UK Can a 10mm2 Shower feed and a 1.5mm2 switched live for the lights be in the same wall chase?

[collumplz]

Hi,

I'm installing 10mm2 cable into the wall to the loft from the downstairs consumer unit ready for an electrician to terminate both ends.

Previously the shower isolator was a switch on the wall but my intentions are to change this switch to a light switch and instead put a pull cord for the shower. I have chased up the wall vertically, but can I put the 10mm2 and 1.5mm2 cable in the same chase which would be plastered over?

Also how can I get the 10mm2 cable around the steel back box for the light switch in the wall, I am aware i cannot divert away from the permitted zone so could it go behind or through the back box?

Thanks

 

[timhoward]

It's not ideal but they could share a chase. If you use a big enough light switch box it could pass through it. I'd prefer to get the shower in it's own chase.

Terminating 10mm in ceiling shower isolators is unpleasant at best and rarely done well. If close to a wall it can very difficult to adequately tighten the terminals. I see several each year where the terminals haven't been tight enough and it turns into a little heater.
If you have a chance to start again, a wall mounted unit is much easier to install, maintain, and keep safe.

In fact for an easy life, I'd do it the other way around, use the chase and a wall box for the shower isolator, and a pull cord for the light switch!

 

[collumplz]

It's not ideal but they could share a chase. If you use a big enough light switch box it could pass through it. I'd prefer to get the shower in it's own chase.

Terminating 10mm in ceiling shower isolators is unpleasant at best and rarely done well. If close to a wall it can very difficult to adequately tighten the terminals. I see several each year where the terminals haven't been tight enough and it turns into a little heater.
If you have a chance to start again, a wall mounted unit is much easier to install, maintain, and keep safe.

In fact for an easy life, I'd do it the other way around, use the chase and a wall box for the shower isolator, and a pull cord for the light switch!

That wall switch used to be the isolator but we dont currently have a shower in place and my concern is if i plaster over the wall then once I have the shower I'll have to break the plaster again to add the second length of wire from switch to shower, but if the switch is in the loft then I dont have to mess around with the wall.

I just didn't know if it is against regs to pass a cable through a back box for a different circuit, or if theres interference with the two cables being close..

I might take up your way as it seems easier. I'm guessing running the cable vertically so it goes past the back box is not allowed due to permitted zones. but what if the shower cable is is metal conduit would that be sufficient. It is already RCBO protected

 

[timhoward]

Assuming the supply for shower is coming from below, it sounds as though you want to first fix the cable up to back box, and cable from back box to loft with decent length ready for future shower. Circuit can be disconnected at CU until you are ready. Then you can plaster before shower is fitted.

I wouldn’t get into trying to mechanically protect a 10mm cable to avoid running it in zones. Simply not worth the aggro, and metal conduit is not deemed sufficient mechanical protection according to guidance notes.

Either keep it in a straight line with a wall mounted isolator or run it within 150mm of corner of room up to loft if you going for a pull cord isolator.

 

[davesparks]

and metal conduit is not deemed sufficient mechanical protection according to guidance notes.

522.6.202 (ii) in conjunction with 522.6.204 (ii) allow earthed metal conduit as a means of protection for cables buried outside of zones.

 

[timhoward]

522.6.202 (ii) in conjunction with 522.6.204 (ii) allow earthed metal conduit as a means of protection for cables buried outside of zones.

The original post has been edited now and the reference removed so I can't re-check what was actually said, and this does rather makes it look as though my comment came from nowhere.
From the other factors/ideas mentioned I assumed it wouldn't be earthed and they were thinking of indent (v), but if there was intent of earthing it then I apologise for a misleading comment.

 

[davesparks]

From the other factors/ideas mentioned I assumed it wouldn't be earthed

I hadn't considered that, the idea of someone installing LV cables in unearthed steel conduit seems so obviously wrong. But then DIYers do like to do things wrong!

 

[davesparks]

That wall switch used to be the isolator but we dont currently have a shower in place and my concern is if i plaster over the wall then once I have the shower I'll have to break the plaster again to add the second length of wire from switch to shower, but if the switch is in the loft then I dont have to mess around with the wall.

Why not just put a light switch next to the isolator, or move the isolator down to socket height and slightly to the left/right where it is less visually obtrusive. There's no reason why you can't install the outgoing cable from the isolator and leave that safely terminated in the loft ready to connect to the shower later.

How are you planning to extend the shower cable as presumably it is only long enough to reach the current isolator?

I just didn't know if it is against regs to pass a cable through a back box for a different circuit, or if theres interference with the two cables being close..

Not against regs as far as I know but it is bad practice to do it.

Plus a 10mm T&E in a back box doesn't leave much room for anything else in there.

 

[sinewove]

It's not ideal but they could share a chase. If you use a big enough light switch box it could pass through it. I'd prefer to get the shower in it's own chase.

Terminating 10mm in ceiling shower isolators is unpleasant at best and rarely done well. If close to a wall it can very difficult to adequately tighten the terminals. I see several each year where the terminals haven't been tight enough and it turns into a little heater.
If you have a chance to start again, a wall mounted unit is much easier to install, maintain, and keep safe.

In fact for an easy life, I'd do it the other way around, use the chase and a wall box for the shower isolator, and a pull cord for the light switch!

For what its worth,I find the crabtree 50A pullswitch much better for connecting 6 and 10mm shower cables,
Regards,
S

 

[mainline]

For what its worth,I find the crabtree 50A pullswitch much better for connecting 6 and 10mm shower cables,
Regards,
S

Better off with the click prw213 as it has twin screw termination.