Overcurrent & Earth Fault devices

• Maths
• Further Education (Key Stage 5)

Unit 104 

Design & Installation Procedures:

Understanding Circuit Protection

ILO's

ILO 1 - Recognise the range of protective devices (fuses)

ILO 2 -  Recognise the range of circuit breakers and types.

ILO 3 - Recognise the range of protective devices (RCD's RCBO's)

Which earthing system uses an earth electrode (spike)?

1. TN-C-S
2. TN-S
3. TT
4. IT

A TT earth system relies on the consumers Earth Electrode

Which earthing system has its earthing conductor combined within the neutral and separated at the cut out?

1. TN-C-S
2. TN-S
3. TT
4. IT

What earthing system is shown?

1. TN-C-S
2. TN-S
3. TT
4. IT

ILO 1 - Recognise the range of protective devices available

Tell me something that you know about circuit protection.

Protective Devices are used in a circuit to protect from

1. Short circuits & Overloads
2. Short circuits only
3. Overloads only
4. Breaking capacity

The BS 3036 fuse is

1. Cheap
2. Good at high Fault currents
3. Replace quickly
4. Is dangerous if inserted if a fault is still on

ILO 1 - Recognise the range of protective devices (fuses)

ILO 2 - Recognise the range of circuit breakers and types.

The BS code for MCB's is

1. BS 3036
2. BS 88-2
3. BS 60898
4. BS 60947-3

TAble 7.2.2 (ii) OSG Page 80

What would a type B circuit breaker be used for?

1. Transformers & X-ray machines
2. Domestic & commercial resistive loads
3. Small Motor circuits
4. Banks of fluorescent lights

ILO 2 - Recognise the range of circuit breakers and types.

ILO 3 - Recognise the range of protective devices (RCD's RCBO's)

What type of fault does an RCD detect?

1. Short Circuit
2. Overloads
3. Over currents
4. Earth Leakage faults

A RCBO has all the properties of

1. A main switch and RCD
2. MCB & RCD
3. BS3036 & Main Switch
4. MCB & Main Switch

ILO 3 - Recognise the range of protective devices (RCD's RCBO's)

Protective device task

In small groups Match up the description with the correct protective device.

ILO's

ILO 1 - Recognise the range of protective devices (fuses)

ILO 2 -  Recognise the range of circuit breakers and types.

ILO 3 - Recognise the range of protective devices (RCD's RCBO's)

Summative Assessment

Complete MS Forms task on Protective devices.

https://forms.office.com/Pages/ResponsePage.aspx?id=NAkgcUg5KUOJSjZdQF_n8wrwqkKbC2FBlwVWModiAJtUME9HOFVUWk5GVUZTNjUzNTBKQUNDMzVPQy4u

Protective Devices

Moving Forward

Next Lesson: The effect of EFLI values & device operation under ADS