Switched fused socket

[Diynotnewb]

Hi, please can anyone help.
When my conservatory was built the electrician said he fitted a switched fuse so i can turn the electric off in there.

I have a ceiling light fan that has its own light switch then i have the switched fused socket and then 3 other sockets for my tv etc.

When i flick the switched fused socket off the light wont work anyone but all of my sockets still work (my tv) is this correct? Did i misunderstand what he meant and the sockets would not be isolated just the light?

 

[EFLImpudence]

It would appear so.

The switched fuse was probably fitted because the light and fan require a lower fuse than the sockets.

It's not a question of right or wrong.

 

[securespark]

Hang on. You said you have a light switch and three sockets and a switched fused socket. What do you mean by this?

What I'm getting at is that I have seen a spur fed into a conservatory before where the feed to the conservatory was fused down by a 13A fuse, then fed onto some sockets and another switched fuse spur for the lighting at 3A.

So the whole lot will turn off if you switch off the 13A spur.

 

[JohnW2]

Hang on. You said you have a light switch and three sockets and a switched fused socket. What do you mean by this? What I'm getting at is that I have seen a spur fed into a conservatory before where the feed to the conservatory was fused down by a 13A fuse, then fed onto some sockets and another switched fuse spur for the lighting at 3A. So the whole lot will turn off if you switch off the 13A spur.

As I understand it, that's almost what the OP thought he had (although he didn't mention a second FCU for the light). However, from what he has described, it appears that just the conservatory light/fan is fed from the SFCU - at least, the FCU he has 'found'.

However, as I think you are probably implying, I wonder if the OP has 'missed' a second switched fuse unit, which supplies everything in the conservatory (sockets+lighting).

Kind Regards, John.

 

[Diynotnewb]

Hi cheers for the replies

I dont appear to have any other fcu for the conservatory.

The fcu i can see and switch off does have a 3 amp fuse in it. It looks like the socket right next to this fcu is connected to it as i can see the wires behind and the other two sockets are across the room also have 2 set of wire going to the back of them.

Not being too sure about electrics I just thought because the sockets were linked to the fcu it meant it would isolate the power to everything. Im sure thats what he told me.

I dont really understand why he would fit a switch for the fan light only.

Sorry the silly questions but

Please can anyone explain did I need the switched fcu,
If yes and it is only to turn the light fan off why are the sockets linked to the fcu?
Should the sockets of had their own fcu?

When going away I turn off all my electrics and liked the thought that I was completely cutting the power in the conservatory via the fcu ( not sure why i do this possibly a woman thing) but it appears all this time all i was doing was turning the light off

 

[rjm2k]

He's probably taken the light feed from the same socket circuit as the sockets themselves, as a diy'er I can think of a number of reasons he may have added the FCU for the lights...

The light doesn't need to be able to draw 32 Amps so by fusing down, if a LN short occurs it will blow the FCU fuse before taking the rest of the sockets down

In a conservatory, the roof may leak, by providing a presumably Double Pole FCU you can disable the light and prevent RCD trips until it's dried out

He may have run smaller cable upto the light so fusing down protects it

You are much more likely to need to change a lightbulb than a socket, so you can safely isolate (particularly given that it's a metal fitting I assume).

I wouldn't worry, never assume a circuit is dead because you flipped a switch that you believe controlled it!

Do you think the additional sockets are on a ring, or spurred off one? You can "guess" by the number of cables in and out, but really testing is the only way to tell. What did his paperwork say?

 

[PrenticeBoyofDerry]

As others have mentioned, there are number of possibilities here.
*Socket circuit extended from existing circuit in the house and 3 FCU for isolating light only.
*There could be another 13 FCU, this would be I expect to be in the main house near a socket outlet.

It is sensible to have the extension of the socket circuit to be down fused for lights.

Now this could introduce a whole new can of worms to the thread.
If the circuit does not have a 13A FCU, for the additional sockets and has been spurred from a ring final circuit, then under guidance of BS7671 it would not conform.
When was this work done? Do you have documentation from the installer? Is RCD protection offered to buried cable (less than 50mm within wall, that is not mechanically protected)? and are the sockets protected by a RCD?

 

[Diynotnewb]

Hi, just found the works certificate. Work done 2006

It doesn't say alot.

Works carried out: ext to ring main
Method of protection against indirect contact: eebdds
Protective device for the modified circuit: fuse rating 30a. ( what is this? Daft Q. Bt the fuse in the fcu is 3 amp)
No other fcu fitted at that time

All this time i though nothing of it. And now noticing it just wanted to make sure this set up is pk and it is wired up correctly. Its just the way he said i could cut the power in the conservatory.

The reason that i have just asked these questions is because I was going to get an outside socket fitted (us doing the prep work and the professional to do the final wire) we got some basic advise from then local diy shop and
because i thought we had a switch to cut off the electric to the sockets we were going to wire the outside RCD protected socket direct to the socket in the conservatory (i wanted to be able to cut the power outside from inside when not in use) until i noticed i could not cut the power to my sockets i then thought best to check as the wiring is not as i first thought.
So now thinking i will need to wire the outside socket up similar to an extension with a normal plug on the end that i just unplug from inside when not in use ( thinking ok to do this as the outside socket itself is rcd protected rather than having another rcd plug on the inside)
I did think we had it all sorted and it seemed straight forward but now im thinking i was kidding myself to think we could do this

 

[PrenticeBoyofDerry]

With out seeing the installation and not knowing whether it is a radial or ring final, it would be difficult to say whether the installation has been done correctly.
But it seems by the limited information given to us from the certificate and your comments, that you have had a 30A socket circuit extend, (this could be ring or radial, it makes a difference when altering or extending, which type of circuit it is).
And a 3A FCU has been used to down fuse for light.

