electrical safety summary 3H

• Natuurkunde
• Middelbare school
• havo, vwo
• Leerjaar 2

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Cable reel extension cord

Must be fully unrolled, otherwise the heat can not escape.

overheating is a fire hazard.

circuit overload is when the electrical wires get too hot

1. True
2. false

Overhead power lines are very thick so they have low resistance.

1. True
2. False

Short circuit or circuit overload?

1. short circuit
2. circuit overload

short circuit or circuit overload?

1. short circuit
2. circuit overload

When too many appliances are connected to a socket, the fuse will switch the current off.

1. true
2. false

Fuses

Fuses protect from short circuits and overloads. 

 Most fuses are 16A

At mains 230 V, that means max power of 16 A fuse is.

P = U x I = 230 V x 16 A

   = 3 680 Watts per fuse

Due to the electricity being split over groups in an electric installation, more appliances can be connected.

1. true
2. false

Most of the fuses in our consumer unit (meterkast) can handle max current
of

1. 3A
2. 1A
3. 16A
4. 230V

The maximum power for a group in a fuse box is found using P = U x I

1. true
2. false

For a 16 amp fuse the maximum power is 16kWh

1. true
2. false

A fuse is a safety feature to prevent a high current flowing through your body.

1. True
2. False

Too many appliances plugged into one socket can cause.

1. lights to go dim
2. overload
3. short circuit

earth = green/yellow ( think grass)

neutral =blue (think water)   live= brown

An earth leakage circuit breaker protects you from electric currents through your body

1. True
2. False

Thi

1. This plug is earthed
2. This plug is not earthed

What colour is the earth wire?

1. green/yellow
2. brown
3. blue

What colour is the live wire?

1. green/yellow
2. brown
3. blue

the blue wire is the ..

1. earth
2. neutral
3. live

If the plastic coating on a wire is damaged this can cause

1. a short circuit
2. overload
3. sparking danger

 page 74, questions

130

131 a

132 a,b

Check answers on Som

When more appliances are connected to one electric socket, the current in each appliance becomes less.

1. true
2. false

Houses are equipped with fuses to protect it from short circuits and overloads.

1. true
2. false

Fire

• When more appliances are connected to a socket,  a greater current will be used (circuit overload).
• If the current is more than 16 A - it becomes a fire hazard.
• The input cable becomes too hot and could catch fire.

The electric wires going to a light fitting, heat up a bit when in use.

1. true
2. false