16A external Socket

[timtheenchanter]

Hi all, again.

Im putting a 16A Ceeform connector outside for a power supply for my caravan (instead of an adaptor lead through a window)

it will be spurred off the ring, via 2.5mm T&E.
Ive recently had a new C/U fitted, with RCD protection on the sockets.

is there any benefit in adding an RCD connection unit as apposed to a normal FCU? or should i just put on its own 16A MCB on the RCD side of the C/U with an isolator switch?

 

[RF Lighting]

The best thing would be to wire a 16A radial from the CU.

You can supply the socket from the ring via an FCU if you like but this will give you a maximum supply of 13A. (this may be enough for your requirements anyway)

There is no need to install another RCD. Providing there is one RCD somewhere in the circuit, this is sufficient.

 

[timtheenchanter]

the C/U is just about next to where i would tap the ring, so i might as well use a 16A in the C/U. theres a 30mA RCD in the C/U, nice new split load type, with plenty of spare ways,
just need to split the ring into two now

 

[RF Lighting]

just need to split the ring into two now

Why's that then?

 

[Spark123]

What type of supply have you got? iirc PME and caravans don't mix.

 

[timtheenchanter]

to the first, of why split the ring, the ring at the moment is one up, one down for lighting, and a single ring for the sockets, I would prefer for an upstairs ring, and a downstairs. the cables all go up from the same point (just above the C/U) so it will be a simple matter of disconnecting the upstars cables and connect to a seperate MCB.

to the second, no its a TN-S (PME being the one where the earth is connected to the neutral if im correct?)

and yes, you recall correctly, reg; 608-13-05

I wish somone would make the building regs easier to read! not exactly light evening reading!

 

[ricicle]

to the first, of why split the ring, the ring at the moment is one up, one down for lighting, and a single ring for the sockets, I would prefer for an upstairs ring, and a downstairs. the cables all go up from the same point (just above the C/U) so it will be a simple matter of disconnecting the upstars cables and connect to a seperate MCB.


I wish somone would make the building regs easier to read! not exactly light evening reading!

I think you are getting your ring final circuits and radial circuits mixed up.

Lighting circuits are wired as radials.Some socket outlet circuits are wired this way.Most homes have their socket circuits wired as ring final circuits.

You will need to do some thorough testing/inspection before and after to do what appears to be a straightforward job but is almost likely to not be.

 

[JohnD]

What type of supply have you got? iirc PME and caravans don't mix.

I was thinking about putting a 16A radial on the side of the house for caravan or motorthing-owning visitors (on an RCBO, natch).

My installation is PME, would something be wrong with that? Hardstanding is concrete blocks. No spike.

 

[Spark123]

From what I remember the ESQCR says something about not connecting a PME to the metalwork of a caravan or boat.
BS7671 has regs for caravan sites, though wether you'd condider your drive a caravan site is a different matter.

 

[ricicle]

No PME on petrol stations, swimming pools, caravan parks amongst maybe others

 

[timtheenchanter]

cheers, Ill leave it as is then for the moment, finish my course first!

 

[Lectrician]

BS7671 does not permit a PME earth to be connected to the earth pin of the outlet, but does allow it to be used to protect the cable supplying it - IE, split the earthing system at the socket, and incorporate an RCD in the socket.

Reason being, as we all know, on a PME supply, if the supply neutral goes open circuit or high resistance (which happens more often than some may think), the neutral of the installation rises in volts, and could potentially rise to 240v. As the neutral and earth are connected, the earth will also rise in volts.

A caravan chassis/sheets will therefore rise in volts, and as it is fairly well insulated from earth, there could be a 240v difference between the caravan and earth.....

Would you like to walk in or out of that van?

 

[plugwash]

As lectrician says you can't use a PME earth for a caravan, you need to cap off the earth from the cable using a peice of terminal block and run a seperate earth wire from the socket to an earth spike. You MUST test this spike either using a loop tester or an earth rod tester (loop tester is easier)