had a shower fitted is this safe!

[Lectrician]

You need a 10 mm. twin and earth supply to your shower - this must be protected by a 45 mcb possibly a 60. Also fit a RCCD (earth leakage protection) to your consumer unit.

I think you mean 45 or 50!

60? LMAO!

 

[ColJack]

As nobody else has mentioned it i thought i better had. 10mm twin and earth is not rated up to 60amps as suggested by ezekiel, maximum i believe is 53amps so don't ever protect a 10mm twin and earth cable with a protective device any higher than 50amps!

10mm² T+E method 1, clipped direct is 64A.. as long as it's not in insulation and is clipped to the joists / plastered into the wall then it will take 64A..

 

[homespark]

ColJack - you've quoted values for 6mm² clipped direct as 47A and 10mm² clipped direct as 64A. These values are 1A higher than in my 16th edition - where are you getting your figures from? 17th edition? Just curious

 

[Adam_151]

Try table 4D5A instead of 4D2A

 

[homespark]

Thanks Adam, you are a smart cookie but I'm now a bit confused about the difference between (and the need for) those two tables. I've always taken T&E as being 'multicore', hence table 4D2A, but now I see 4D5A mentions 'flat' cable so maybe that's where I should be looking (but it doesn't include ref method 3). Hmmm...

PS Appologies to OP for all this technical diversion

 

[Adam_151]

Table 4D5A was inserted in an ammendment when it was realised that there were no figures which specifially related to flat PVC cable, and so some tests were commisioned. As 4D5A is quite limited and the figures are always higher than 4D2A by a small amount, it would make sense to fall back on 4D2A when data on the method used is not present in 4D5A, afterall, using 4D2A for flat pvc cable is what people did before 4D5A appeared.

 

[homespark]

Nice 'n' clear, as always Adam. Thanks

 

[ColJack]

it's all to do with the spacing and bunching of conductors..

multicore 3 core cable the live and neutral cables are effectively ont seperated by their own insulation, whereas in T+E, they are seperated by the earth..

also, in 3 core round cables, the cores are arranged in a trefoil patern so that each core is in contact with 2 other cores.

it also has less "surface area" exposed to the outside to dissipate heat ( 1/3 of the outside diameter as opposed to half for T+E.. )