“basic” earth leakage protection training course

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Schneider Electric - Residual Circuit Devices - 06/2012

“Basic” earth leakage protectiontraining course

2Schneider Electric - Residual Circuit Devices - 06/2012

Instructions to read carefully before starting

You are going to have a 25 minutes e-learning

Please follow the below instructions :

● Open the module in a slide show format

● Read the question and click a mark on your answer You can put several marks ▲ But you cannot remove a mark you already put in a box (it opens the next slide)

● Click on the button to display the answer

● Then click anywhere on the answer’s page to move on to the next slide

And….enjoy your training !


Training Objectives

●By the end of the course:

Be aware and understand current risks

Know how to protect against electrocution


Introduction

●In the UK ● What is the average of people who die each year nationally

due to unintentional electrocution?

●In France ● How many severe electric shocks still occur?

● How many deaths per year due to electrocution?

●In the US ● What is Electrocutions rank in causes of industrial fatalities?

20

4000

100(40% of such deceases involve children aged between 0 and 9)

4th 600 people die(roughly 3,600 disabling injuries occur every year)

Schneider Electric 5- Residual Circuit Devices - 06/2012

Contents

Understand the current risks

Position earth leakage protection devices in an electrical installation


Check your answer and valid


A child sticks his fingers in the holes ofa socket outlet

there's a risk of electrocution....

● 1. By short-circuit.

● 2. By direct contact

● 3. No risk of electrocution

Right Wrong




A child sticks his fingers in the holes of a socket outlet.

Can an earth leakage device protect the child from electrocution?

● Yes

● No




A child sticks his fingers in the holes of a socket outlet.

Could a circuit breaker protectthe child against electrocutionby direct contact?

● Yes

● No




Case 1: In the circuit below, the switch is open: the light is off.

Is there current in the installation?

● A. Is there current in the red conductor?

● B. Is there current in the blue conductor?

Right Wrong

The two conductors forming the cable.

Earth leakage protection device

Light (off)

Socket outlet

Light switch (open)




Case 1: The switch is open, the light is off. The red conductor is damaged upstream of the switch. A person touches the cable in that location.What happens to the person?

● 1. Nothing happens.

● 2. He feels a shock.Current goes through his body.

● 3. He feels a shock but there is no current

● 4. The light goes on.

Right Wrong




Case 1: The switch is open, the light is off. The red conductor is damaged upstream of the switch. A person touches the cable in that location.Where is there current in the installation?

● A. In the red conductor?

● B. In the blue conductor?

● C. In the light?

YES NO




Case 1: The switch is open, the light is off.A person touches the damaged red conductor. Current flows in the red conductor and in the person's body.Where does the current go next?

● 1. It returns to the source via the blue conductor.

● 2. It returns to the source via the red conductor.

● 3. It returns to the source via the earth.

● 4. It does not return to the source.

Right Wrong




● 1. Equal to 100 mA.

● 2. Less than or equal to 100 mA.

● 3. Greater than or equal to 100 mA.

● 4. Zero.

Right Wrong

Case 1: The switch is open, the light is off.A person touches the damaged red conductor.

If the current measured in the person’s body is 100mA, what is the current in the red conductor ?




Case 1: The switch is open, the lamp is off.A person touches the damaged red conductor.

If the current measured in the person’s body and in the red conductor is 100mA, what is the current in the earth?

● 1. Equal to 100 mA.

● 2. Less than or equal to 100 mA.

● 3. Greater than or equal to 100 mA.

● 4. Zero.

Right Wrong




Case 2: In the same circuit as previously, the switch is kept closed, the light is on.

Where is there current?

Right Wrong

● 1. In the red conductor?

● 2. In the blue conductor?

● 3. In the earth conductor?

● 4. In the earth?

4

3

1

2

?

?

?

?




Case 2: The light is on. It consumes 1.5 A. The red conductor is damaged. A person touches the cable in that location. He feels a shock.Where is there current?(click on each item in the diagram through which current flows)




Case 2: The light is on. It consumes 1.5 A.A person touches the damaged red conductor.A 150 mA current goes through a part of his body.

What is the current in the light, remembering that it was 1.5 A before the incident?

● 1. It doesn't change

● 2. It gets lower

● 3. It gets higher

Right Wrong

?

150 mA




Case 2: The light is on. It consumes 1.5 A.A person touches the damaged red conductor.A 150 mA current goes through a part of his body.

What is the level of current in the blue conductor?

● 1. It doesn't change

● 2. It gets lower

● 3. It gets higher

Right Wrong

1.5 A

150 mA

?




