EICR

[Fleeting]

I suppose we will, eventually, in the UK realise the folly of still using T&E and cpc's of a different size to the phase and neutral and embrace the rest of the modern world.

Why is it a folly.

 

[MikeJhn]

Making life difficult is folly.

 

[Fleeting]

Making our own life difficult is folly.

Why does a differing csa cpc make things difficult.

 

[champagnecharly]

Making our own life difficult is folly.

But surely a cpc of the same SA as the line and neutral would be a waste of copper wouldn't it?
Extra cost of cable V a simple calc.

 

[Goldstar]

EICReports can vary considerably as each sparky has diff standards but also most agents pay peanuts so it's a very quick nip round with lots of limitations marked on the form basically it keeps agent happy as he has a form to tick a box also landlord not normally aware that agent tales 10-15% out of sparkies price on the quite.

 

[MikeJhn]

Why does a differing csa cpc make things difficult.

For the same reason that FRC are out of date, and you know exactly what I meant, just being obtuse.

 

[Fleeting]

For the same reason that FRC are out of date, and you know exactly what I meant, just being obtuse.

Nope not with you.

 

[Richard-the-Ninth]

Just a polite note. Keep it friendly (as you are) and sometimes one person can not see the wood for the trees.

 

[mort2376]

Why should the cpc be the same size ?

The current flow through it under fault conditions is large, but also for a very short duration.

Most of the time it's a piece of cable that just sits there waiting for something to happen.

 

[binky]

All CPCs are sized for the maximum current flow for the size of cable under dead short conditions. Max current is limited by the OCPD, and if I remember correctly 2.5/1mm was deemed possible to fail because we tend to use it as a ring hence it was increased to 1.5mm. I'm trying to remember the exact details of that, but it's a long time since I read anything about it. I'll try a Google search later.

 

[Fleeting]

I believe the 1.0 cpc was upgraded due to possible failure when protection was afforded by a BS3036, 30A semi enclosed fuse.

 

[binky]

I believe the 1.0 cpc was upgraded due to possible failure when protection was afforded by a BS3036, 30A semi enclosed fuse.

that's the one!

 

[Phoenix]

Yeah I think the adibatic comes out at about 1.15mm² In reality it won't fail as such (only fail to meet the requirements), just that the copper in your 70Deg PVC sheath might exceed the 160 degree its allowed to reach by the end of the fault, of course we are assuming its running at 70Deg to start with. But assuming the cable is at 70 to start with, and all the current goes down the single 1mm cpc (fault on a spur, or the cpc of ring is open, or its very close to one end) then it might reach 200degish at the end of 0.4s and maybe damaged the pvc slightly. Its not quite complete instant failure of the cable!

And of course touch voltage is higher than on 2.5/1.5 but BS7671 doesn't worry about that as long as we keep the duration less than 0.4s, we wouldn't have 4/1.5 otherwise.... always best to try and keep it as low as possible though