How do I plaster behind double socket?

[Ambergreen45]

But rather awkward to remove the existing flush box from the conduit.

I've just removed all loose plaster around the old flush box and it would be very difficult indeed to remove it since it is retained by three metal conduits (two unused). These are embedded not just in plaster but also into part of the brickwork.

I've also noticed two big drilled holes just by the surface of the used metal conduit and the person who did that must have taken big chances not realising it was there; the drill bits must have been in contact with it when the drilling was done! Fortunately the used conduit is still sound.

One of the single-to-double 'converter' sockets might be neater, and not need a new box, and work with the length of cable that's available.

What is a single-to-double converter socket?

Another question I would like to ask. Still working in the same spot but immediately on the other side of the outside wall I've unscrewed an external junction box and noticed the cables of the armoured cable were thinner than 2.5mm, probably 1.5mm. That black armoured underground cable leads to my old garage about 40 metres away where I have a light and a 2 gang socket. I rarely use electricity in the garage. For that purpose, which fuse shall I put in the new FCU that will be next to the 2 gang socket in the house?

Which would be the best fuse to use?

 

[PrenticeBoyofDerry]

If you google "single to double convertion box" plenty to be found

 

[PrenticeBoyofDerry]

Another question I would like to ask. Still working in the same spot but immediately on the other side of the outside wall I've unscrewed an external junction box and noticed the cables of the armoured cable were thinner than 2.5mm, probably 1.5mm. That black armoured underground cable leads to my old garage about 40 metres away where I have a light and a 2 gang socket. I rarely use electricity in the garage. For that purpose, which fuse shall I put in the new FCU that will be next to the 2 gang socket in the house?

Which would be the best fuse to use?

The cable is way under rated for socket/lights and voltage drop at that distance. Would require updating to larger CSA.
Even restricting the circuit to a 13A FCU, would not calculate in your favour.

 

[Ambergreen45]

The cable is way under rated for socket/lights and voltage drop at that distance. Would require updating to larger CSA.
Even restricting the circuit to a 13A FCU, would not calculate in your favour.

I only use the light in the garage. Not that I would, but just out of interest, what could happen if I were plug a 500W power drill in the socket in the garage under the current situation, or could a problem occur at higher Watts?

 

[ban-all-sheds]

I've just removed all loose plaster around the old flush box and it would be very difficult indeed to remove it since it is retained by three metal conduits (two unused).

Have you tried undoing the nuts?

 

[sparkwright]

As the garage supply is existing, and you only need the light, I suppose fit a 13 amp fuse at the house end and a 5 amp fuse for the lighting in the garage. I imagine, but can't be at all certain, there is a fused spur unit in the garage for the lighting. If not, fit one. Somehow use the socket only for occasional use until you can upgrade the supply cable. That's a job for another day.

It may be that the metal conduit is imperial size, so fitting a new flush double metal box may be a bit difficult, as you would have to drill your own 1/2 inch hole into the back box. This can be awkward as the 20 mm knockouts could get pushed out, which makes a bad joint when tightening the locknut.

It's odd that there are three conduits and two are unused - suggests an alteration has taken place.

 

[Ambergreen45]

Have you tried undoing the nuts?

The only thing that looked a bit like nuts is a plastic bit at the end of each conduit, as soon as they enter the box (probably a gomet). The box is also secured by mortar surrounding it. Somehow I could not see any proper nuts; but there are threads in each corner of the box to fit a screw. It looks like originally there was only one socket per room and these must have been converted to surface mounted ones in addition to fitting more sockets per room when that work was done.

I imagine, but can't be at all certain, there is a fused spur unit in the garage for the lighting.

Yes, there is a grey one in the garage from where a new cable starts from the 2 gang grey socket to the light above.

It's odd that there are three conduits and two are unused - suggests an alteration has taken place.

The 1st picture below shows both conduits were I have removed the skirting board. I took those pictures before commencing work as it would have been difficult to see what's in the metal box as the cables and choc box come out of it. I have drawned hatches on the one that has the cables in it which passes behind both FCUs. The conduit just below the socket ends at the bottom of the metal back box but starts again at the top of the box. The 2nd picture (which I sent on one of my thread before) shows the conduit starting again from the top of the metal back box, but now I know there are no cables inside that tall conduit (and the one below coming out of the screed). But I have no idea what was the purpose of it, I just discovered it when taking the plaster off the outside wall.

