External socket on ring main

[AndyPRK]

The garage has its own cu with 40a rcd 6a & 32a mcb, so it would only trip the supplies to them and not the house .

While I'm here I also plan on having a spur off one of the double sockets to and fcu , which will then run 10-12 meters of 4.0mm swa cable down the garden to supply a pond pump and possibly a lawnmower , can anybody see any issues with doing that ? And if I put a shed by the pond at some point in the future would there be a way of using this supply for a light and socket own there or would I need to have a new circuit installed ? Thanks

As you have a CU in the garage, you may as well run your new garden supply to it.
If the CU is plastic, run the SWA to a metal single box.

 

[Rossiboy]

As you have a CU in the garage, you may as well run your new garden supply to it.
If the CU is plastic, run the SWA to a metal single box.

I was thinking that but I don't think I have enough swa cable to reach the other side of the garage , and also I would have to run it off a separate mcb right ? And would this not mean I have to uprate the main rcd ? Thanks

 

[JohnW2]

I was thinking that but I don't think I have enough swa cable to reach the other side of the garage , and also I would have to run it off a separate mcb right ? And would this not mean I have to uprate the main rcd ? Thanks

If, as you said, the garden supply is only for a pond pump and occasional use of, say, a lawnmower, then I don't see why you couldn't also run it as a spur from the ring that is going to be in the garage (via a 13A FCU). Provided the 'garden SWA' can get into the garage 'somewhere', you could continue it in ordinary T+E within the garage to get to the CU.

Kind Regards, John

 

[Rossiboy]

If, as you said, the garden supply is only for a pond pump and occasional use of, say, a lawnmower, then I don't see why you couldn't also run it as a spur from the ring that is going to be in the garage (via a 13A FCU). Provided the 'garden SWA' can get into the garage 'somewhere', you could continue it in ordinary T+E within the garage to get to the CU.

Kind Regards, John

Can I spur it of a socket , as there's going to be one right near where I plan on bringing the swa cable , so if I was to spur from that socket with t&e into a fcu then from there in swa down the garden , is this acceptable ?
Thanks

 

[JohnW2]

Can I spur it of a socket , as there's going to be one right near where I plan on bringing the swa cable , so if I was to spur from that socket with t&e into a fcu then from there in swa down the garden , is this acceptable ?

That all sounds fine to me - provided only that the socket you spur from is part of the ring, and not itself already a spur.

Kind Regards, John

 

[Rossiboy]

That all sounds fine to me - provided only that the socket you spur from is part of the ring, and not itself already a spur.

Kind Regards, John

Okay I will do that then , with regards to the external socket again , is there a reason why you would use the double pole switch and not the fcu ? Would the double pole stop the whole ring tripping if the external socket got wet ?

 

[JohnW2]

Okay I will do that then , with regards to the external socket again , is there a reason why you would use the double pole switch and not the fcu ? Would the double pole stop the whole ring tripping if the external socket got wet ?

Even an FCU would not stop the whole ring (indeed, the who garage supply) being tripped if the external socket got wet. However, if such a trip did occur, either a DP switch or an FCU (which also includes a DP switch) would allow you to isolate the external socket and therefore be able to reset the garage CU's RCD (which would otherwise be impossible unless/until you disconnected or 'dried out' the external socket). As has been said, the fuse in the FCU would not really achieve anything.

I realise that you might be concerned that a trip due to water in the external socket could kill the supply to your freezer but, so long as they are supplied from the same CU (hence the same RCD), that risk is unavoidable, and would still be even if you put an FCU in the feed to the external socket.

Kind Regards, John

 

[AndyPRK]

I was thinking that but I don't think I have enough swa cable to reach the other side of the garage , and also I would have to run it off a separate mcb right ? And would this not mean I have to uprate the main rcd ? Thanks

You wouldn't have to update the main RCD, no.
Yes a spare MCB way maybe an issue?

You could run T&E though the garage. It would be worth while if you plan to connect it to a shed and all sorts in the future.

 

[Rossiboy]

Ok then thanks for everyone's help , much appreciated