4mm Radial Circuit
- Thread starter nick69
- Start date
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It's very worrying that you've chosen an electrician who doesn't know that - you should give very serious consideration to replacing him with someone actually competent to rewire your house...
H
holmslaw
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Maybe 4mm 32a radials for down stairs, but in a gas CH house do you really need a 32a radial(s) upstairs ?
There's a certain staggered terrace design round here that makes it prudent to provide 2 x radials (front half and back half) of the 1st floor.
Due to ease of load 2 x 20a radials run in 2.5mm works well and keeps inside the 50m sq rules- whole floors run on 1 radial would be outside design due to floor footprint being >50m sq.
There's a certain staggered terrace design round here that makes it prudent to provide 2 x radials (front half and back half) of the 1st floor.
Due to ease of load 2 x 20a radials run in 2.5mm works well and keeps inside the 50m sq rules- whole floors run on 1 radial would be outside design due to floor footprint being >50m sq.
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Even if the cable routes avoid any insulation?
When clipped direct, 4mm carries 37A. Length could be an issue though (~32M max).
You would also have to check that a 1.5mm cpc is sufficiently sized and thermally protected for the duration of a fault.
Don't think 1.5mm CPC is a problem with a 32A MCB, will be even less energy let through with an RCD. We see a 1.5mm CPC on a ring final all the time, on its own in the case of spurs.
iirc the only combination which was cause for concern was the 1mm CPC and 30A rewirable fuse found in some old ring final circuits.
iirc the only combination which was cause for concern was the 1mm CPC and 30A rewirable fuse found in some old ring final circuits.
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holmslaw
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Maybe i should have rephrased that better - method C which uses the same ratings as clipped direct in table 4D5.
H
holmslaw
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Method C is also direct burial in masonry/plaster....
How can you use method C, surely in the majority of house circuits (except garages and sheds etc) the only applicable methods are A or B.
How? Because the majority of installs will be method C.
Have a read of table 4A2, number 58 (page 264 of BS7671:2008)/
It certainly is sir, even with added mechanical protection in the form of capping.
I wonder if Holmslaw is classing capping as trunking?
H
holmslaw
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No problem
H
holmslaw
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