Earthing new power shower to cold water pipe?

[jonjj]

Hi all, I hope you can answer my query. To cut a long story as short as possible:

I recently had my old Mira Express power shower replaced (by a plumber) with a Triton Thermostatic power shower. The Triton has an earth connection inside whereas the Mira did not. I'm not sure if this is because the pump was double insulated or whether it was being earthed from the transformer in the roof (see pics) but either way I believe I need to now earth this new Triton one.

I tried my best to pull the old 2 wire cable out and up through the roof but it is set solid in what I can only imagine is cavity insulation (looks like expanding foam). So my question is whether it's safe for me to use an earthing clip on the cold pipe inside the shower and then earthing the other end of the pipe in the roof (where I can easily access it and supply an earth).

Is this safe/viable or will it meet/break any electrical safety standards? I ask because I obviously don't want to electrocute myself/my family and there appears to be a fault in the unit I had installed so the plumber told me to call out a Triton engineer to get the leak fixed (another long story). Obviously if the Triton engineer sees it without an earth he'll just condemn it and not fix the leak. I have until the 30th to try and resolve this and to save the cost of an electrician coming out I was hoping bonding to the pipe would be sufficient. Any help or advice would be much appreciated. I've attached a few photos for your viewing.

Many thanks, Jon.

 

[EFLImpudence]

Which cable supplies the power?

What is the other cable for?

 

[jonjj]

Hi there, the power is supplied by the flat 2 core (with earth) grey cable which you can see tacked on the left-hand side of the picture in the attic. This does have an earth and goes down into the isolator switch. Then the live and neutral come out of the isolator and it's the white 2-wire cable (with red line) which goes down through the ceiling again into the shower unit.

 

[EFLImpudence]

The white cable is not really suitable for that use (no sheath) and should ideally be replaced.

Yes, you can use the water pipe as you propose.

Is the shower circuit covered by an RCD?

 

[jonjj]

Yes, there circuit is on an RCD which the boiler is also on.

When you say the white cable isn't suitable, is that because it's not one of the flat 2-core & earth grey cables or because it's just lying in the roof? It's only powering a small motor so I don't imagine much goes through it...

Oh, one last question, my Dad had a spare earth clip which he gave me which has the letters "A-E" on it. The only ones I can see in the hardware store say "A-D" (i.e https://www.diy.com/departments/b-q-ec15-external-a-d-earth-clamp/178005_BQ.prd)- I can't seem to find what the difference is however, do you know?

 

[AdrianUK]

It looks to me like your 'old' shower was low voltage & was fed, via the black mira PSU in picture three, via a 2 core flex.

Your new shower requires mains. It should not be supplied via that original two core flex - this was intended for low voltage (probably 12 or 24V).

As EFLImupudence has advised above, you should replace the white cable with a 3 core cable which is suitable for use on the mains.


Did your plumber cut the white cable & connect it into the shower isolator? If he did, I suggest you don't use his services again - he has put you & your family at risk.

You do need to fix this before the Mira engineer arrives. Obviously this wiring error is not responsible for the leak but I would strongly suspect that he would condemn this installation and decline to touch it until it is corrected.

 

[jonjj]

Thanks EFLImupudence and AdrianUK for your help and advice. I will therefore call an electrician to come and install a new cable for me - unless you know a way of removing a cable from a wall which appears to be stuck solid in expanding foam/insulation?!

 

[EFLImpudence]

Probably have to remove the shower, then, assuming it is a straight drop can you not pull it down - easier than pulling up by the looks of it - with a strong cord securely attached to the end?

Then pull up a new cable.

Do you think it is just the foam holding it or could there be a noggin or something else holding it. It can't be very far.

 

[jonjj]

It's certainly not far, probably just over 1M. I might try a pull in that case with some rope attached at the top and see if I have any better luck at that. God knows if there's anything in the wall holding it in place, it was probably put in in the 70's so I'm not sure what standards they had back then.

Thanks again for your help and suggestions.

 

[EFLImpudence]

What about where the pipe goes down from the loft?

Is there a space around it (or drill a hole) to poke a stiff wire (or proper electrical fishing rod) down until you can see it at the shower?

 

[sparkwright]

What happens after the 30th?

What room is the other side of the wall? Any built-in cupboards to conceal the wiring?

 

[bernardgreen]

Yes, you can use the water pipe as you propose.

Wouldn't that be dependent on the water pipe being adequately earthed ?

If there was any plastic sections of pipe work then the water pipe may not have any connection to an effective Earth

 

[EFLImpudence]

Wouldn't that be dependent on the water pipe being adequately earthed ?

If there was any plastic sections of pipe work then the water pipe may not have any connection to an effective Earth

No, he is going to earth it in the loft from the T&E in the switch.

 

[jonjj]

@sparkwright The 30th is when I have a Triton engineer coming to have a look at a leak from the unit (although it seems to have stopped leaking at the moment so I might be able to cancel that. I just wanted this fixed by the time he got here at the latest.
The other side of the wall is the landing so it wouldn't look too good having trunking suddenly appear in the middle of the wall...

@EFLImpudence I've tried again tonight to poke around and see if I can get this cable loose but to no avail. It's comes out from the wall at almost 90 degrees and the expanding foam is all around it. I'm guessing it's quite possible the the white cable is actually clipped to some struts on its way down too - either way I can't get it to budge.

Looking again at the original cable it seems quite a thick one - thicker than the 2.5mm cable cores in the cable I bought to replace it (see pics) so surely this is safe enough to run a little pump? Remember it's not powering an element to heat water so I presume it doesn't draw too much power...

@bernardgreen I believe that all the pipes in the house are actually copper as it was built in the 1970's (obviously not as old as your nice cottage ) but I would indeed need to check the continuity before speaking too far. In on of the pics you can see I've loosely placed the earth clip around the hot pipe - this is because I think the hot pipe is already earthed elsewhere - again and either way, I'd have to test it.

I've been quoted "£120 depending on how long it takes" for an electrician to come and run a new cable so it'd be nice to be able to do it myself if possible, especially as I already spend £230 getting the shower installed

 

[EFLImpudence]

When you say the white cable isn't suitable, is that because it's not one of the flat 2-core & earth grey cables or because it's just lying in the roof? It's only powering a small motor so I don't imagine much goes through it...

Because it is not sheathed. It can be flat T&E or flexible cable.

Oh, one last question, my Dad had a spare earth clip which he gave me which has the letters "A-E" on it. The only ones I can see in the hardware store say "A-D" (i.e https://www.diy.com/departments/b-q-ec15-external-a-d-earth-clamp/178005_BQ.prd)- I can't seem to find what the difference is however, do you know?

Nope, not sure either but it doesn't matter.

Table 1 here?
https://professional-electrician.com/technical/clamps-earthing-bonding/