Installing twin and earth edge on ?

[bernardgreen]

When twin and earth is installed in a wall chase it is almost always laid flat on the wall.

Suppose the chase was cut just wide enough that the cable sat in it edge wise and the installer took care to ensure the Neutral was upper most. Then if someone did drill into the cable the drill would hit Neutral first, then Earth and hopefully the RCD would have started to trip before the drill reached the Live.

Maybe if there was no RCD then the drill would short Live to Neutral and/or Earth and trip the MCB

 

[AndyPRK]

I'm not sure where this is going but I guess it would be difficult to inspect know it had been done correctly.

Also it would be a problem on 3+E with the silly new colours where you don't know where N is.

What about switch drops? I guess you could hope the light was off but if your drilling in the room it could be on.

P.s I'm get used to laying cables the correct way round to suit mk accessories rather than having cross over in the back box.

 

[bernardgreen]

I guess it is not practical.

Amazing what silly ideas surface when having a bad day with software that doesn't work as expected........

 

[AndyPRK]

Its not a bad idea. Cheaper than using Alitube of whatever it is.

Bit difficult with cables of 6mm+ I would have thought.

You would need newly developed plastic trucking to hold it in place I would think made to hold various sized cables.

And some marking on the outside of the cable to know easily where N is.

 

[securespark]

I cannot for the life of me remember where I read it, but it is considered bad practice to install T & E cable on edge like that.

 

[AndyPRK]

Because of poor heat dissipation. ?

 

[PrenticeBoyofDerry]

It's a "no no" in the 2391 exam!
When I took mine, it was one of the 12 non-cons on the list to find.

 

[JohnW2]

Because of poor heat dissipation. ?

I wouldn't have thought that would be an issue once it was surrounded by plaster, would it?

Kind Regards, John

 

[JohnW2]

It's a "no no" in the 2391 exam! When I took mine, it was one of the 12 non-cons on the list to find.

Interesting. I would have thought that I (and probably also you) would probably struggle seriously to find a regulation with which it was non-compliant, wouldn't you?

Kind Regards, John

 

[PrenticeBoyofDerry]

Interesting. I would have thought that I (and probably also you) would probably struggle seriously to find a regulation with which it was non-compliant, wouldn't you?

I must admit I did flick through the requirements afterwards, for some clarity and could not find an obvious one that stated it was a non-con. Unfortunately the examiner was a complete **** from the army and it was difficult to get any information out of him why it was a non-con.

 

[RF Lighting]

the reason it's frowned upon is due to the risk of crushing one of the insulated conductors into the CPC by clipping on edge.

I see no issue with a cable on edge in a narrow chase, even with live outermost. You can still hit just live with a screw, nail, drill etc with T&E mounted flat, so there's no difference here imo.

 

[JohnW2]

Interesting. I would have thought that I (and probably also you) would probably struggle seriously to find a regulation with which it was non-compliant, wouldn't you?

I must admit I did flick through the requirements afterwards, for some clarity and could not find an obvious one that stated it was a non-con. Unfortunately the examiner was a complete **** from the army and it was difficult to get any information out of him why it was a non-con.

I strongly suspect that was because he was wrong! Some may consider it 'bad practice' (although I can't really think why), but I do seriously doubt that it is non-compliant with any 'regulation' in BS7671.

Kind Regards, John

 

[JohnW2]

the reason it's frowned upon is due to the risk of crushing one of the insulated conductors into the CPC by clipping on edge.

'Frowned upon' and non-compliant are two rather different issues. I take your point about 'clipping on edge' (not that one would find a clip designed for that, anyway), but that's different from 'installing on edge. As you go on to say ...

I see no issue with a cable on edge in a narrow chase, even with live outermost. You can still hit just live with a screw, nail, drill etc with T&E mounted flat, so there's no difference here imo.

Quite so - I fully agree.

Kind Regards, John

 

[RF Lighting]

The most common thing I see is two twin and earths on edge in the same clip. Not really a problem IMO as long as you don't go in too heavy handed with the clips.

 

[sparkwright]

The most common thing I see is two twin and earths on edge in the same clip. Not really a problem IMO as long as you don't go in too heavy handed with the clips.

I seem to recall doubling up cables with clips that aren't designed to be used like this is also frowned upon.

Double clips that ARE designed for two cables only seem to allow for the cable to be flat on the wall, not 'edge on'.