Pattress box problem

[Dammit]

We live in a 1930's flat block, it's a concrete frame, internal walls are cinder block and external walls are cavity wall using odd, very narrow bricks- I've never seen them anywhere else.

The bricks are VERY fragile, and in contrast the plaster is very, very strong- you can't get a nail into it.

Cutting the holes into the wall to fit the pattress boxes revealed that there's nothing to really attach them to:

What's the best way of doing this?

(And if anyone knows how to make my images display that'd be great too!)

 

[PrenticeBoyofDerry]

Can you download you picture to an album them upload to post, I cannot view them at all with link/address posted.

 

[Dammit]

Sure, give me five minutes.

 

[Dammit]

(I'm guessing I can't use an external image host)

//media.diynot.com/155000_154463_77828_94247512_thumb.jpg

 

[Dammit]

Right- go here for a small album: https://www.flickr.com/photos/8131181@N05/sets/72157644853848734/

 

[333rocky333]

Pattress box problem

• Dammit
• 26 May 2014
• 1

 

[PrenticeBoyofDerry]

I would recommend that you placed some timber noggins within the cavity void, fixed this to the internal skin via drilling through wall and screw fixing, allowing for a recess if needed in the timber for backboxes to be attached to.
Out of interest, I see a cable entering each socket box from above, are these two sockets also connected horizontally? I am trying to figure out if you have joined cables within void.
Also additional socket outlets, require 30mA RCD protection does this exist on the socket circuit?

 

[OwainDIYer]

You shouldn't really do this if this is the cavity you're breaking into, but:

1. squirt round the outline of the hole with squirty foam. this is to stop your plaster disappearing into the cavity, allow foam to harden.
2. fill the hole with plaster and bed your box into it. support box with a batten until plaster hard.

 

[Dammit]

The sockets connect to each other- there is no cable join within the wall, what's happening there is the wire comes into one, goes into the next, then comes out to go along to the next socket- it's a radial circuit.

And yes, RCD protected.

Timber noggins sounds straightforward.

 

[333rocky333]

In the flikr photo it looks like theres a white pipe between the two metal boxes.
Though agree would be better not having to hunt the pics

 

[AndyPRK]

Out of interest, I see a cable entering each socket box from above, are these two sockets also connected horizontally? I am trying to figure out if you have joined cables within void.
Also additional socket outlets, require 30mA RCD protection does this exist on the socket circuit?

Joke ref garage post/
A question about wire routing or RCD protection was not asked.
/Joke ref garage post

 

[JohnW2]

Joke ref garage post/ A question about wire routing or RCD protection was not asked. /Joke ref garage post

However, if you mean the very recent post, the OP was proposing to install an RCD garage CU, so the new sockets would be RCD protected (even if the existing feed to the garage was not).

Kind Regards, John

 

[PrenticeBoyofDerry]

Joke ref garage post/
A question about wire routing or RCD protection was not asked.
/Joke ref garage post

I was wondering if the best consumer unit to get is 40A 30mA RCD. Would a 30amp supply be ok for this consumer unit?............

Also is it ok for 2x fluorescent lights to run of the rcd?

The OP seemed to suggest that RCD protection would be installed, so if you write your own jokes, I suggest you find someone to compose them for you and get the material right. I hear Brucie may have some free time coming up