What about cooker circuits?
10A RCBO for a lighting circuit...?
- Thread starter sarahw
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I have already quoted the reg and Paul is right it says "installation" not "circuit".
However most modern houses if you count the MCB's ratings are well over the diversity shown in the guides and we all know it is very rare for the supply fuse to blow.
If the question was "My 6A MCB keeps tripping when I leave all the lights on" ones answer would be completely different to "Is the electrician allowed to change the 6A MCB to a 10A RBCO within the regulations" and to the latter question I would say if it has ceiling roses no. To the former one would suggest power reduction by use of energy saving bulbs or splitting supply or moving some items to another supply maybe using a FCU.
I would say it is very unlikely that ceiling roses are not used as junction boxes so very likely her dad is spot on?
P
Paul_C
They're an exception which allow diversity to be applied to the branch circuit.
Paul_C said:
Which regulation says you may apply it to final circuits serving cooking appliances but not lighting?
The only reg I can find which deals with diversity is 311.1, and that does not support the use of it on individual circuits at all.
The only reg I can find which deals with diversity is 311.1, and that does not support the use of it on individual circuits at all.
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Not sure I follow but as already agreed with GaryMo the OSG is a guide and not a reg. However I would consider it an authoritative guide and if says to do something then that's pretty much allowed.
yes it does.ban-all-sheds said:
Again, down to interpretation:
311.1 - For economic and reliable design, the maximum demand of an installation shall be assessed. In determining the maximum demand of an installation or part thereof, diversity may be taken into account.
An individual circuit forms part of an installation.
311.1 - For economic and reliable design, the maximum demand of an installation shall be assessed. In determining the maximum demand of an installation or part thereof, diversity may be taken into account.
An individual circuit forms part of an installation.
P
Paul_C
Hmmm...... Has the specific rule about not allowing diversity on a final circuit been removed at some point then?
Has the specific rule about not allowing diversity on a final circuit been removed at some point then?
Diversity can and should be used for circuit design, as if not, it would result in cables and protective devices which were grossly oversized.
While a property with standard bayonet lampholders could have 100W in each one and they could all be switched on at the same time, this is unlikely.
In this instance diversity is not required anyway, as the downlighters will be 50W maximum, and even if all of the lights were on, the total load is still under 6A.
Same applies to cooker circuits - design for the total load of all elements all being on would end up with a cooker circuit of 16mm or even more.
A circuit with 10 socket outlets could have nearly 30kW of items connected to it. No one is likely to consider installing cables suitable for that kind of load, and the cables wouldn't fit into the socket terminals anyway.
While a property with standard bayonet lampholders could have 100W in each one and they could all be switched on at the same time, this is unlikely.
In this instance diversity is not required anyway, as the downlighters will be 50W maximum, and even if all of the lights were on, the total load is still under 6A.
Same applies to cooker circuits - design for the total load of all elements all being on would end up with a cooker circuit of 16mm or even more.
A circuit with 10 socket outlets could have nearly 30kW of items connected to it. No one is likely to consider installing cables suitable for that kind of load, and the cables wouldn't fit into the socket terminals anyway.
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Other than appendix I find diversity in 311.1 and 523.7 only. There is something about it in Appendix 12 but nothing to say where you can't use it in main section.
However question is can one fit a 10A RBCO to a lighting circuit and answer is still not if it has ceiling roses rated at 6A.
It has already been stated the capacity of the 6A MCB is unlikely to be exceeded and it seems maths is not the strong point of electrician involved except that the more he does the more he's paid. Or did he not have a 6A RCBO in his van so wanted to fit what he had in stock?
However question is can one fit a 10A RBCO to a lighting circuit and answer is still not if it has ceiling roses rated at 6A.
It has already been stated the capacity of the 6A MCB is unlikely to be exceeded and it seems maths is not the strong point of electrician involved except that the more he does the more he's paid. Or did he not have a 6A RCBO in his van so wanted to fit what he had in stock?
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