Intial Verification (Before Testing)

Question 1

1. Connection of conductors

Answer 1

Ensure all connections are mechanically secure
- use a tug test
- use a torque driver for the connections
- visual examination
- connection too tight causing mechanical damage at the cable
Poor connections can cause arcing, will give a high resistance on r1+r2 test

Question 2

2. Identification of conductors

Answer 2

All conductors to be numbered or coloured to ID the cable
- T&E CPC must have green and yellow sleeving
- The use of sleeving or tape to ID strappers or switch wires
Used to correctly ID line, neutral and CPC for termination conductors.

Question 3

3. Routing of cables

Answer 3

Cables should be placed behind walls in straight lines, cable on the surface should be protected in trunking or conduit.
- Visual inspection of trunking/conduit to ensure it is complete and there is no damage
- Cables behind walls should be examed during consturction
- Cable in a wall must be within 150mm of a corner or ceiling

Question 4

4. Selection of conductors

Answer 4

Cables should be selected to ensure they can carry the current to the load without an overload of excessive volt drop
- Volt drop 3% for lights, 5% for everything else
- Check protective device’s current against the current carrying capacity of the cable
- Check the length of the run with the mV/A/M value of the cable and the load current

Question 5

5. Connection of Single Pole Devices

Answer 5

Visual inspection to ensure on single pole circuits the line conductor (not the neutral) is switched)

Question 6

6. Correct connection of accessories (Polarity)

Answer 6

Visual inspection to ensure the polarity of any connected accessory is correct

Question 7

7. Presence of fire barriers (not for domestic)

Answer 7

Visual inspection of barriers used to block holes for cable runs between areas of buildings that require fire barriers

Question 8

8. Methods of protection agains electric shock A

Answer 8

• SELV - 50v AC without an earth
• PELV - 50v AC or below with earth
• Visual inspection of transformer to ensure it is correctly rated
• Visual inspection to ensure correct earthing arrangement is present
• Double insulation - 2 layers of PVC, visual inspection to ensure there are no cracks

Question 9

8. Methods of protection agains electric shock B - Basic Protection

Answer 9

• Physical inspection of insulation of live parts and insulation around the cable to ensure there is no exposed conductor
• Visual inspection to ensure adequate protection by barrier or enclosure and protection of PVC single core cable using trunking or conduit, preventing them from being touched
• Visual inspection to ensure enclosure is complete and undamaged
• Physical inspection to ensure there are barriers over exposed bars preventing touch

Question 10

8. Methods of protection agains electric shock C - Fault Protection

Answer 10

Alternative sources
- Ensure there are no alternative sources such as solar panels, make sure there is additional isolation if they are present
Setting of protective devices
- Ensure the correct circuit breaker and overload rely are present
- Ensure the correct rating of protective devices is used
- Overload relys should be set to the current rating of the motor

Question 11

Automatic disconnetion of the supply

Answer 11

Earth fault loop impedence
- A low impedence is needed to give a high fault current, the large over current flows through the circuit rupturing the protective device in 0.4 or 5s
- If earth loop impedance value is to high the circuit will either take to long to trip or won’t trip at all

Question 12

Earthing arrangements

Answer 12

Earth electrode - visual inspection of earth rod
Earthing conductor - earth supply from supply company
Circuit protective conductor - visual inspection of CPC
Protective bonding conductor - visual inspection
Supplementary bonding conductors - visual inspection
Exposed conductive parts are connected to earthing arrangements - visual inspection

Question 13

Electrical seperation

Answer 13

Protection through a transformer where the earth stops on the primary side
- must be used in bathrooms

Question 14

Additional protection RCDs

Answer 14

must be a 30mA RCD - visual inspection

Question 15

Prevention of mutual detrimental influence

Answer 15

Visual inspection to ensure -
Seperation of electrical cables and telecom cables
Consumer units should be away from water pipes

Question 16

Presence of appropriate devices for isolation and switching correctly located

Answer 16

visual inspection to ensure devices are there and appropriately located

Question 17

Presence of undervoltage protection devices (not domestic)

Answer 17

For specalist areas, particularly used with 3ph motors, when these motors are switched on they can induce a volt drop which would increase current potentially tripping the supply breaker, these sense the volt drop and trip before it happens.
Visual inspection

Question 18

Labelling of protective devices, switches

Answer 18

Visual inspection to ensure correct labelling is in place

Question 19

Selection of equipment and protective measures appropriate to external influences

Answer 19

Entrances for vermin should be filled particularly holes for cables to enter buildings

Question 20

Adequacy of access to switchgear and equipment (including consumer unit)

Answer 20

Access to switch gear should not be restricted, doors open to 90
Consumer unit front face should be able to be open and be removed

Question 21

Presence of danger notices and other warnings

Answer 21

Visual inspection of test date labels, earth clamps label, voltage warning for 400v or higher

Question 22

Presence of diagram, instructions and similar info

Answer 22

3 main drawings - lighting, power, containment
OM (operating and maintenance manual)

Question 23

Selection and erection of wiring systems

Answer 23

Visual inspection to ensure trunking, conduit or containment has been correctly installed and that metal conduit or trunking has an earth link.

Question 24

Selection and installation of suitable surge protection device

Answer 24

visual inspection to ensure SPD is there is necessary.