Metal pattress in drylined wall?

[Blaggins]

Evening all! Hoping someone can help me.

Whilst decorating upstairs a while back, I changed over our switches and sockets for more decorative ones. This included converting a couple of single sockets to doubles. All of the sockets I changed had plastic dryline boxes in the plasterboard walls. Obviously I replaced like with like and bought double boxes.

We're now doing downstairs, and there's a couple more singles I want to convert.

Annoyingly, the first one I've opened up has a metal pattress/knock-out box in the wall, with the little dry-line tabs in place to make it suitable.
This isn't something I've come across before (in my very limited experience!!) and I'm at a loss for how to change it over. There's a round brass connector coming in the back with one of the cables feeding through, and I can't figure out how to undo it! There's a thread, and a ring with gripped sides which looks like it should undo to disconnect, but I can't budge it.
It also seems to be holding the box in place - I can't pull it out from the wall to get a better look.
Pic:

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• Blaggins
• 24 Apr 2014
• 1

(No idea why the pic is loading rotated 90degrees?!)

Anyone give me any ideas how I can get this thing out to convert to double gang?
Also, any reason why a metal box would have been used, and any problem/risk swapping it out for a plastic dry line box?

I've taken a look at the other socket - that was the plastic box I was expecting, and was swapped out no problem

Thanks in advance!

 

[DaftPunk]

It looks like that socket is part of an old conduit system.

You should be able to unscrew the lock ring from the conduit with a pair of grips but you must replace the back box with a new metal box with the conduit securely screwed back in place. The point fed by the conduit relies on the steelwork to provide its earth so a plastic box would not be suitable.

 

[Blaggins]

Thanks DaftPunk!

Balls. I don't get that - every other switch of socket I've looked at has a plastic box, why's this one different?! Annoying. It is the docket directly below the fuse box, so don't know if that's why?

I couldn't see that the brass ring would budge, & couldn't get the angle on it with a pair of pliers. I'll try again, but might just have to leave this one as a single. Shame. Is there a specific tool you'd use?

Really don't get why there would be one metal box (so far). I'm going to be changing the rest of the sockets/switches, so will see if any others are.

Thanks again.

 

[GaryGarden]

Is there another socket or an FCU on the other side of the stud wall as it looks like the conduit carries a spur, possibly the conduit is holding two back boxes together back to back. Removal of one back box would mean the other having no fixing, dry wall boxes may not fit back to back?

 

[Blaggins]

Is there another socket or an FCU on the other side of the stud wall as it looks like the conduit carries a spur, possibly the conduit is holding two back boxes together back to back. Removal of one back box would mean the other having no fixing, dry wall boxes may not fit back to back?

Hi Gary.

No, there's not another socket. It's on an exterior wall (still cavity/dry lined though). The other downstairs socket i've changed was also on an exterior wall (actually thinking about it, they all are!).

Just remembered the electricity box/meter is on the other side of the wall. feeling round behind the box, the conduit just feels like it's feeding a cable in, but there's no slack at all, so it's clearly connected to something!

 

[Les9000]

I have a socket on an exterior wall which has an identical-looking back box & cables.
In mine, the 2 x T&E are the ring, and the "conduit" one is actually the gland of a SWA taking a un-fused spur to a detached garage.
It was installed when house was built in 1980's.
I would suggest looking for anything outside the house that could be on such a spur.
Les.

 

[Blaggins]

I have a socket on an exterior wall which has an identical-looking back box & cables.
In mine, the 2 x T&E are the ring, and the "conduit" one is actually the gland of a SWA taking a un-fused spur to a detached garage.
It was installed when house was built in 1980's.
I would suggest looking for anything outside the house that could be on such a spur.
Les.

Thanks Les - you may be onto something there. Someone at work just suggested it could be a spur to another socket, but i couldn't think where to - but you may have just solved that.
We do have a detached garage, and there is power to it - a light and a single socket, which i haven't tested. I'll take a look tonight. I think that could be it.

If that's the case, and IF i can get the blasted thing apart, will i need to replace with another metal case and connect in the same manner, so the spur is fused to the metal knock-out box, via the conduit?

Or is there an alternative option using the typical plastic dry-line boxes?

EDIT: What's SWA the TLA for?
EDIT2: nevermind - got it. Steel Wire Armoured cable.

