Help! Electrical cables conduit issue in wall

[djlest]

Help!! im having a bit of a dilema and hoping someone experienced could shed some light and possible solutions?

 

Currently i have chased the walls to lay some extra cables for power outlets, this is an old house with red brick & render.

 

unfortunately they really skimped on the concrete render and i now only have about 2cm between the red brick and top of render. This means i am struggling to hide the yellow conduit as it just cannot go deep enough against the red bricks.

 

I considered chasing deeper into the red brick but they are bloody hard and not very thick, i was trying to avoid ruining the houses structural integrity just for some conduit. I also considered making holes in the red brick and hoping i could feed conduit between what may or may not be double cavity walls, but i imagine they are rough as hell and full of cement, also i dont know how easy feeding the piple will be with ceilings and floor already in.

 

i have been considering scrapping  the yellow conduit and using VAF triple core, but i know this is not to thai regulations & moisture, heat, deratings are going to be issues if i take this route.

 

another option i considered was white plastic capping, but even that only leaves about 1/2 cm for render if im lucky.

 

any suggestions please?

See pics below for ideas

[Bobtheblob]

I would give up on chasing the wall. Re- plaster and use plastic trunking on the exterior of the wall. It might be uglier than hidden trunking but it seems to me the best solution for the problem. 

[chickenslegs]

Clad the wall with gypsum board over the top of the conduit?

[djlest]

Yes thanks for that, i would love to take the easy route but unfortunately this is not an option. The cables need burying !

[djlest]

Yes i have considered this also but as there are about 10 additional power outlets and its a pretty big area. Plus tiling over it in the kitchen, i would rather bury the cable.

 

in the UK its actually very common to bury VAF above brick and then plaster over then wallpaper. But hot temperature are not usually an issue so im wondering how is it ok there but not here?

[sometimewoodworker]

31 minutes ago, djlest said:

any suggestions please?

There is cable rated for direct embedding in concrete it will be considerably smaller than the trunking though you will have to derate it (probably -25%) or use a larger size cable as it’s heat dissipation is limited. It will easily fit in your chases.

 

it’s not usually done here due to the higher cost of the cable 

Edited May 11, 2022 by sometimewoodworker

[warrima]

I had a similar issue in my condo i wanted a few extra outlets. I used armoured cable that we wire our industrial machines with at work. It has steel armouring under the sheath. 

[djlest]

 

41 minutes ago, djlest said:

Yes i have considered this also but as there are about 10 additional power outlets and its a pretty big area. Plus tiling over it in the kitchen, i would rather bury the cable.

 

in the UK its actually very common to bury VAF above brick and then plaster over then wallpaper. But hot temperature are not usually an issue so im wondering how is it ok there but not here?

 

39 minutes ago, sometimewoodworker said:

There is cable rated for direct embedding in concrete it will be considerably smaller than the trunking though you will have to derate it (probably -25%) or use a larger size cable as it’s heat dissipation is limited. It will easily fit in your chases.

 

it’s not usually done here due to the higher cost of the cable 

 

39 minutes ago, sometimewoodworker said:

There is cable rated for direct embedding in concrete it will be considerably smaller than the trunking though you will have to derate it (probably -25%) or use a larger size cable as it’s heat dissipation is limited. It will easily fit in your chases.

 

it’s not usually done here due to the higher cost of the cable 

Thanks yes that could potentially work, i am struggling to find triple core vaf 2.5mm at the moment, its not cheap or easy to find let alone moisture resistant. Im not sure if they would have larger vaf here as it would be really hard to work with. Hmmm food more thought…

Edited May 11, 2022 by djlest

[bankruatsteve]

Just use the conduit as planned.  Let the render guys work it out. 

[BritManToo]

2 hours ago, djlest said:

Thanks yes that could potentially work, i am struggling to find triple core vaf 2.5mm at the moment, its not cheap or easy to find let alone moisture resistant. Im not sure if they would have larger vaf here as it would be really hard to work with. Hmmm food more thought…

Single core 4mm, I pay 100bht for 10m, glue a strip of plasterboard over the top to  cover/level then render, forget the conduit.

Edited May 11, 2022 by BritManToo

[Daffy D]

I would be reluctant to bury plastic conduit under a thin layer of plaster. Could lead to future problems, screws for shelfs, nails for picture hanging and who knows happens in the future when the location of the conduits are long forgotten.

  

[sometimewoodworker]

4 hours ago, djlest said:

 

 

 

Thanks yes that could potentially work, i am struggling to find triple core vaf 2.5mm at the moment, its not cheap or easy to find let alone moisture resistant. Im not sure if they would have larger vaf here as it would be really hard to work with. Hmmm food more thought…

It is easy to find if you go to an electrical supply shop, though what you actually want is 2 x 2.5 SQ. MM VAF-G cable though probably 2 x 4 SQ. MM VAF-G is more appropriate due to the derating requirement.

This is some I have as excess from a recent project, it was in stock no problem.

Edited May 11, 2022 by sometimewoodworker

[sometimewoodworker]

1 hour ago, BritManToo said:

Single core 4mm, I pay 100bht for 10m, glue a strip of plasterboard over the top to  cover/level then render, forget the conduit.

While you are free to do what ever you like in the privacy of your home. That is remarkably bad advice to give, single insulated cable in a wall!!! 

[transam]

My place has the same walls as you, I have about 40 outlets around the house in wall boxes. The cables are run through that yellow plastic trunking, so it seems it can be done.

PS. The grey plastic trunking is smaller in diameter, see if your cable will fit, or use single cables, not sheathed..

