Discuss diversity on lighting circuit? in the Electrical Forum area at ElectriciansForums.net

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sima24

Hi guys, was wondering if its acceptable to allow diversity to a lighting circuit. Customer has about 8 lights on the downstairs lighting circuit, but wants 12 spots putting into the kitchen. Now using the 100w per lighting point takes total current to 8.5A with all lights on at 100w. Now all the lamps are not 100w, but would i still have to split it into 2 6a circuits or can i apply diversity? Thanks
 
No diversity, but you can simply ensure that the proposed load can be carried by the circuit (cable and ocpd). You will also have to consider the need for rcd protection for the circuit, if it is not already in place.
Regards.
 
Why not use 50w instead of 100w when calculating for the kitchen spots, as I'm guessing the max wattage would be 50w per lamp.
i know your ment to use 100 but common sense tells me to use 50 for gu10 downlights
 
As Will says, apply a bit of common sense.
 
No diversity, but you can simply ensure that the proposed load can be carried by the circuit (cable and ocpd). You will also have to consider the need for rcd protection for the circuit, if it is not already in place.
Regards.

Why a need for a RCD? If he uses the existing switch drops and simply makes changes above the ceiling I'd suggest they aren't required.
 
Also if when you consider load on a lighting circuit can you actually buy/fit 100w bulbs any more. As others have said a dose of common sense is required.

The same can also be said about calculating maximum load when housed now often have a 10 way board rather than a 6 way board.
 
Thanks, i understand everyone would use common sense, but i changed the board in safe property a while ago and going to use for my elecsa inspection, not sure if they would use common sense or still thoroughly to the regs
 
You can apply common sense and diversity to lighting circuits-

12 x 100W = 5.2A
12 x 50W = 2.6A

So based on your information and assuming you will install 12 x 50W GU10's and that all the other points in the house are 100W or less, I would reduce your total load by 2.6A to 5.9A and then apply diversity of 66% to the 5.9A = 3.9A

Obviously all subject to satisfactory test results to existing circuit.
 
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Guys, I might be getting this all wrong, but this talk of "diversity" is, I think, misplaced.

Diversity is used/applied when calculating the maximum demand for an installation, and is applied to the total current deman of individual circuits (e.g 66% of total current demand for lighting).

The OP has essentially asked if by increasing the number of lights/downlighters, he is going to have a problem with the load on the circuit. As others have pointed out, the circuit will have been designed at 100W per light (single pendant/room) and of course, typically modern lights have lower wattage and may even be led. So it's simply about checking the new total load against the ccc of the cable and the ocpd.

Not looking to start an argument - just want to ensure I've not been misunderstanding diversity all these years!!!!:bigcry:
 
To apply diversity to a lighting circuit is to assess the likelyhood of all the lights being on at the same time for long periods , if this is unlikely then you can apply the 66% of full load figure that the OSG suggests for domestic installations.
Commercial installations , such as offices , often have whole areas of the building lit up for long periods thus only a small diversity adjustment can be made eg 90% of full load.
The actual wattage of the lights is what you use to calculate the circuit design current , then you apply diversity after reaching this figure.
 

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