 

[GaryGarden]

Just had a proper look at the image uploaded in the OP and I can not see any CPC (earth) connected to the metal back box which means any conduit running off this box for a spur is unearthed Also if the supply runs underground to an exterior garage the conduit may be introducing a potential. The spur may also be unearthed as there only appear to be two earths twisted together I would expect to see 3.
If no earth is connected then get the earths that are twisted together into a connector and run a fly lead to the back box.
The earth and lives are also dangerously close together and need connecting in terminal blocks to prevent shorting, this will normally only be evident as a fault if you have RCD protection on this circuit. .

 

[Blaggins]

Bingo, this is on the exterior side of the wall!

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• Blaggins
• 26 Apr 2014
• 1

(Again, the daft upload has rotated pic by 90degrees! Must only like landscape orientation?)

Guessing that's a SWA spur to the garage. And it explains why I couldn't pull the box out at all - there's absolutely no give in that cable!

GaryGarden - thanks for the concern & extra detail. Pic was taken after I'd removed the single socket, so all wires were connected before I removed it (& are again now), & there was a length of earth going from the metal box to the 2 twisted together earth cables, & all 3 were (and are now) terminated in the socket earth.

Hope that's all correct??

I'm going to continue changing over the other sockets & switches & will see if I can undo that brass ring over the spur once the rest are done. If so I'll replace with a double metal box and hook up in the same way. If not I'll leave as a single and just change the socket.

Thanks again all for your help. Will post back later.

 

[RF Lighting]

It might be easier to leave the existing flush box in place, and fit a properietory single to twin socket convertor to it.

You need to ensure the SWA gland is properly terminated to the new box if you do replace it as that is how the garage receives it's earth supply.

 

[Blaggins]

It might be easier to leave the existing flush box in place, and fit a properietory single to twin socket convertor to it.

You need to ensure the SWA gland is properly terminated to the new box if you do replace it as that is how the garage receives it's earth supply.

Hadn't thought of that. Can you get flush double converters? Have only seen surface mount ones. I'd rather a flush single than a surface double!

 

[GaryGarden]

It might be easier to leave the existing flush box in place, and fit a properietory single to twin socket convertor to it.

You need to ensure the SWA gland is properly terminated to the new box if you do replace it as that is how the garage receives it's earth supply.

Hadn't thought of that. Can you get flush double converters? Have only seen surface mount ones. I'd rather a flush single than a surface double!

You certainly can the face plate is effectively the same regardless.
http://www.screwfix.com/p/clipsal-converta-socket-1-gang-to-2-gang-polycarbonate/12849
RF's suggestion is best, it's best not to play with the SWA.

 

[sparkwright]

Options;

Use a Converta socket - unlikely to match your other sockets.

Undo the lock ring on the SWA and fit a new double METAL box in the same manner - fiddly for a DIYer.

Leave as a single socket.

Fit a flush double NEXT to the existing single. This is the best way in my opinion, though some minor re-wiring needed, so a short length of 2.5 mm2 twin and earth cable, and some earth sleeving, required.

Whatever you do, that SWA needs to be connected securely to a metal box.

 

[phatboy]

I would fit a new double socket next to that one, and knock a hole in the side of the single box to feed it. On the metal box, fit a double pole 32amp switch, so you can easily isolate the garage electrics in case of a fault with it.

Bit more worth, but no need to remove that box, and you end up with a better solution all in all.

 

[Blaggins]

Thanks so much all, you've been loads of help. Options nicely summarised by sparkwright:

Use a Converta socket - unlikely to match your other sockets.

Agreed - definitely won't match my existing sockets, so this option is out. I thought RF meant a back box converter, rather than a front plate. Something to fit either side of the existing single knock-out box so a double socket could be mounted over. I've seen plastic surface mount ones, but nothing else.

Fit a flush double NEXT to the existing single. This is the best way in my opinion, though some minor re-wiring needed, so a short length of 2.5 mm2 twin and earth cable, and some earth sleeving, required.

This sounds like a bit too much effort. If I really needed more sockets there, I'd consider this. But it's not essential and 3 sockets would be excessive in this particular spot!
Might consider doing this at the tv socket spot tho, rather than running an extension/adapter. Tho I suppose that at least gives me surge protection...

Undo the lock ring on the SWA and fit a new double METAL box in the same manner - fiddly for a DIYer.

Will give this a try tomorrow, and see if I can undo the lock ring. If not...

Leave as a single socket.

I'll do this.

Once again, thanks all for the assistance. Much obliged.

Oh, and fwiw the garage is definitely spurred off the downstairs socket ring. I removed the fuse for the downstairs sockets and the garage electrics stopped working. SWA seems to lead to this:

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• Blaggins
• 26 Apr 2014
• 1

(Again, apologies for orientation. Really annoying this only uploads portrait!)