Someone just confirm that I'm right on this please :)

[Hallsy]

Been put on the spot about a job I have been putting off.

7m run of 2.5mm 3 core (P,N+E) fed from 20A MCB on RCD side of house CU, supplying a couple of double metal clad sockets, with a 5A spur for a striplight (1.5mm).

First off, current is OK for 2.5A with swa buried then clipped direct inside shed - right?

Second, allowing for 5m cabling in the shed (prob generous) in 2.5, and say 2m in 1.5 T+E in trunking, volt drop is :

12x20x0.018 = 4.32V
2x5x0.0165 = 0.165V
Total = 4.485V so 1.95% of 230V so OK on volt drop as well.

Just checking that I'm right on above as I've quickly flicked through the regs whilst I had chance, but we've had a new puppy since saturday and time to yourself is something you can forget!!!

 

[Adam_151]

You seem to have the wrong figure for volt drop on the 1.5mm², it should be 0.029 V/m/A

so: 2x5x0.029 = 0.29V

Added to the 4.32v gives 4.61v (2%) so still ok

Other things?

Z's ? (seems ok from a deisgn POV, providing Ze is in spec)
Earthing type?
RCD 30ma and tested?
Part P notifiaction?

 

[Hallsy]

So, I have, that's the trouble with having a quick look, I was obviously looking at one table then reading from another!!

Haven't considered earth loop impedance, although should be OK.

Pretty sure property is PME, will be transporting the earth.

MCB will be from RCD protected side of CU, which is indeed 30mA, not sure when it was last tested. Could try it with an earth/neutral linked plugtop

Part P - it was done in late '04 Or failing that I could just wire the circuit into a plug top and plug it in, perfectly legal then, but ooooh such a bodge, just what Part P is supposed to stop!!

But seriously, joking aside, if the need arises they'll just have to get the property tested. Whether it is done before or after an inspector has asked if something is up to Part P, doesn;t really make much difference

 

[RF Lighting]

MCB will be from RCD protected side of CU, which is indeed 30mA, not sure when it was last tested. Could try it with an earth/neutral linked plugtop

You'll need your stop watch too, to test it like that