Bathroom bonding and cables through floors
 

Q1. All pipes in bathroom are plastic, with the exception of the central
heating, which is all metal. I have a "class II" extractor fan and wish to
fit a "class II", isolated, shaver supply. As I understand from the regs,
as explained in this document
http://www.iee.org/Publish/WireRegs/...asticPipes.pdf I now need to
supplementary bond the radiator pipes to the fan and shaver outlets
(despite them being class II devices, incase they are changed to class 1
in the future !) - do I need to run a 4mm cable between rad pipes, fan and
shaver outlets, or can I use the cpc of the fan and shaver outlets as the
supp. bond and run a single 4mm cable upto the lighting circuit, where the
fan and shaver supply originate from ?

Q2. My consumer unit is mounted on a wall approx 10cm off of a suspended
timber floor. A couple of years ago we had a visit from the local mice who
decided to use the hole where my cables come through the suspended floor
as an access point into our kitchen (SWMBO was not amused). What is the
recommended method for sealing such a hole ? I have considered expanding
foam, but a few posts in the archives seem to suggest that expanding foam
and pvc cables should not be mixed. I have considered trunking, but that
still leaves a hole into the consumer unit ....


Cheers,

Jason

Jason Pearce wrote:
Q1. All pipes in bathroom are plastic, with the exception of the central
heating, which is all metal. I have a "class II" extractor fan and wish to
fit a "class II", isolated, shaver supply. As I understand from the regs,
as explained in this document
http://www.iee.org/Publish/WireRegs/...asticPipes.pdf I now need to
supplementary bond the radiator pipes to the fan and shaver outlets
(despite them being class II devices, incase they are changed to class 1
in the future !) - do I need to run a 4mm cable between rad pipes, fan and
shaver outlets, or can I use the cpc of the fan and shaver outlets as the
supp. bond and run a single 4mm cable upto the lighting circuit, where the
fan and shaver supply originate from ?

Good news: the use of CPCs as the bonding conductor is explicitly
blessed in the Regs. The bond should be made "in or close to" the
bathroom - so no relying on "but they're all commoned up back in the
CU"! Depending on what jobs you prefer, you could replace a 2ft-or-more
section of both flow and return piping to your bathroom CH rad with
plastic pipe, to go for the "earth free" route. Not a totally practical
suggestion in normal circs, granted, but worth bearing in mind if you
were thinking of repositioning the rad anyway!

Q2. My consumer unit is mounted on a wall approx 10cm off of a suspended
timber floor. A couple of years ago we had a visit from the local mice who
decided to use the hole where my cables come through the suspended floor
as an access point into our kitchen (SWMBO was not amused). What is the
recommended method for sealing such a hole ? I have considered expanding
foam, but a few posts in the archives seem to suggest that expanding foam
and pvc cables should not be mixed. I have considered trunking, but that
still leaves a hole into the consumer unit ....

Is this hole visible? If not, a scrap of just about anything (wood,
plasterboard, ...) should do the trick; if so, any chance of working
from underneath the board? As for expanding-foam-meets-PVC, the thread
we had ended up saying "almost certainly OK", with no experience of
problems and a plausible claim that expanding foam is polyurethane,
whilst it's polythene which causes the leeching-plasticiser problem.

Stefek Zaba wrote:

big snip
whilst it's polythene which causes the leeching-plasticiser problem.

/s/polythene/polystyrene. Poly(e)th(yl)ene is inert in this context.

--
Andy

Andy Wade wrote:
Stefek Zaba wrote:

/s/polythene/polystyrene. Poly(e)th(yl)ene is inert in this context.

Mea culpa; brain fart. Thanks for the correction.

In article ,
Jason Pearce wrote:
A couple of years ago we had a visit from the local mice who
decided to use the hole where my cables come through the suspended floor
as an access point into our kitchen (SWMBO was not amused). What is the
recommended method for sealing such a hole

I use wire mesh with a size suitable to protect against such things.
Easily fixed to wood with staples. Obviously, make sure any cut ends don't
snag the cable insulation.

--
*A person who smiles in the face of adversity probably has a scapegoat *

Dave Plowman London SW
To e-mail, change noise into sound.