If you want to install an outside socket, this is still possible and a separate means of isolation can be introduced internally for this socket, in fact it is a wise option to have a two pole isolator.
The date of the work is pre-requirement of RCD protection of buried cables and sockets, but the new external socket must have this, as will any new buried cables that are not mechanically protected and less than 50mm within walls.

 

[JohnW2]

Hi, just found the works certificate. Work done 2006 It doesn't say alot.
Works carried out: ext to ring main
Method of protection against indirect contact: eebdds
Protective device for the modified circuit: fuse rating 30a. ( what is this? Daft Q. Bt the fuse in the fcu is 3 amp)
No other fcu fitted at that time

OK. It sounds as if he probably extended the house's ring circuit to include the conservatory (i.e. made the conservatory sockets part of the ring), with the 3A spur taken off it for the light/fan - in which case everything is probably fine. Having been done in 2006, prior to introduction of the current edition of the Wiring Regulations, the requirement for RCD protenection mentioned by PBoD would not have applied. The 30A protective device presumably refers to a 30A fuse in your fuse box which is protecting all of the ring.

Its just the way he said i could cut the power in the conservatory.

If he did incorporate the conservatory into the existing ring, there would be no (sensible) way to cut the power just to the conservatory, so I wonder of you somehow misunderstood what he said.

The reason that i have just asked these questions is because I was going to get an outside socket fitted (us doing the prep work and the professional to do the final wire) we got some basic advise from then local diy shop and because i thought we had a switch to cut off the electric to the sockets we were going to wire the outside RCD protected socket direct to the socket in the conservatory (i wanted to be able to cut the power outside from inside when not in use) until i noticed i could not cut the power to my sockets i then thought best to check as the wiring is not as i first thought.

You really need to involve an electrician now, since it is crucial to first confirm (by testing) that the sockets in the conservatory really are part of a ring. If they are, then a switched FCU could be connected to one of the sockets to supply power to the outside socket (thereby giving you an internal means of disabling the outside socket). If the electrician were to find that the conservatory sockets were not part of a ring, then you would have a more general problem that needed addressing, which you could discuss with the electrician - but hopefully that will not be the case.

Kind Regards, John

 

[JohnW2]

But it seems by the limited information given to us from the certificate and your comments, that you have had a 30A socket circuit extend, (this could be ring or radial, it makes a difference when altering or extending, which type of circuit it is).

Works carried out: ext to ring main

It therefore clearly was a ring final circuit which was 'extended' - so, as I've just written, particularly in the absence of any reference to a spur or FCU, I think this probably really does mean that the ring was extended. However, as I've told the OP, he really needs to get an electrician to confirm this before it can be decided how to proceed.

The date of the work is pre-requirement of RCD protection of buried cables and sockets, but the new external socket must have this, as will any new buried cables that are not mechanically protected and less than 50mm within walls.

That's all theoretically true. Assuming it is a ring, the OP could feed his outside socket via an RCD FCU very close to one of the sockets, in which case some people might be prepared to overlook the 'couple of inches' of new cable that was not RCD protected. He could then obvioulsy just have an 'ordinary' (not RCD) socket outside.

Kind Regards, John

 

[Diynotnewb]

Thank you very much its making sense to me now.sort of.

I misunderstood him then.

With regard to my outside socket, this originally seemed like an ok basic/ish job.
When i googled it and spoke to my local shop the idea was to buy a socket that had the rcd plug already attached to it so just drilling a hole in the wall and plugging it in is what most were doing.
But i was given for free a socket with rcd protection the type with no plug attached. After speaking to others they said it would ok to just wire it up like an extension with a normal plug instead of an rcd plug.

That way sounded good and simple, the outside socket will be used for outside lights and lawnmower.

From what you have said about fitting a two pole isolator or a switched fcu for my socket is now sounding more in depth than i first thought.

Is what the others advised about putting a plug on the end not advisable or dangerous in this case?

 

[rjm2k]

It would be "better" to not have a flex going to your outdoor socket with a plug on the end, post a photo of what you were given but it seems you need a sparky on site.

 

[Diynotnewb]

Picture of my socket.
Shame its not going to be simple, what if i had bought on the sockets with the flex and rcd plug already attached would this be any easier to fit i.e drill hole through wall and plug it in

Untitled

• Diynotnewb
• 12 Aug 2013
• 1

 

[JohnW2]

That way sounded good and simple, the outside socket will be used for outside lights and lawnmower. ... From what you have said about fitting a two pole isolator or a switched fcu for my socket is now sounding more in depth than i first thought.

Perhaps, but an almost trivial job for an electrician.

Is what the others advised about putting a plug on the end not advisable or dangerous in this case?

Having a plug on the end certainly isn't very nice, although it would be quite hard to find a reason for caling it dangerous. I would add that having outdoor lighting plugged into an outdoor socket is not very 'nice', either - it would be far better to have it properly 'wired in' (probably from the oudoor socket). One thing to be said for involving an electrician is that (s)he could check and (hopefully) confirm that your conservatory sockets are part of a ring. If, by any chance, they are not, then that probably ought to be investigated and addressed, regardless of the matter of the outside socket.

Kind Regards, John