2360 Electrical Installation Work Course C
QUESTION 1a
Block L will be powered by a single phase 100A distribution board.
Power
One ring circuit will provide power for the generator/switch room and substation room and will be protected by a 32A type C BS EN 60898 RCBO. An RCBO will be used because equipment could be plugged in and taken outside and it will be type C because inductive loads could be plugged in. The other ring circuit will provide power for the workshop and restroom and will also be protected by a 32A type C BS EN 60898 RCBO. An RCBO will be used because equipment could be plugged in and taken outside and it will be type C because inductive loads could be plugged in inside the workshop as well as equipment being used inside the restroom.
The roller shutter door will be wired on its own radial circuit because if it faults due to rain or strain it won’t trip out a ring circuit. It will also be protected by a 16A type C MCB to allow for start-up of the motor.
Outside Lighting
Lighting in block L will be provided by fittings using high frequency control gear to combat the stroboscopic effect around the generator.
Calculations for the five 150W high pressure sodium fitting outside lights –
150W x 5 = 750W 750W x 1.8 = 1350W
I = P = 1350W = 5.87A load current V 230V
The outside lighting radial circuit will be protected by a 10A type C BS EN 60898 RCBO, this will be required because 5.87A is too close to a 6A breaker and will be running hot. A 10A type C will be used to allow for the inductance in the discharge lighting and the 10A capacity allows for more lights to be added in the future.
Inside Lighting
The inside lighting will be protected by either a 6A or 10A type B MCB depending on the circuit. The fittings are twin 6ft fluorescent luminaires with each tube rated at 70W. The calculation to work out the maximum number of luminaires on each circuit is shown below: current per fitting = P x 1.8 (discharge lighting factor)
Block L will be powered by a single phase 100A distribution board.
Power
One ring circuit will provide power for the generator/switch room and substation room and will be protected by a 32A type C BS EN 60898 RCBO. An RCBO will be used because equipment could be plugged in and taken outside and it will be type C because inductive loads could be plugged in. The other ring circuit will provide power for the workshop and restroom and will also be protected by a 32A type C BS EN 60898 RCBO. An RCBO will be used because equipment could be plugged in and taken outside and it will be type C because inductive loads could be plugged in inside the workshop as well as equipment being used inside the restroom.
The roller shutter door will be wired on its own radial circuit because if it faults due to rain or strain it won’t trip out a ring circuit. It will also be protected by a 16A type C MCB to allow for start-up of the motor.
Outside Lighting
Lighting in block L will be provided by fittings using high frequency control gear to combat the stroboscopic effect around the generator.
Calculations for the five 150W high pressure sodium fitting outside lights –
150W x 5 = 750W 750W x 1.8 = 1350W
I = P = 1350W = 5.87A load current V 230V
The outside lighting radial circuit will be protected by a 10A type C BS EN 60898 RCBO, this will be required because 5.87A is too close to a 6A breaker and will be running hot. A 10A type C will be used to allow for the inductance in the discharge lighting and the 10A capacity allows for more lights to be added in the future.
Inside Lighting
The inside lighting will be protected by either a 6A or 10A type B MCB depending on the circuit. The fittings are twin 6ft fluorescent luminaires with each tube rated at 70W. The calculation to work out the maximum number of luminaires on each circuit is shown below: current per fitting = P x 1.8 (discharge lighting factor)