Existing kitchen socket set up VS proposed new set up (diagrams included)

[Whynot123]

Hi all,

I know an electrician will be needed for what I propose but I always like to get a few opinions before I go ahead. It's nice to be equipped with some knowledge, so thanks in advance for any advice. It really is appreciated.

We're having a new carpet laid in the bedroom above the kitchen and whilst the floorboards are exposed it's a great time to sort some kitchen sockets and switches directly below the room.

The two diagrams below show the existing kitchen socket set up on one of the walls and then a proposed set up that I'd like.

Existing layout

There are two double sockets (shown below in the diagram). The one on the right is on the ring main.

The house is only a 2 bed semi and all sockets are on a single ring main, RCD protected with a 32amp MCB (no separate socket circuit for each floor or for the kitchen, etc).

The left double socket is on a radial circuit going directly to the consumer unit into the same MCB as the ring main (so it has 3 cables). It's the only socket in the house that is outside of the ring main on it's own radial circuit. This radial circuit has a thicker 6mm cable and I'm assuming it was originally for a cooker before we moved in (although that's no longer the case).

Proposed layout

I'd like to change this wall by adding a 20amp DP switch above the counter next to the sockets. This switch will feed an unswitched single socket to power a dishwasher. Ideally, whilst we're there I'd like the left hand socket added into the ring main so we can do away with the radial attached to the same MCB. So it will look like this:

What do you guys think about this set up?

Thanks

 

[winston1]

I would have thought that was perfectly OK but I was told in this thread that feeding a 20A DP isolator from a ring final is not compliant. See what others say.

//www.diynot.com/diy/threads/feed-to-shed.456093/page-2

 

[EFLImpudence]

Yes, it's fine. Do you not want more sockets than that?

 

[Whynot123]

Thanks winston1, ah I see and I've read about this. In that case is the alternative to use a SFCU instead of the 20A DP? And use a flex outlet instead of the socket to avoid having 2 fuses? Or use 20A DP switches in a grid with a fuse module that complies with BS1363.

I was hoping there was a standard practice way of doing this but I guess it's one of those things that people disagree on or interpret the regs differently?

Well, I have 2 people give the go ahead so far. Thanks EFLImpudence aswell, yes there are more sockets in the kitchen on the other walls and they are part of the ring main too.

 

[EFLImpudence]

No, just use the switch. There's nothing wrong with doing so.

 

[securespark]

You could use the 6 milli to run a radial circuit to some power hungry appliances in the kitchen, taking the load off the ring final.

 

[Whynot123]

You could use the 6 milli to run a radial circuit to some power hungry appliances in the kitchen, taking the load off the ring final.

Yes that's a good option, these power hungry appliances would be plugged in below the worktop so I would need isolation switches above the worktop. Do you agree with the winston1 and EFLImpudence that it's OK to use the 20A DP switches? Or this may change things now because it's a radial and not a ring?

 

[securespark]

Can't see an issue. The switches are still switching the same loads.

 

[Whynot123]

It sounds like I'll go down this route assuming the electrician I hire agrees too. But out of interest, would a 32amp DP switch solve the debate entirely? They are available but not in the range of switches that I'm using. So how about using a 45a DP switch instead of the 20amp DP? As the ring main is protected with the 32amp MCB and then the socket will have a plug with a 13amp fuse in it, would a 45amp DP switch be better than the 20?

 

[EFLImpudence]

But out of interest, would a 32amp DP switch solve the debate entirely?

No, they are not BS1363 either, but that reason for not using 20A ones is not valid.

They are available but not in the range of switches that I'm using. So how about using a 45a DP switch instead of the 20amp DP?

They are very clunky.

As the ring main is protected with the 32amp MCB and then the socket will have a plug with a 13amp fuse in it, would a 45amp DP switch be better than the 20?

No, for the reason above and they don't look the same.
20A switches on a ring circuit is fine because there are two wires sharing the loads.

