Twin and Earth
- Thread starter mbrooke
- Start date
If clipped to surface or buried in masonry:What is the current carrying capacity of 1.5, 2.5, 4, 6 and 10mm2 Twin and earth for normal domestic applications? Sorry for the basic question.
20, 27, 37, 47, & 64 Amps respectively: 1mm² is 16A.
In conduit and thermal insulation a lot less.
If clipped to surface or buried in masonry:What is the current carrying capacity of 1.5, 2.5, 4, 6 and 10mm2 Twin and earth for normal domestic applications? Sorry for the basic question.
20, 27, 37, 47, & 64 Amps respectively: 1mm² is 16A.
In conduit and thermal insulation a lot less.
Thanks!
What are the de-rated values? My understanding is that 1.5mm2 is usually restricted to 16amps and 2.5mm2 to 20amps. Unsure about the others.
De-rating is necessary only if installation factors such as EFLI mentioned are operative - e.g. installed in conduit, within thermal insulation, when cables are 'grouped' together etc. In the absence of any such factors (e.g. if surface mounted or buried in paster etc.), cables may be used up to the currents that EFLI specified, without any de-rating.
Kind Regards, John
The values that you have quoted are the (rule of thumb) fuse values to protect those cable sizes. Any cable installation should be subjected to a proper cable sizing calculation that will take into account many factors.
A guide can be found HERE . You'll need a copy of BS7671 to get details of reference methods, ambient temperature effects, etc etc.
Indeed - although, under 'ideal' installation conditions, 1.5mm² cable can be protected by a 20A fuse/MCB, and 2.5mm² cable by a 25A MCB (if one can find one for one's CU!).
Kind Regards, John
On what pages or sections of BS7671 would I be looking at?
This is in a wall btw normal ambient temperature (not over 30*C).
If you told us exactly what you're trying to achieve, we could probably be of more help - rather than our just trying to answer general questions.
Kind Regards, John
Page 364, Table 4D5, Method C.
... assuming that the OP is looking at the latest (yellow) Amendment of BS7671. In the previous (green) one, Table 4D5 was on page 340.
Whether or not Method C is applicable obviously depends on exactly what the OP means by "in a wall".
Kind Regards, John
Then he will notice the other methods.
Hopefully he would. I still think it would have been easier, both for the OP and us, if he had told us exactly what he's doing and what he wants/needs to know!
Kind Regards, John
http://www.amazon.co.uk/IET-Wiring-...F8&qid=1430060088&sr=1-1&keywords=bs7671+2008
It is not available free on line (I wish)
It is not available free on line (I wish)
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