Untitled

• Ambergreen45
• 20 Jul 2013
• 1

Electrical 1-3

• Ambergreen45
• 8 Dec 2012
• 2

Electrical 1-3

 

[ban-all-sheds]

So the only cables there come from the RH bit of conduit which comes up from the floor?

How many cables?

How are the 2 FCUs and the socket wired?

What is connected to the load side of the 2 FCUs?

 

[Ambergreen45]

So the only cables there come from the RH bit of conduit which comes up from the floor?

Yes it does.

How many cables?

Mains cables from the RH conduit to the socket: 2 x 2.5mm L (red), 2 x 2.5mm N (black), 2 Earth

How are the 2 FCUs and the socket wired?

Probably not the best connection. The socket is then wired with an additional cable to feed the FCUs, in total 3 Red, 3 Black, 3 Neutral. The FCU in the middle was for a wall light which I took off, it never worked for some reason. That FCU had 2 L, 2 N & 2 E into the IN terminals to feed the RH FCU, then 1 L, 1 N, 1 E in the OUT terminals for the light. The RH FCU had 1 L, 1 N, 1 E in the IN terminals, then 1 L, 1 N, & 1 E in the OUT terminals to connect electricity to the outdoor garage. All cables 2,5mm thick, fuses in the FCUs were 13A.

What is connected to the load side of the 2 FCUs?

As above, a wall light for the middle FCU, electricity to the outdoor garage for the RH FCU. All I will then have is a 2 gang socket and 1 FCU for the garage.

 

[ban-all-sheds]

I've just removed all loose plaster around the old flush box and it would be very difficult indeed to remove it since it is retained by three metal conduits (two unused).

The only thing that looked a bit like nuts is a plastic bit at the end of each conduit, as soon as they enter the box (probably a gomet).

Doesn't seem to me as though the conduit will be retaining the box, then.

I really don't see why you can't remove all the old boxes, and start again.

 

[sparkwright]

Is the conduit with the wiring in it metal?

It does seem unusual for metal conduit (if it is metal) to not join directly to a metal back box. The metal conduit is fixed to the metal box to maintain earth continuity.

The box you describe with threaded holes in each box sounds old, early 50s or older. The conduit looks old too. Presumably the wiring is much newer, perhaps the age of those surface sockets.

Send pictures of where the conduit with the wiring meets the back box, and we may be able to help you to decide how the conduit should join with a new back box.

As ban indicates, it may be just a conduit with a rubber end cap meeting up with the box, but this isn't typical.

 

[Ambergreen45]

Is the conduit with the wiring in it metal?

The box you describe with threaded holes in each box sounds old, early 50s or older. The conduit looks old too. Presumably the wiring is much newer, perhaps the age of those surface sockets.

The conduits are metal. The house was built in the late 40's and was rewired possibly in the 60's according to a neighbour but this isn't sure. I may have to leave surface mounted boxes, after having thought about it because to replace a 2 gang metal box from a 1 gang I would have to break some of the hard brickwork because the plaster is not deep enough. That's how all original back boxes and conduits are, into part of the brickwork to accomodate them before using plaster and that's probably why when the house was re-rired the electricians though it could have been too much work to drill and brake into the hard brickwork, I suppose. I will try and see if I can take a picture though the box is seems slighly smaller than normal and I've got all cables surrounded with temporary seath and insulating tape and the choc box coming out of it at the moment.

 

[ban-all-sheds]

to replace a 2 gang metal box from a 1 gang I would have to break some of the hard brickwork because the plaster is not deep enough.

Stitch drill where you need the hole to be, reach for your bolster and club hammer.

Won't take long.

That's how all original back boxes and conduits are, into part of the brickwork to accomodate them before using plaster and that's probably why when the house was re-rired the electricians though it could have been too much work to drill and brake into the hard brickwork, I suppose.

Yes - sadly there are too many people around who are too lazy to do things properly.

 

[sparkwright]

I wouldn't say it was lazy to fit surface fittings during a rewire though.

If out of date back boxes are present, and no one wants to redecorate, this is of course the norm.

So many post war council houses in metal conduit were re-wired in this way.