Nt1310 Unit 5

Question 1(a)

Power
A 100a Distribution Board will be used to power Block L. A ring circuit will provide power to the substation room and Generator/switch room (labelled Sockets, Generator/Switchroom). It will be protected by a 32A BS EN 60898 type C RCBO. The RCBO type C is used as equipment could either be plugged in from outside or attached to an inductive load. Another ring circuit will provide power for the workshop and restroom (labelled Sockets, Workshop/Restroom), this will also be protected by a 32A BS EN 60898 type c RCBO as again, equipment could be plugged in from outside or attached to an inductive load, as well as equipment being used within the restroom. The Electric Roller Shutter Door (labelled Motor Door) will be wired
on its own radial circuit as if it faults due to wear it will not trip out a ring circuit. It will be protected by a 16A type D MCB to allow for the motor.

Outside Lighting

The Block L outside lighting will be on a radial circuit protected by a 10A type c BS EN 60898 RCBO, this will be used to allow for the inductive discharge lighting and the 10A capacity for future lighting to be added.
Calculations:
150W x 5 = 750W 750W x 1.8 = 1350W (1.8 discharge lighting factor)
I = P = 1350W = 5.87A load current V 230V

Inside Lighting
The inside lighting fittings will be twin 6ft fluorescent luminaires protected by either a 6A or 10A type B MCB circuit depending, with each tube rated at 70W. They will be divided into five circuits. current per fitting = P x 1.8 (discharge lighting factor) V

current per fitting = (2 x 70W) x 1.8 230V

current per fitting = 1.1A

number of fittings = __MCB rating___ current per fitting

number of fittings = _6A_ = 5.45 1.1A

number of fittings = 10A = 9.09 1.1A

The 6A MCB will have 5 fittings and the 10A MCB will have 8 fittings so that the breaker does not run hot.

Diversity Calculations

All following diversity factors are from Table A2, BS7671 On Site Guide, (OSG).
Circuit 1: Sockets, Workshop, Rest Room. Ring Final circuit. 32A
Diversity factor = 1
32A x 1 = 32A

Circuit 2: Sockets, Generator, switch room. Ring Final Circuit. 32A
Diversity Factor = 0.5 (50%)
32A x 0.5 = 16A

Circuit 3: Motor Door. Motor 16A
I = P = 3000W = 13.04A V 230V
Diversity Factor = 1
13.04A x 1 = 13.04A

Circuit 4: Outside Lighting
150 x 5 = 750W 750W x 1.8 = 1350W I = P = 1350W = 5.87A V 230V
Diversity Factor = 0.9 (90%)
5.87 x 0.9 = 5.28A

Circuit 5: Switchroom Lighting (8 70W Double Fluorescent Fittings)
I = P = (70 x 2 x 8 x 1.8) = 8.77A V 230V Diversity Factor = 0.9 (90%) 8.77A x 0.9A = 7.89A

Circuit 6: Switchroom Lighting (6 70W Double Fluorescent Fittings)
I = P = (70 x 2 x 6 x 1.8) = 6.57A V 230V
Diversity Factor = 0.9 (90%)
6.57A x 0.9 = 5.91A

Circuit 7: Substation Lighting (5 70W Double Fluorescent Fittings)
I = P = (70 x 2 x 5 x 1.8) = 5.48A V 230V
Diversity Factor – 0.9 (90%)
5.48A x 0.9 = 4.93A

Circuit 8: Workshop Lighting (3 70W Double Fluorescent Fittings)
I = P = (70 x 2 x 3 x 1.8) = 3.29A V 230V
Diversity Factor = 0.9 (90%)
3.29A x 0.9 = 2.96A

Circuit 9: Workshop Lighting (3 70W Double Fluorescent Fittings)
I = P = (70 x 2 x 3 x 1.8) = 3.29A V 230V
Diversity Factor = 0.9 (90%)
3.29A x 0.9 = 2.96A

Circuit 10: Workshop Lighting (3 70W Double Fluorescent Fittings)
I = P = (70 x 2 x 3 x 1.8) = 3.29A V 230V
Diversity Factor = 0.9 (90%)
3.29A x 0.9 = 2.96A

Circuit 11: Restroom and Toilet Lighting (4 70W Double Fluorescent Fitings)
I = P = (70 x 2 x 4 x 1.8) = 4.38A V 230V
Diversity Factor = 0.9 (90%)
4.38 x 0.9 = 3.94A

Every Circuit design and diversified current has been calculated.
This is to create the board schedule for the lighting and power distribution board. The board’s maximum demand is 100A so the diversified current cannot exceed this. A board schedule can be made showing all circuits protective device, design & diversified current, and the total diversified current.

CircuitNo. | CircuitDescription | No. Of Points | Protective Device Rating (A) | Protective Device Type | Design Current(A) | Diversity Factor | Diversified Current(A) | 1 | Ring Final(workshop, restroom) | 10 | 32 | C | 32 | 1 | 32 | 2 | Ring Final(substation/generator/switchroom) | 4 | 32 | C | 32 | 0.5 | 16 | 3 | MotorDoor | 1 | 16 | C | 13.04 | 1 | 13.04 | 4 | Lighting - Outside | 5 | 10 | C | 5.87 | 0.9 | 5.28 | 5 | Lighting - Switchroom | 8 | 10 | B | 8.77 | 0.9 | 7.89 | 6 | Lighting - Switchroom | 6 | 10 | B | 6.57 | 0.9 | 5.91 | 7 | Lighting - Substation | 5 | 6 | B | 5.48 | 0.9 | 4.93
| 8 | Lighting - Workshop | 3 | 6 | B | 3.29 | 0.9 | 2.96 | 9 | Lighting – Workshop | 3 | 6 | B | 3.29 | 0.9 | 2.96 | 10 | Lighting – Workshop | 3 | 6 | B | 3.29 | 0.9 | 2.96 | 11 | Lighting – Restroom/Toilets | 4 | 6 | B | 4.38 | 0.9 | 3.94 | TOTAL 97.87A