Double socket spurred off consumer unit?

[joe384]

Hi, next to my consumer unit I have one double socket that has been there since the house was built.

I assumed this would be on the downstairs ring, but it only has one cable going to it. I've heard that you can have one socket spurred off the consumer unit so I guess it's likely this.

My questions are:

Why not put it on the ring? The socket is right beside the ducting that takes all the cables up into the ceiling so would actually require less cable to put it on the ring.

If I want to add extra sockets, what are my options? I assume I'd have to get a electrician to add this and any additional sockets to the ring? Or replace the socket with a FCU, although that seems a bit silly.

I probably only add a couple more sockets. (maybe more if I can find a neat way to have the some on the other wall)

 

[EFLImpudence]

Hi, next to my consumer unit I have one double socket that has been there since the house was built.

Ok.

I assumed this would be on the downstairs ring, but it only has one cable going to it. I've heard that you can have one socket spurred off the consumer unit so I guess it's likely this.

I guess too.

My questions are:

Why not put it on the ring?

No need; it is fine as it is.

The socket is right beside the ducting that takes all the cables up into the ceiling so would actually require less cable to put it on the ring.

Fair enough.

If I want to add extra sockets, what are my options?

You could put the extra sockets (plus this one) on the ring if you want to add more when the time comes.
Or you could use cable (4mm² T&E) fit for a 32A circuit.

I assume I'd have to get a electrician to add this and any additional sockets to the ring?

Why do you assume that? If you can do it properly, you can do it.

Or replace the socket with a FCU, although that seems a bit silly.

I agree. That is silly.

I probably only add a couple more sockets. (maybe more if I can find a neat way to have the some on the other wall)

Whatever you want.

 

[Murdochcat]

If I want to add extra sockets, what are my options? I assume I'd have to get an electrician to add this and any additional sockets to the ring? Or replace the socket with a FCU, although that seems a bit silly.

Does your CU have any spare slots? Does it have rcd protection?

Adding more sockets to an existing ring may not be sensible

I probably only add a couple more sockets. (maybe more if I can find a neat way to have the some on the other wall)

 

[JohnW2]

Adding more sockets to an existing ring may not be sensible

If one wanted to add more sockets because one wanted to add more loads, then that might be true.

However, if it's just a question of convenience of sockets locations, with no expectation of more/different loads than there have ever been in the past, then I wouldn't really see it as 'not sensible' to add them to an existing circuit. ... or are you suggesting that having a lot of sockets on a circuit is 'not sensible'??

 

[Murdochcat]

Nope. I’m merely pointing out that adding more sockets to an existing circuit may not make sense

There is a big estate near me, built about 40 years ago and a LOT of them only have 1 socket circuit for the whole property. Accumulated Earth leakage is often the cause of rcd trips

 

[EFLImpudence]

Accumulated Earth leakage is often the cause of rcd trips

That's the trouble with RCDs.

 

[JohnW2]

Nope. I’m merely pointing out that adding more sockets to an existing circuit may not make sense

As I wrote, it is adding more loads, not sockets, which may result in problems. The most common situation is that only a small proportion of available sockets is loaded at any one time, and increasing the number of sockets will not normally increase the number of simultaneous loads.

There is a big estate near me, built about 40 years ago and a LOT of them only have 1 socket circuit for the whole property. Accumulated Earth leakage is often the cause of rcd trips

Indeed - that's the potential problem of having a lot of loads on one RCD-protected circuit. However, increasing the number of sockets will not make the problem any worse, provided the user does not suddenly start using more loads simultaneously (which is unlikely)

 

[JohnW2]

That's the trouble with RCDs.

Yes, but there isn't really any way out of it, other than by seriously limiting the number of socket outlets per circuit (say, to just one or two double sockets per circuit).

Even 30 mA can sometimes kill, so if we want devices to provide 'personal protection', a residual current trip threshold above 30 mA would not be acceptable, but just a small handful of 'leaky' loads can add up to that sort of figure.

As I've said before, there have been attempts to devise other methods (not just the magnitude of current) to detect the fact that current was passing through a human body but, as I tried to convince people when I was involved in such research in the past, I think that is quite probably 'wishful thinking (at least, in the way they were trying to do it)', to the extent of probably being a doomed concept!

 

[dal5band]

Don't forget the basics ! A socket in a ring i.e with 2 x 2.5mm cables needs to be protected by a 30amp breaker.
A socket with a single 2.5mm cable needs a 15amp breaker. To extend a ring in the garage would need two cables going into each socket.
With a 15amp breaker you can have a radial circuit with a number of sockets fed by a single cable from the CU , Daisey chain fashion.

 

[pete01]

a ring i.e with 2 x 2.5mm cables needs to be protected by a 30amp breaker.

Or 32 amp

A socket with a single 2.5mm cable needs a 15amp breaker.

Or 16 amp 20 amp or maybe a 25 amp.

With a 15amp breaker you can have a radial circuit with a number of sockets fed by a single cable from the CU , Daisey chain fashion.

Or 16 amp or 20 amp or if 4mm cable 32 amp.

 

[JohnW2]

Don't forget the basics ! A socket in a ring i.e with 2 x 2.5mm cables needs to be protected by a 30amp breaker. A socket with a single 2.5mm cable needs a 15amp breaker. To extend a ring in the garage would need two cables going into each socket. With a 15amp breaker you can have a radial circuit with a number of sockets fed by a single cable from the CU , Daisey chain fashion.

All true, but I wonder what century you're living in?

Once upon a time, we had 30A and 15A fuses, hence 30A rings and 15A radials, but for many decades most people have had 32A and 16A (or 20A, or even 25A) 'breakers' (MCBs or RCBOs) - hence 32A rings and 16 A (or 20A/25A) radials.

Kind Regards, John

 

[Harry Bloomfield]

Why not put it on the ring? The socket is right beside the ducting that takes all the cables up into the ceiling so would actually require less cable to put it on the ring.

It was perhaps added, as an extra, after the ring was installed and completed, therefore easier to just spur it off the CU..

 

[pete01]

Also it might be spurred from the ring via the mcb/rcbo.

 

[Harry Bloomfield]

Don't forget the basics ! A socket in a ring i.e with 2 x 2.5mm cables needs to be protected by a 30amp breaker.

Eh?

A socket with a single 2.5mm cable needs a 15amp breaker.

and again -Eh?

 

[JohnW2]

Also it might be spurred from the ring via the mcb/rcbo.

Is that not what the OP says he is assuming in post #1?