I'm going to be rewiring my house and am considering using 1mm cable for the lighting circuits. Is there any particular reason why 1.5mm is used so commonly? It'll be on 6A MCBs and star-wired. I've heard that 1.5mm can be easier to work with, but I'd have thought the reverse would be true.
Why 1.5mm cable for lighting?
- Thread starter RossR
- Start date
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TLC (100m *1.5mm) £30 plus £4.99 delivery plus VAT = £41.98
TLC (100m *1 mm) £25 plus £4.99 delivery plus VAT = £35.98
Get the calculator out
No they don't its just around the corner
The original question was whether to use 1.5mm or 1mm cable - my response was one is cheaper than the other - nuff said.
What if TLC is just round the corner?
1mm T&E will happily carry 8A in the worst case scenario (ref method 103), and 16A at best (Ref Method C) so is more than adequate for a 6A lighting circuit
I far prefer 1.0mmsq, although previous discussions in a similar vein suggest that a lot of other DIYnot'ers prefer 1.5mm. My dislike of the larger conductor size is that many modern fittings provide very little space for cable termination, making the smaller conductors much easier to form and work with.
If you are using 6A CPD then 1mm² is fine for a lighting circuit
providing that - when you do the cable calculations (you will be doing cable calculations??):
the vd is within limits
the EFLI is OK
and (of course)
that the load is not more than 6amps!
[/u]
providing that - when you do the cable calculations (you will be doing cable calculations??):
the vd is within limits
the EFLI is OK
and (of course)
that the load is not more than 6amps!
[/u]
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In the main we are lazy. 44 mV/A/m to 29 mV/A/m means the amount of 1mm which we can use and stay within the 3% volt drop is a lot less than with 1.5mm. OK at around 40 meters it will take a lot of cable before we run into a problem but to without calculating use 1 mm means at end of day it may fail but with 60 meters allowed with 1.5mm one is very unlikely to have a problem.
I don't anticipate volt drop being an issue as it will be star wired, so won't be taking a meandering route round the building, and in normal operation the current in each leg will be a small fraction of 6A. There will of course be a run of cable from the MCB to where the circuit branches off to the individual lighting points, which will have the full current.
Likewise, Zs shouldn't be too high.
Likewise, Zs shouldn't be too high.
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