Planning for an external socket

[diy_dude]

I am planning to install an external socket when I do some re-wiring work. I will apply to LABC re: part P.

I have a split load CU with 4 RCD ways, 1 used for all sockets and 3 free. It also has 6 non-RCD ways, non currently free. There is a ring for sockets upstairs with the 3!! double sockets downstairs spurred from it. The kitchen has its own radial circuit.

I initially planned to install a new ring for the downstairs through lounge and hall (7 double outlets) and replace the radial in the kitchen. I was going to connect both of these circuits to the RCD side of the CU leaving just one spare way. The shower is currently connected to the non-RCD side of the CU so I was going to move it into the last free RCD way. The non-RCD side would have a free way after I had moved the shower and kitchen socket circuits and added a new radial for the oven.

Now we have decided an external socket would be very useful for occasional use, lawn mover, etc.. However I am now stuck as to where to connect it to as I know it needs RCD protection.

Could I include it into the downstairs ring when I install it? Or should I try to keep a RCD way on the CU free to dedicate to this outlet?

 

[JohnD]

It will be simplest to take it off the (RCD protected) downstairs ring.

You will continue to have the problems with split-load boards, that a fault on one circuit will take out whatever else is on the RCD; and that minor leakages on several circuits can add up and lead to nuisance tripping.

It would be possible to use a dedicated radial with an RCD-protected weatherproof socket, but this would be considerably more cost and work. It might be worthwhile if you are thinking of later extending the outdoor supply for a shed or other outbuilding, or fishpond.

BTW, what make is your CU, and do you know about RCBOs?

 

[diy_dude]

Thanks for the advice. That is more or less what I was thinking.

My CU is a Square D Domae box.
What it an RCBO please?

Just a thought abour RCB's then. Should the kitchen rimg be conected to the RCB side of the board? I dont want the contents of my freezer to melt if the breaker trips......

Thanks again

 

[JohnD]

M'mmmm.

An RCBO is a single device that contains an MCB and an RCD, it protects a single circuit (like an MCB). Depending on brand, it may be the same width as an MCB, or twice as wide. They fit into the same consumer Unit like an MCB, although I don't know the Square D range. They give the enormous benefit that you can provide protection to e.g. your pond pump, but will not lose power to other circuits if it trips. Of course, it is more expensive to have (say) four RCBOs than a single RCD protecting four circuits together.

Ideally, you would have your freezer on a non-RCD radial circuit (and possibly the Microwave too, as they are prone to nuisance tripping). Not everyone is lucky enough to have one.

In my opinion, the kitchen sockets ought to be on an RCD, to cope with the kettle/tap/wet hands scenario, the steam iron/frayed flex/leaky water tank one, or the washing machine/cracked hose/wet terminals one.