Fixing conduit to wall before plastering?

[Sparrowhawk]

Last week I did my first chasing into plastered cinderblock walls for a new socket and light switch. An electrician came and wired everything up, using 20mm plastic conduit, and I now want to plaster over them.

 

However - I can't get the conduit to stay at the back of the chase. The electrician slapped some filler behind to hold it in place but it didn't stick to the dusty cinder block. Perhaps I didn't make the chases deep enough and it's meant to hang mid-way in the chase, but I wasn't expecting how bulky the conduit would be.

 

Is there anything that will stick it in place or will I need to nail or screw the conduit to the wall before plastering?

 

And next time, is there some narrow, flexible capping I can fix over the cable that will hold the cable tight against the wall?

 

 

[Pocster]

Expanding foam ?

[Russell griffiths]

Pull the conduit forward, splash a load of water and pva mix into the chase to wash out the dust and prime up the dry blocks. 
get 4-5 large head clout nail, push the conduit back in and use the nails at the side of the conduit to trap it in place, you should be able to nail into the block or joints. 
 

slap some bonding into the chase, finishing it 5mm low of the surface, plaster over the bonding. 

[Mike]

As per @Russell griffiths, nailing is with clout-head nails either side is by far the easiest. Personally I've never found it necessary to prime with PVA, but certainly squirt water to damp the chase well before filling.

 

First, however, loose those gaps in the conduit to make it continuous and tight up against the back-boxes (there's no point in having a conduit that's blocked in 3 places). That could be replacing it, or just add another section, taping the sections together with insulation tape to make it continuous.

[Sparrowhawk]

Thanks chaps, priming up now and I will go and get clout nails when the hardware shop opens tomorrow.

 

26 minutes ago, Mike said:

First, however, loose those gaps in the conduit to make it continuous and tight up against the back-boxes (there's no point in having a conduit that's blocked in 3 places).

 

I thought the conduit was required by regulations to somehow stop anyone drilling into the cable - which as the cable is in the safe zone above/below a socket, and the conduit fairly thin plastic, doesn't entirely make sense to me.  Is it there instead to allow for rewiring in future? And this could be compliant without it?

 

I'd have thought a nice U channel of 0.5mm steel over the cable would be better if one wanted to prevent peple drilling into it...

[Mike]

36 minutes ago, Sparrowhawk said:

I thought the conduit was required by regulations to somehow stop anyone drilling into the cable...  Is it there instead to allow for rewiring in future? And this could be compliant without it?

Yes, it's for future rewiring and to protect the cable from the plasterer, though the latter shouldn't be an issue in your case!

 

99% sure that it's not required by the Wiring Regs, but I'm not an electrician.

[crispy_wafer]

clean out as above, squirt or two of ct1 behind, then a couple of bits of battening screwed to wall horizontally over the capping as a temporary prop till the ct1 goes off