Shower Cable in wall

[hilme]

Hi there,

[First post - comments gratefully received] I am about the remove tiles and strip plaster board in my bathroom. One of the walls to be stripped has an electric shower on it.

Therefore I have a couple of questions:

1. The cable runs from the loft (above insulation) down inside the stud wall to the shower. When I remove then refit the wall and shower can I upgrade the cable to the next size up so that if in future I bite the bullet and run thicker cable right from the CU I can install a higher rated shower without removing tiles to get at the buried cable?

2. from initial inspection by poking at holes the wall seems to have loose fibreglass insulation packed into it (I presume to reduce sound transmission?) When I replace the wall (with aquaboard) should I replace the insulation also? I don't think that the current 6mm2 cable would be sufficient for the current shower (9.5kW I think) when embedded in fibreglass in a stud wall.

3. I can't see any obvious earth bonding on the shower supply pipe (I know the mains supply is bonded well at the main stop cock under the kitchen sink) where should water pipes be bonded. Its mostly E/F soldered connections - does that make any difference. If I do need to do bonding, can I bond to a ring or lighting circuit? Would feel wrong, but I don't know why it wouldn't be safe!

Thanks for reading,

Chris

 

[EFLImpudence]

1. The cable runs from the loft (above insulation) down inside the stud wall to the shower. When I remove then refit the wall and shower can I upgrade the cable to the next size up so that if in future I bite the bullet and run thicker cable right from the CU I can install a higher rated shower without removing tiles to get at the buried cable?

You could.

2. from initial inspection by poking at holes the wall seems to have loose fibreglass insulation packed into it (I presume to reduce sound transmission?) When I replace the wall (with aquaboard) should I replace the insulation also? I don't think that the current 6mm2 cable would be sufficient for the current shower (9.5kW I think) when embedded in fibreglass in a stud wall.

It would not. Could you leave a channel free from insulation for the cable.
Otherwise you must have the cable touching the board when 6mm² cable can carry 35A and 10mm², 47A.

3. I can't see any obvious earth bonding on the shower supply pipe (I know the mains supply is bonded well at the main stop cock under the kitchen sink) where should water pipes be bonded. Its mostly E/F soldered connections - does that make any difference. If I do need to do bonding, can I bond to a ring or lighting circuit? Would feel wrong, but I don't know why it wouldn't be safe!

Bonding is dependant on several things.
It is not applied just because something is there.

If you have all the circuits in the room protected by RCDs then supplementary bonding may not be required, subject to two other conditions.

Of course, it may not be required anyway.

 

[Chri5]

Run in a 10mm between shower pull and the shower unit. Clip to wood frame of wall

Buy some celotex or Kingspan, since its an internal wall 50mm (about the same as 150mm of glass or loose fibre insulation) in 100mm stud is plenty and allows for a good free air cable run.

 

[Chri5]

Run in a 10mm between shower pull and the shower unit. Clip to wood frame of wall

Buy some celotex or Kingspan, since its an internal wall 50mm (about the same as 150mm of glass or loose fibre insulation) in 100mm stud is plenty and allows for a good free air cable run.

 

[OwainDIYer]

1. yes.

2. yes.

3. Under 17th Ed, equipotential bonding isn't required if all circuits have RCD protection.

If your installation is to 16th Ed, then you need to equipotentially bond all metallic service, as close to where they enter the bathroom, to each other, e.g. hot water pipe - cold water pipe - radiator flow pipe - radiator return pipe - lighting circuit cpc - shower circuit cpc.

You would only bond to the ring circuit if the ring circuit cable runs through the bathroom. The purpose is not to earth the bonding, but to equipotentially bond all metallic services.

 

[EFLImpudence]

The purpose is not to earth the bonding,

Quite - it is in fact to bond the earthing.

 

[RF Lighting]

No it isn't

 

[EFLImpudence]

Yes it is - to bond all parts which are already earthed.

 

[JohnW2]

Yes it is - to bond all parts which are already earthed.

Strictly speaking, it is to bond together all parts which can/could introduce a potential, be that earth potential or anything else - the aim being to ensure equipotentiality between all exposed metal.

Kind Regards, John

 

[EFLImpudence]

Yes it is - to bond all parts which are already earthed.

Strictly speaking, it is to bond together all parts which can/could introduce a potential, be that earth potential or anything else - the aim being to ensure equipotentiality

Yes, I know - because they are themselves earthed.

between all exposed metal.

Not ALL 'exposed' (in the general sense of the word) metal .

Plus the exposed (in the electrical sense of the word) conductive parts of the circuits of the location because they are themselves earthed.

I didn't expect to get challenged on my short comment.

Only parts which are themselves already earthed may require bonding.

 

[SaladFingers]

If they're already earthed, or bonded, then it's (supplimentary) cross bonding.

 

[EFLImpudence]

Extraneous conductive parts are 'earthed' by the ground and so require bonding.

 

[SaladFingers]

Yes but the idea was afterwards to cross bond all bonded and earthed (earthed as in exposed conductive part) together.

 

[EFLImpudence]

Precisely - but parts which are NOT, in one way or another, already earthed should NOT be bonded.

Therefore, only parts which are, in one way or another, already earthed should be bonded.

 

[JohnW2]

Yes it is - to bond all parts which are already earthed.

Strictly speaking, it is to bond together all parts which can/could introduce a potential, be that earth potential or anything else - the aim being to ensure equipotentiality

Yes, I know - because they are themselves earthed. ... I didn't expect to get challenged on my short comment. ... Only parts which are themselves already earthed may require bonding.

You may feel it's a bit pedantic, but the reason I commented/challenged' is because you keep making this statement that the only parts which need bonding are those which are "already earthed".

My main point is that the concept of bonding does not relate only to things which 'are earthed', but to anything which has the theoretical capacity to acquire/'introduce' a potential, which is not necessarily earth potential. Let's face it, if you could guarantee that the things in question were all 'already earthed', in the literal sense, then there would be no need for any bonding - since they would be guaranteed to always be at the same potential (earth potential). Bonding is only necessary because of the possibility that one of the parts in question might acquire a potential other than earth potential (which could only happen if the connection to earth was, or became, 'imperfect'.

Don't forget that, even when defining what things need main bonding, the regs do not define an extraneous-c-p as a conductor which is "liable to introduce earth potential". Instead, they say "liable to introduce a potential, usually earth potential".

Kind Regards, John