamped down to prevent them from being pulled out?

A

The ends of flexible cables, particularly the CPC.

34
Q

How should lengths of cable be connected together?

A

By using appropriate and proper connectors

35
Q

Where should RCDs be used?

A

Outside of the Equipotential Zone

36
Q

Complete the following sentence:

Risks can be reduced by using ___, ____, ____ or battery ____ tools.

A
  • air
  • hydraulic
  • hand
  • powered
37
Q

What voltages can temporary lighting be run at to improve safety?

A
  • 12 volts
  • 25 volts
  • 50 volts
  • 110 volts
38
Q

True or false:
Battery powered tools are the safest tools to use on site

A

True.
Less cables and wires trailing means less risk of a slip or trip

39
Q

What does CTE stand for?
What voltage of tool does it help operate?

Bonus point if you can describe what it do

A
  • Centre-Tapped-Earth
  • 110V

It’s a safety feature of a lot of sites and mains power, in the site version it is referred to as a 55V-0–55V system, where the centre of the second winding is connected directly to the Earth.

40
Q

What is the “usual” rated tripping current of an RCD?

A

Not more than 30mA

41
Q

What is the best place for an RCD?
Where else could it be placed if this is unavailable?

A
  • Main circuit board
  • Plug top device
42
Q

True or false:
Trip hazards are often easily prevented

A

True.
It is the responsibility of everyone to keep their working area tidy and free of any potential trip or slip hazards.

C&G 2365-211/601 (21 decks)

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