Best way to protect shower cable buried in wall?

[MisterMuddle]

Hi all. I'm doing some redecorating work and fitting a new 8.5 kw shower. I already have a 10mm2 cable fitted, but there 'was' no physical cable protection, apart from a thin layer of plaster and the old wall tiles. Can I simply cover it with metal sheathing strip and plaster over the top or would a plastic sheath be safer? Another thing, internally the new shower is earthed to the copper heater unit. Do I need to add an extra 'earth bond' wire in there, soldered to the existing earth cable and ran to the cold water supply pipe, also soldered in place, a cable run of 6 inches? Or is that overkill?

Thanks for any replies!

 

[davy_owen_88]

Hi all. I'm doing some redecorating work and fitting a new 8.5 kw shower. I already have a 10mm2 cable fitted, but there 'was' no physical cable protection, apart from a thin layer of plaster and the old wall tiles. Can I simply cover it with metal sheathing strip and plaster over the top or would a plastic sheath be safer? Another thing, internally the new shower is earthed to the copper heater unit. Do I need to add an extra 'earth bond' wire in there, soldered to the existing earth cable and ran to the cold water supply pipe, also soldered in place, a cable run of 6 inches? Or is that overkill?

Thanks for any replies!

Was there a shower fitted there before? If not what was the 10mm^2 cable for or did you install it yourself? There is no need for protection as long as the cable is routed within the safe zones (horizontally/vertically from a socket/switch/appliance). If you installed the cable yourself the work you are doing is notifiable to your BCO.

All conductive parts entering the bathroom (water/gas pipes) should be supp. bonded to the CPC of all circuits entering the bathroom (lights/shower/extractor fan etc.)

You should also have a 10mm^2 green+yellow cable main bonding the services (gas/water) as they enter the property which should be connected to the main earthing terminal.

Davy

 

[MisterMuddle]

There was a 7.5 kw shower fitted before. All I have done is remove the dirty old shower & tiling to replace them with new stuff. I was just puzzled as to why there was no protective sheath over the cable. If I just plaster then tile over the cable again as before will it pass a part P exam?

Cheers for the helpful answer!

 

[davy_owen_88]

10mm^2 cable used for a 7.5kW shower? That's just a tad on the cautious side... How long is the cable from the consumer unit to the shower? Does it run through thermal insulation? What size MCB is it connected to?

There is no such thing as a Part P exam and if you are just replacing the shower and nothing else you shouldn't need to notify the work anyway.

You say no protective sheath... do you mean that it is wired in singles or twin and earth cable? If it is twin and earth and it is run in the safe zones then plastered over and tiled is all the protection it needs (be careful when plastering though to ensure you don't damage the insulation (plastic capping can be used but isn't required).

Davy

 

[scousespark]

There is no such thing as a Part P exam and if you are just replacing the shower and nothing else you shouldn't need to notify the work anyway.
Davy

If this is in a bathroom it is notifiable. Replacing a 7.5 Kw shower with an 8.5 Kw is altering the installation. This is my interpretation.

 

[MisterMuddle]

The 10mm2 T+E cable runs up to the loft, runs across 2 joists (clipped on the top) then turns 90 degrees and is clipped to a third joist, along to the top of the pull switch. Then from the pull switch it goes back into the loft for a 12inches, then down the landing wall, clipped into plastic trunking (though I wish it wasn't!),under the floorboards for 2 feet and down into the CU. There's no insulation anywhere near the cable either in the loft or or otherwise. Anyway thanks everyone for letting me know about the sheathing issue. I'll cover it with plastic stuff just for my peace of mind. I take it that soldering a link from the cold water pipe to the internal earth is a waste of time. I had a look at the cold water pipe where it enters the house, and it is bonded to the earth terminal box. The gas pipe doesn't appear to be bonded to anything, though I'll test for continuity to earth with my trusty multimeter ASAP. It may be connected under the floorboards but somehow I doubt it!

 

[davy_owen_88]

Well according to the NICEIC for non-notifiable work:

fitting or replacing an item of current-using equipment (such as a cooker) to an existing suitable circuit.

And the Part P document:

the fitting and replacement of a cooker or electric showers is not notifiable unless a new circuit it needed.

So assuming the MCB and cable is suitable for the load it isn't notifiable (well according to the above quote).

Davy

 

[davy_owen_88]

I take it that soldering a link from the cold water pipe to the internal earth is a waste of time. I had a look at the cold water pipe where it enters the house, and it is bonded to the earth terminal box. The gas pipe doesn't appear to be bonded to anything, though I'll test for continuity to earth with my trusty multimeter ASAP. It may be connected under the floorboards but somehow I doubt it!

Supplementary bonding requirements.

All metal pipes should be bonded together and then connected to the CPC of every circuit entering the bathroom. Soldering isn't necessary if you use suitable clamps.


What is the rating of the MCB the 10mm^2 cable connected to?

Davy