[BritManToo]

26 minutes ago, sometimewoodworker said:

While you are free to do what ever you like in the privacy of your home. That is remarkably bad advice to give, single insulated cable in a wall!!! 

Nothing  you do will protect wires from a drill/screw/nail going through.

An air gap is more important to allow heat to dissipate if the wire gets hot.

Conduit is used to discourage vermin chewing the wires.

Edited May 11, 2022 by BritManToo

[djlest]

Thanks for everyones replies i appreciate it. I think the conduit & single core is to prevent overheating, marginally protect vermin chewing as its still only plastic.

these red brick walls really heat up mid afternoon, i can touch the walls on the inside of the house and they are really hot. So yes air space preffered, i just dont see anyway to get that space since i have less than 2cm cleArance.

 

3x 4mm cables plus plasterboard then render? thats going to be tough to pull off plus not really much space.

 

i wonder if maybe i can use vaf 2x2.5 and seperate earth taped to it. Then feed that 

down in between the red brick cavity if there is one.

 

one other point to mention, there is no electricity hooked up the meter was removed as previous owners did not pay.

so there may well be an inspection to get the new meter.

[KannikaP]

6 hours ago, djlest said:

Yes thanks for that, i would love to take the easy route but unfortunately this is not an option. The cables need burying !

Why?  All the power cables in my house are down the corners of the room which after a coat of paint, are invisible.

Who's looking anyway?

[Daffy D]

Have you considered surface mounted  cable trunking.

 

I have it, straight down from the ceiling to the socket/Switches.

 

Comes with self adhesive backing, simple and easy to fit.   

 

Looks Ok. 

 

 

 

 

[djlest]

36 minutes ago, Daffy D said:

Have you considered surface mounted  cable trunking.

 

I have it, straight down from the ceiling to the socket/Switches.

 

Comes with self adhesive backing, simple and easy to fit.   

 

Looks Ok. 

 

 

 

 

Yes i was playing with some today, considering using it as it is thinner than yellow conduit, i could possibly bury it in the already chased walls but there wont be much room for air i guess.

[sometimewoodworker]

15 hours ago, djlest said:

i wonder if maybe i can use vaf 2x2.5 and seperate earth taped to it. Then feed that 

Why not use the 2 X 2.5 VAF-G that I illustrated above? There are your 3 x 2.5 conductors.

[Crossy]

That small square trunking stuff looks like a good idea, singles in there and you're good to go.

 

Unless the load is large and constant I'd not worry about 2.5mm² singles overheating. There's nothing to stop you using a 1.5mm² earth conductor to gain a little more space.

 

[BritManToo]

15 hours ago, djlest said:

so there may well be an inspection to get the new meter.

They only look at the fuse box, if that.

PS. wear workman's gloves then your hands won't look like that.

Edited May 12, 2022 by BritManToo

[djlest]

1 hour ago, sometimewoodworker said:

Why not use the 2 X 2.5 VAF-G that I illustrated above? There are your 3 x 2.5 conductors.

Yes your right the vaf-g looks great, i will have to get a roll. Could come in useful

[djlest]

1 hour ago, Crossy said:

That small square trunking stuff looks like a good idea, singles in there and you're good to go.

 

Unless the load is large and constant I'd not worry about 2.5mm² singles overheating. There's nothing to stop you using a 1.5mm² earth conductor to gain a little more space.

 

Thanks crossy thanks for your feedback, always appreciated.

yes the trunking seems to fit better in the walls although a bit tight..

 

Im not sure if it meets electrical standards or what the derating would be?

 

Is 2.5mm okay for 24btu aircons or 4mm?

i also have 2 hot water heaters to figure.

[djlest]

10 hours ago, Daffy D said:

Have you considered surface mounted  cable trunking.

 

I have it, straight down from the ceiling to the socket/Switches.

 

Comes with self adhesive backing, simple and easy to fit.   

 

Looks Ok. 

 

 

 

 

Yes actually i am going to try and use it and bury the white trunking under render. Much thinner than the yellow conduit. It may well work without the vaf!  Thanks

[Crossy]

11 minutes ago, djlest said:

Thanks crossy thanks for your feedback, always appreciated.

yes the trunking seems to fit better in the walls although a bit tight..

 

Im not sure if it meets electrical standards or what the derating would be?

 

Is 2.5mm okay for 24btu aircons or 4mm?

i also have 2 hot water heaters to figure.

 

If it's buried nobody will ever know although I personally wouldn't put the VAF in there, singles would be fine.

 

If you do go with VAF in the trunking/conduit de-rate to 17A (in reality you are never likely to get near that on an outlet circuit). Our wiring is in chased conduit, of course it was done during construction so the mess wasn't an issue.

 

24,000 BTU A/C will use about 2.4kW at full chat -  11A - No worries whatever on 2.5 unless the run as very long ???? 

 

The biggest water heater you could put on 2.5 would be 4.5kW - 20A or so - Might be too small if you are up-north or like DIY skin removal.

 

 

[BritManToo]

15 minutes ago, djlest said:

Is 2.5mm okay for 24btu aircons or 4mm?

i also have 2 hot water heaters to figure.

My house has

4mm wires (each with their own MCB) to the A/c, water heaters and oven. 

2.5mm to everything else. 

Edited May 12, 2022 by BritManToo

[Daffy D]

If you are going ahead with burying the cables in plastic conduit, remember the basic rule.

 

Only run the conduit either vertically or horizontally never diagonally.

 

When drilling holes in the future you can avoid hitting live wire by keeping away from vertical or horizontal lines from any electrical point.

 

People who for, convenience bury cables diagonally from an existing power point to another are asking for trouble.

 

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