An isolation switch is not required by the regulations.
It is a personal choice and a good idea but not mandatory.

Having a 20A switch on a 32A radial circuit does raise more valid reasons although there could be ways round it.

 

[JohnW2]

There are two double sockets (shown below in the diagram). The one on the right is on the ring main. .... The house is only a 2 bed semi and all sockets are on a single ring main, RCD protected with a 32amp MCB (no separate socket circuit for each floor or for the kitchen, etc). The left double socket is on a radial circuit going directly to the consumer unit into the same MCB as the ring main (so it has 3 cables). It's the only socket in the house that is outside of the ring main on it's own radial circuit.

Since no-one else seems to have mentioned itr so fdar ... technically speaking that left socket is not on a radial circuit of its own - but, in fact, is an unfused spur from the ring circuit. Spurs are allowed to originate anywhere in a ring circuit - most commonly from a socket on the ring, sometimes at a junction box or, albeit not very common, from the origin of the ring circuit (i.e at the ring circuit's MCB - as in your case.

This radial circuit has a thicker 6mm cable and I'm assuming it was originally for a cooker before we moved in (although that's no longer the case).

That's a bit odd, and if that cable ever 'needed' to be 6mm², it is very unlikley that it would have been appropriate for it to be wired as a spur from a 32A ring circuit!

Kind Regards, John

 

[Whynot123]

There are two double sockets (shown below in the diagram). The one on the right is on the ring main. .... The house is only a 2 bed semi and all sockets are on a single ring main, RCD protected with a 32amp MCB (no separate socket circuit for each floor or for the kitchen, etc). The left double socket is on a radial circuit going directly to the consumer unit into the same MCB as the ring main (so it has 3 cables). It's the only socket in the house that is outside of the ring main on it's own radial circuit.

Since no-one else seems to have mentioned itr so fdar ... technically speaking that left socket is not on a radial circuit of its own - but, in fact, is an unfused spur from the ring circuit. Spurs are allowed to originate anywhere in a ring circuit - most commonly from a socket on the ring, sometimes at a junction box or, albeit not very common, from the origin of the ring circuit (i.e at the ring circuit's MCB - as in your case.

This radial circuit has a thicker 6mm cable and I'm assuming it was originally for a cooker before we moved in (although that's no longer the case).

That's a bit odd, and if that cable ever 'needed' to be 6mm², it is very unlikley that it would have been appropriate for it to be wired as a spur from a 32A ring circuit!

Kind Regards, John

Thanks for explaining that John. That does make sense. I'm not sure why or when it was added as a spur. I'm tempted to say it was like it was when the house was built in 1982 because the cabling and installation looks like all the rest. Unless it was originally a separate circuit for an oven and it has been changed to a double socket in the kitchen and then added to the socket MCB as a spur when the consumer unit was upgraded (2013). Something must have been changed somewhere along the line.

As it's so near the sockets of the ring main it will be easy to move this socket into the ring and do away with the radial.

 

[securespark]

That's a bit odd, and if that cable ever 'needed' to be 6mm², it is very unlikley that it would have been appropriate for it to be wired as a spur from a 32A ring circuit!

I suspect, and maybe you do too, that it was a cooker supply that has been moved over to the ring final circuit.

 

[JohnW2]

That's a bit odd, and if that cable ever 'needed' to be 6mm², it is very unlikley that it would have been appropriate for it to be wired as a spur from a 32A ring circuit!

I suspect, and maybe you do too, that it was a cooker supply that has been moved over to the ring final circuit.

Yes, that would be a possible explanation - but if there was (and still is) an MCB for a cooker circuit in the CU, then I'm not sure what would have been gained by moving it - unless, of course, there was a need to 'find a spare way' in the board.

Kind Regards, John

 

[ban-all-sheds]

Bear in mind that there are countless examples of things done which make no sense because they were done by people who didn't know what they were doing.