What area can a ring circuit cover (Commercial)
- Thread starter Dan1983
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It is down to how you design the circuit with regard to loading - for instance a corridor of 58m² might well sustain 10 double sockets for general use eg cleaning but 10 sockets in a commerical kitchen of 25m² - probably not.....
there will be a around 35 unswitched spurs above a false ceiling which the appliance's are using 0.2amp.
the total area is around 950sqm
I was thinking of instructing my electrician to wire 3 x 2.5mm t&e ring circuits to cover this. He was talking about wiring 1 x 4mm t&e ring circuit.
I know on a domestic he normally says that 100sqm is max, but with this been commercial we are both unsure as the total load of the appliance will only come to 7amp plus the factors he applys.
Any ideas
2-3 x 2.5mm Rings
or
1 x 4.00mm Ring
the total area is around 950sqm
I was thinking of instructing my electrician to wire 3 x 2.5mm t&e ring circuits to cover this. He was talking about wiring 1 x 4mm t&e ring circuit.
I know on a domestic he normally says that 100sqm is max, but with this been commercial we are both unsure as the total load of the appliance will only come to 7amp plus the factors he applys.
Any ideas
2-3 x 2.5mm Rings
or
1 x 4.00mm Ring
Leave your electrician to decide after all, he will be signing the certificate .... 
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In commercial you would tend to use something like a canalis track with plug in tap offs.
It would certainly save a hell of a lot of work.
Ring circuits are normally used for socket outlets, not fixed loads fed via FCU's. Can tell us a little bit more about the project?
What are they feeding?
If they are fixed appliances lihe this via FCU's, then you dont use rings generally - You wire a dedicated circuit feeding what ever area you like, designing it to the anticipated load, and taking account of the length of run to ensure volt dro compliance and disconnection times.
If they are fixed appliances lihe this via FCU's, then you dont use rings generally - You wire a dedicated circuit feeding what ever area you like, designing it to the anticipated load, and taking account of the length of run to ensure volt dro compliance and disconnection times.
They are feeding very loud speakers, each speaker has its own power supply, the idea of the ring was my from electrician who did say if it was a radial the voltdrop and disconnection time would mean it would require a larger cable, thats why his original idea was a 4mm ring circuit to cover the 950sqm area,
my idea was to split it into smaller 2.5 rings to save on cost
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Returning to basics the reason why we have a 100 sq meters limit is anything over that is likely to use more then the 79 meters of twin and earth with is maximum with 2.5mm cable to keep within volt drop of 5% required by BS7671:2008. By using 4mm you can use 130 meters on a ring and by reducing the MCB to less than 32 amp it can be extended further 4mm with 20 amp MCB would extend it to 204 meters.
With 950 sq meters even this is likely not to be long enough and multi-feeds are likely to be required but of course one can easy end up using whole of cable allowance to feed first socket and it had to be carefully planned and very likely sub boards with be required to allow even heavier feeds to used.
Planning does require some maths as well as simple rule book and I would advise you leave this to the electrical engineer who is planning the work.
Reading what you have said I wonder if this is for lighting? If so then the lengths given are wrong that 204 meters for 4mm at 20 amps drops to 125 meters just above a false ceiling at 0.2 amp i.e. 46 watt sounds like lighting if so unless using HF units florescent then with std florescent I would allow 60 watt for each 40 watt unit as I found to my cost they use more than rated voltage.
Eric
With 950 sq meters even this is likely not to be long enough and multi-feeds are likely to be required but of course one can easy end up using whole of cable allowance to feed first socket and it had to be carefully planned and very likely sub boards with be required to allow even heavier feeds to used.
Planning does require some maths as well as simple rule book and I would advise you leave this to the electrical engineer who is planning the work.
Reading what you have said I wonder if this is for lighting? If so then the lengths given are wrong that 204 meters for 4mm at 20 amps drops to 125 meters just above a false ceiling at 0.2 amp i.e. 46 watt sounds like lighting if so unless using HF units florescent then with std florescent I would allow 60 watt for each 40 watt unit as I found to my cost they use more than rated voltage.
Eric
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