Case 2: The light is on. A person touches the damaged red conductor. A current goes through a part of his body. What is the current in the red conductor?

● 1.5 A

● 1.65 A

● 1.80 A

● 3 A

● 3.15 A

Right Wrong

1.5 A

150 mA

1.5 A

?




Let's summarise: Current characteristics in the case of electric shock by direct contactthe difference between currents in the blue conductor and the red conductor is always:

● 1. greater than or equal to the current in the human body

● 2. equal to the current in the human body

● 3. less than or equal to the current in the human body

Right Wrong

1.5 A

150 mA

1.5 A

1.65 A




As of what level can current flowing in the human body cause injuries?

discomfortno actual danger

1A

500 mA

80 mA

40 mA

10 mA

0.5 mA

heart stop

heart fibrillation

tissue burningsbreath paralysis

muscle and lung contractionno physiological damage

Personal injuries, according to level of current.

Right Wrong




Given that a current of about 40 mA can injure tissues and organs, a device intended to protect against electrocution must trip whenever

● 1. The current in the cable increases by 40 mA.

● 2. There is a 40 mA difference between the currents in the red and blue conductors.

● 3. There is an 80 mA difference between the currents in the red and blue conductors.

Right Wrong

1.5 A

1.54 A

1.5 A

40 mA




By definition, an earth leakage protection device trips if the difference in current in the two conductors is greater than its sensitivity (or pick-up level)

What is the sensitivity of an earth leakage device required to protect against electrocution by direct contact?

● 1. 30 mA

● 2. 40 mA

● 3. 1.5 A

● 4. 1.54 A

Right Wrong




With an energised part, when does the earth leakage protection device trip?

Right Wrong

● 1. Before the person touches the damaged conductor.

● 2. Shortly after the person touches the damaged conductor.

● 3. As soon as the person touches the damaged conductor.




Now, if the person is subjected to 20 mA, will the earth leakage protection device trip?

● Yes

● No




If the light is off, will the earth leakage protection device trip to ensure the person's safety?

● Yes

● No




● 1. In the human body.

● 2. In the socket.

● 3. In the power supply cables.

Right Wrong

Let's summarise: Earth leakage protection operation

The protection device prevents the current from rising above 30 mA?




Protection against electrocution by direct contact

A person touches...

Because of...

Protection is ensured by...

The current detected by the earth leakage protection device is...

The sensitivity of the protection device is...

The protection device trips…

1. An electrical part

2. A non-electrical metal part

1. A short-circuit

2. A failure of accessible insulant

1. Always an earth leakage protection device

2. An earth leakage protection device or a circuit breaker

1. Different from the current felt by the person

2. Equal to the current felt by the person

1. Always 30 mA

2. Variable according to the installation

1. Following direct contact

2. Before direct contact

Schneider Electric 52- Residual Circuit Devices - 06/2012

Contents

Understand the current risks

Position earth leakage protection devices in an electrical installation




Socket-outlets

Child's room in a new home

Do the socket-outlets comprise a risk...

● 1. High

● 2. Medium

● 3. Low

Right Wrong




Lighting

Plastic ceiling fixture in the dining room of a new home

Does this ceiling fixture comprise a risk...

● 1. High

● 2. Medium

● 3. Low

Right Wrong




Lighting

Plastic ceiling fixture in the bathroom of a new homeDoes this ceiling fixture comprise a risk...

● 1. High

● 2. Medium

● 3. Low

Right Wrong




Lighting

Plastic fixtures in the bathroom of a new homeHow can protection be provided...

● 1. A 30 mA RCD

● 2. A 100 mA or higher RCD

● 3. Earthing + a device that trips in the event of an insulation fault

Right Wrong




Circuits to be protected against electrocution by direct contact

Dry environment

Protection against direct contact

mandatory

Protection against direct contact recommended

Wall sockets

Fixed lighting / insulating casing

Wet environment

Lighting

Wall sockets

Fixed devices / metal casing




This device is an RCCB.Will it trip in case of .....

Right Wrong

● 1. …overloads

● 2. …short-circuits

● 3. …earth leakage faults




In this switchboard, which circuit should be equipped with earth leakage protection against direct contact?

Right

Wrong




Where would you position this RCCB?

● 1. In place of the circuit breaker

● 2. In addition to the circuit breaker

● 3. At the incoming point of the switchboard

Right Wrong




Where would you position the RCCB?

● 1. At the incoming point of the switchboard

● 2. On the socket-outlet circuits

Right Wrong


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“basic” earth leakage protection training course

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