1mm or 1.5mm T&E
- Thread starter New2Game
- Start date
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1mmsq is pretty much standard for a lighting circuit, it's rated to 14A and is more than adequate for the 6A breaker that normally protects a lighting circuit and is far easier to wire with. You would only need to use 1.5 when factors apply that will de-rate the cable enough to require a larger conductor, on a large lighting circuit where volt drop and/or diversified load may become a problem, or when it's what you happen to have kicking around 
I never use 1.0mm². Ever.
For the price difference you might as well, and then the installation is future proofed too.
<edit, 'We' changed to 'I'>
For the price difference you might as well, and then the installation is future proofed too.
<edit, 'We' changed to 'I'>
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It,s ridiculous to say we never use 1.0mm cable, as the size of cable used in any circuit is dependant on the load and the cable used.
while it always aviseable to allow for a small further developments, it only practical to use your common sense in accessing further expansion. if the circuit is never going to increase beyond the rated cable value, thats good enough. it is also the responsibity of the person expanding the circuit to ensure the carrying capacities are surficent for the planed expansion.
Also the carrying capacity cables vary because the capacity is determined by not only the cross sectional area of the conductor, but also the insulation ie, mineral insulated is higher rated than PVC.
A simple way to assess the required load is add all the wattages together
double the wattage of any florescent fittings and remember that all the fittings using mains voltage ( ie small spots GU10 etc ) count as total load. Allow 5amps per 1000watts and this will give you some surplus.
while it always aviseable to allow for a small further developments, it only practical to use your common sense in accessing further expansion. if the circuit is never going to increase beyond the rated cable value, thats good enough. it is also the responsibity of the person expanding the circuit to ensure the carrying capacities are surficent for the planed expansion.
Also the carrying capacity cables vary because the capacity is determined by not only the cross sectional area of the conductor, but also the insulation ie, mineral insulated is higher rated than PVC.
A simple way to assess the required load is add all the wattages together
double the wattage of any florescent fittings and remember that all the fittings using mains voltage ( ie small spots GU10 etc ) count as total load. Allow 5amps per 1000watts and this will give you some surplus.
Why is it ridiculous?
It was a factual statement. I do not install 1.0mm² cable ever.
1.5mm² is only ~4p a meter more expensive than 1.0mm² (for T&E)
Is it that bad to work beyond the minimum standards laid out in BS7671?
It was a factual statement. I do not install 1.0mm² cable ever.
1.5mm² is only ~4p a meter more expensive than 1.0mm² (for T&E)
Is it that bad to work beyond the minimum standards laid out in BS7671?
I believe it was the "WE" bit that he was referring to..
the fact that YOU don't use 1.0mm², or that I don't use 1.0mm² for lighting circuits is not the issue.. it's that you used the blanket term "WE", which might be taken by the casual observer to mean every electrician on the forum..
the fact that YOU don't use 1.0mm², or that I don't use 1.0mm² for lighting circuits is not the issue.. it's that you used the blanket term "WE", which might be taken by the casual observer to mean every electrician on the forum..
Yeah perhaps a bad use of the 'royal we' in my first reply. (I've altered it now)
RF Lighting said:
Fair point, and each to their own, but there isn't really a huge difference in the current carrying capacity between the two cables either. The main advantage of using 1.0mm² to my mind is that it's quicker and easier to wire with, especially when you have a number of cables coming into a ceiling rose.
I never sujested for one moment that you should never work only to minimum standards and I,m glad to see you don,t however, that was not the question. the question was, ( is it permissable to use 1.0mm T&e for a domestic lighting circuit,) the answer is simply yes.
and good luck to your future customers
and good luck to your future customers
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