Installing wall cupboard over electrical conduit

[Doug71]

Just burrying cables in plaster was just all to common once upon a time in the Uk, what made it so much worse was they did not just run vertical but also horizontally and diagonally. It does still happen, I have seen places where they have cliped cables to a wall and then the plasterers have slapped there dot and dab boards over the top.

There is a small estate of houses near me which were built in the 70's, they all have wall lights around the living room instead of pendants hanging down. The cables just run horizontally between the lights which is bad enough but the worst part is where the run is broken by a window the cable runs diagonally down from the last light, under the window board and back up diagonally to the next light

 

[mwinfrance]

Just burrying cables in plaster was just all to common once upon a time in the Uk, what made it so much worse was they did not just run vertical but also horizontally and diagonally. It does still happen, I have seen places where they have cliped cables to a wall and then the plasterers have slapped there dot and dab boards over the top.

My house is / was full of cables like that and cut off live wires plastered over, plus the earth was connected to the incoming mains gas copper pipe ( just behind the gas cooker connection point ) , no earth spike. Ma in law ( now dead from old age, at 84, tiny feisty woman ) once "stuck to" the gas cooker by electricity ( clenched hand due to shock ) she was also holding a rolling pin in the other hand, and had the presence of mind to hit the arm that was stuck, with the rolling pin, and knock it off the gas cooker .Broke the arm, but lived.

 

[okeydokey]

Wasn't the earth connected to both gas and water mains? Cross bonded or something? Dunno

 

[mwinfrance]

Nope, not here, earth ( thin bit of 2.5mm copper wire ) just to our gas pipe behind the stove.Both water and gas mains are big bore heavy duty plastic pipes , only the last bit from the property boundary to the house and onwards inside is metal.Meters are at the junctions between plastic and metal. Very common set up here.

I told the gas people 15 years ago to cut the mains gas off, the standing charge alone ( at the time €16 per month ) was about what bottle gas costs us now ( post Covid and Ukraine war ) per quarter. Mains gas consumption charge was about €30.00 per quarter back then 15 years ago

 

[MikeJhn]

My house is / was full of cables like that and cut off live wires plastered over, plus the earth was connected to the incoming mains gas copper pipe ( just behind the gas cooker connection point ) , no earth spike. Ma in law ( now dead from old age, at 84, tiny feisty woman ) once "stuck to" the gas cooker by electricity ( clenched hand due to shock ) she was also holding a rolling pin in the other hand, and had the presence of mind to hit the arm that was stuck, with the rolling pin, and knock it off the gas cooker .Broke the arm, but lived.

Your Ma in law was not stuck to the Gas cooker due to the earth being attached to the gas pipe, there was an electrical short to earth elsewhere that caused that.

 

[Agent_zed]

Just burrying cables in plaster was just all to common once upon a time in the Uk, what made it so much worse was they did not just run vertical but also horizontally and diagonally. It does still happen, I have seen places where they have cliped cables to a wall and then the plasterers have slapped there dot and dab boards over the top.

As long as the cables are in the safe zones (no diagonals) then from my understanding there isn't a problem having the cable just behind the plasterboard.

Regulation 522.6.202 applies where the cable is concealed at a depth of less than 50 mm from the surfaces of the wall or partition and requires the use of an 30ma RCD which I would imagine pretty much all houses now have (and if they don't they should have).

Arguably better to have the cable nice and deep but unless I am wrong (happy to be corrected) on the regs there is nothing against the regs to do this.

 

[MikeJhn]

In a compliant French electrical installation on a TT system (common below 100Ω) the cable from the earth spike will be min 16mm to the consumer unit and then 10mm min to the water and gas and any other extraneous metal parts, but I think there are more P&O electricians in France than cowboys over here.

 

[MikeJhn]

Just thought, P&O electricians may need an explanation, they are someone who read this book on the way over to France: https://www.amazon.co.uk/Electricity-your-French-house-techniques-ebook/dp/B005PZ5G3Q which is out of date and incorrect in some place's.

Definitive French Electrical book: L'installation électrique - David Fedullo , Thierry Gallauziaux -... - Librairie Eyrolles just ensure the copy is the latest as the regulations seem to change every year.

 

[Spectric]

As long as the cables are in the safe zones (no diagonals) then from my understanding there isn't a problem having the cable just behind the plasterboard.

I am talking about when we had brick / block internal walls that were plastered directly with no plasterboard . The right way was to use a metal top hat section over the cable and then the plasterers would cover with the scratch coat, then later plaster.

 

[Agent_zed]

I am talking about when we had brick / block internal walls that were plastered directly with no plasterboard . The right way was to use a metal top hat section over the cable and then the plasterers would cover with the scratch coat, then later plaster.

I don't think you even need a cable covering any more. You can literally plaster straight over them.

I don't particularly like doing that but I have done it on one light switch where the brick was ridiculously hard. I know some people still think this is bad practice but it is within the regs now. Same as wired in flex is now permissible, but many will still say its not the done thing.

 

[Spectric]

but it is within the regs now. Same as wired in flex is now permissible, but many will still say its not the done thing.

The reason this has come about is simply because of the 30mA RCD / RCBO devices so they have taken the attitude that it no longer maters if someone damages a cable because they have minimised the hazzard. In the days of just a fuse or mcb it was very different and many an electrician would find the drill bit melted as they found a burried cable.

I am still very old school and have always disliked domestic electrics and prefered to work industrial, but even in domestic with stud walls I will drop a pvc conduit down to a backbox mounted on a noggin, no dry wall boxes for me.

 

[paulrbarnard]

Brilliant- taking your time is the best approach, not wishing to teach you to suck eggs but don’t assume all the electric cables are in nice visible conduit ( unless it’s a solid brick wall with no plaster or plasterboard ) cables can be hidden anywhere and then lie in wait to catch you off guard . Take all necessary precautions and there are some decent cable detectors available.

Also don’t assume they all run straight up and down / horizontally along the wall…

 

[MikeJhn]

The top hat metal covering on cables would still give way to a drill bit, these coverings was commonly used to help prevent being damaged by the plasterer with the edge of their trowel when the plaster was slapped on, the 50mm depth rule was changed with the advent of RCD/RCBO's as Spectric said above.