16mm Shower power cable in wall

[gardener1214388]

I intend to fit a shower to a bathroom.
I will use 16mm twin and earth grey.
I want to run the cable behind the tiles; in what was once an outside wall; i.e. it is an 11 inch cavity wall and the cable will have to be chased in.
I will secure the cable with related 16mm grey plastic clips screwed into the wall with 1 3/4 inch x no 6 BZP pozi csk screws at around 7 inch centres.

The cable will be flush with the surface of the plaster leaving about a quarter of an inch to cover the cable with Aquaseal Wet Room sealing tape.
On top of that will be tile adhesive and tiles.

The route of the cable is away from the shower fixing holes.

Summary, brick wall chased, cable fitted screwed, Aquaseal protective water proof tape ontop, tile adhesive on top, tiles fixed on top.

Cable nowadays appears to be covered by plastic channel; a waste of time I believe, does not stop anyone drilling into the cable accidentaly.

My only concern is that the back of the Aquaseal waterproof tape is a sticky mastic and the question would be; would there be any conflict of substance; i.e. grey cable plastic and mastic; although I cannot see this would happen.

The cable is routed direct to its own consumer board breaker; fitted not by myself.

Any thoughts on this project.

 

[JohnW2]

Any thoughts on this project.

This sounds like notifiable work - so it either needs to be done by a self-certifying electrician or else you need to notify it yourself to your LA (and pay them £££).

Do you really need 16mm² cable? What power is the shower and what is the rating of the breaker in the CU?

The buried cable needs to be in 'safe zones' - i.e. vertically or horizontally aligned with the shower unit.

It will also need RCD protection, but I imagine that you probably have that in the CU. Is that the case?

I don't think you need to worry about the Aquaseal tape.

Kind Regards, John

 

[Iggifer]

Capping is there to protect the cable from the plasterers trowel, not from someone screwing/nailing into it in the future

It also holds the cable in place, negating the need for clips

 

[PrenticeBoyofDerry]

As post by John, why 16mm T&E? 10mm T&E is normally sufficient.
And why are you taping over the chase?

 

[gardener1214388]

As post by John, why 16mm T&E? 10mm T&E is normally sufficient.
And why are you taping over the chase?

10 Kwh electric shower and length of cable routed from garage into first floor then up to the shower room.

Taping over the cable; neatly chased to avoid tile adhesive making contact with the cable; just keeping it tidy.

The distance from the face of the cable/clips to the underside of the tiles; 9mm.

I always photograph installations and keep notes for reference.

An earlier comment; plastic cover channels; again it can be difficult to fix them in brickwork; hence properly designed screwed cable clips; makes a definite fixed job especially when using 16 mm cable that is not easily held in position prior to covering and fixing with channel.

 

[JohnW2]

10 Kwh electric shower and length of cable routed from garage into first floor then up to the shower room.

Unless installed within thermal insulation, 10mm² cable would be adequate for a 10kW (not 10kWh) shower (current-wise) and voltage drop with 10mm² cable would only become an issue if the cable run were more than about 60 metres. Having said that, there's nothing wrong with using unnecessarily large cable - other than the increased difficult of installing 16mm² T+E.

Taping over the cable; neatly chased to avoid tile adhesive making contact with the cable; just keeping it tidy.

Fair enough, but tile adhesive would not harm cables. In fact, Method C installation assumes that the cable is buried in plaster (or tile adhesive etc.) and I'm not sure it still applies if you are going to leave an 'air gap' around it, since that would impair heat dissipation. Mind you, since 16mm² is unnecessarily large, that's unlikley to become an issue.

Kind Regards, John

 

[ban-all-sheds]

The route of the cable is away from the shower fixing holes.

But within an allowed zone for concealed cables?

Any thoughts on this project.

This sounds like notifiable work - so it either needs to be done by a self-certifying electrician or else you need to notify it yourself to your LA (and pay them £££).

 

[gardener1214388]

Any thoughts on this project.

This sounds like notifiable work - so it either needs to be done by a self-certifying electrician or else you need to notify it yourself to your LA (and pay them £££).

A - Understood

Do you really need 16mm² cable? What power is the shower and what is the rating of the breaker in the CU?

A - 17th Edition Guide

The buried cable needs to be in 'safe zones' - i.e. vertically or horizontally aligned with the shower unit.

A - Vertically.

It will also need RCD protection, but I imagine that you probably have that in the CU. Is that the case?

A - Both CUs to be replaced with larger units and system checked and cerfified.

I don't think you need to worry about the Aquaseal tape.

A - Thanks, thought so, will talk to Aquaseal just in case.

Kind Regards, John

 

[JohnW2]

Do you really need 16mm² cable? What power is the shower and what is the rating of the breaker in the CU?

A - 17th Edition Guide

What guide are you referring to - the "On Site Guide"? Whatever it is, I don't think many people follow the guidance, since 16mm² for a shower circuit is pretty (I would say very) unusual. As I have said, for all but the worst installation methods, and for cable lengths up to about 60m, 10mm² would be fine for your shower (or any shower).

Kind Regards, John

 

[ban-all-sheds]

I don't think the OSG says that anyway.

 

[JohnW2]

I don't think the OSG says that anyway.

I would certainly doubt it - although I confess that I haven't looked.

Kind Regards, john

 

[flameport]

The OSG (yellow) only has 4 circuits listed using 16mm T&E

Two have 40A protective devices so are not applicable for a 10kW shower.
The others are a 45A BS88-3 cartridge fuse or a 45A BS3036 rewireable.

 

[EFLImpudence]

The OSG (yellow) only has 4 circuits listed using 16mm T&E

May I ask where? (I don't want to read more than the minimum.)

Two have 40A protective devices so are not applicable for a 10kW shower.

Mmmm.

 

[JohnW2]

Two have 40A protective devices so are not applicable for a 10kW shower.

Mmmm.

Mmmm ... very marginal - if that's 10kW at 240V, I make it 39.93A at 230V - which I presume is what you are Mmmming about!

Kind Regards, John

 

[EFLImpudence]