Amidst much gnashing of teeth I've discovered I forgot to attach bonding
clamps to the shower (a) before I tiled it and then (b) before the
plasterer came at the weekend to skim the rest of the bathroom. OMG.
Shower valve is fed by copper pipes from above in the roof space, so I
have no option but to apply earth clamps up there, and drop the cable
down the cavity wall and bugger up all the new plaster to get through
the noggins; thereby to connect up to the other pipework which comes up
from the bathroom floor (don't ask - previous occupier had it plumbed
this way!)

Anyway... rant over - main question: do I have to bond shower - sink -
bath - towel rail all with one continuous cable (which is what I always
do), or is that just good practice? ISTR reading somewhere that it was
mandatory but can't find anything about it now, and it will be a royal
PITA if I need to.

Secondarily - I'll bond the H&C pipes at the sink; but if I also have a
metal shower bar fed by copper pipes (no plastic anywhere in this
bathroom), do I really need to bond the H and C pipes to that as well?
Doesn't the shower valve act as conductor (or could, eg, PTFE tape in
the fittings potentially act as insulator? Indeed; do both the H&C
pipes feeding the plastic bath also really need to be bonded, given that
they will already be connected by copper pipe under the floor, by virtue
of the sink bonding?

(These are all things I'd normally do, by the way; I'm just wondering if
it's overkill on my part!)

Thanks
David

Lobster wrote:
Anyway... rant over - main question: do I have to bond shower - sink -
bath - towel rail all with one continuous cable (which is what I always
do), or is that just good practice?

Just to clarify - I'm not talking about joining separate cables anywhere
other than at pipe clamps!

David

In article ,
Lobster writes:
Amidst much gnashing of teeth I've discovered I forgot to attach bonding
clamps to the shower (a) before I tiled it and then (b) before the
plasterer came at the weekend to skim the rest of the bathroom. OMG.
Shower valve is fed by copper pipes from above in the roof space, so I
have no option but to apply earth clamps up there, and drop the cable
down the cavity wall and bugger up all the new plaster to get through
the noggins; thereby to connect up to the other pipework which comes up
from the bathroom floor (don't ask - previous occupier had it plumbed
this way!)

It's probably not a good idea to end up with earth bonding clamps
hidden in a wall anyway -- they would be assumed to be missing in
any kind of electrical inspection.

Anyway... rant over - main question: do I have to bond shower - sink -
bath - towel rail all with one continuous cable (which is what I always
do), or is that just good practice? ISTR reading somewhere that it was
mandatory but can't find anything about it now, and it will be a royal
PITA if I need to.

It's good practice to avoid cutting earth bonding conductors
where it can be avoided, but it's not mandatory and don't get
obsessive about it. Make sure connections are good and tight.

Secondarily - I'll bond the H&C pipes at the sink; but if I also have a
metal shower bar fed by copper pipes (no plastic anywhere in this
bathroom), do I really need to bond the H and C pipes to that as well?

Generally, you should bond in the room or immediately adjacent
to the room. You shouldn't assume different pipes which enter
the room are electrically connected outside the room -- even if
they are now, they might not be in the future.

Doesn't the shower valve act as conductor (or could, eg, PTFE tape in
the fittings potentially act as insulator?

It could, and someone could fit a plastic shower in the future.

Indeed; do both the H&C
pipes feeding the plastic bath also really need to be bonded, given that
they will already be connected by copper pipe under the floor, by virtue
of the sink bonding?

Again, don't assume continuity of pipework outside the room.
Someone might do a repair with a plastic pushfit fitting or
a length of plastic pipe.

--
Andrew Gabriel

Lobster wrote:

Anyway... rant over - main question: do I have to bond shower - sink -
bath - towel rail all with one continuous cable (which is what I always
do), or is that just good practice? ISTR reading somewhere that it was
mandatory but can't find anything about it now, and it will be a royal
PITA if I need to.

That's not mandatory - you just need reliable connections. The usual
rules for connections apply: screw clamps must be accessible (without
_too_ much demolition); crimps, soldered joints etc. need not be.

Secondarily - I'll bond the H&C pipes at the sink; but if I also have a
metal shower bar fed by copper pipes (no plastic anywhere in this
bathroom), do I really need to bond the H and C pipes to that as well?
Doesn't the shower valve act as conductor (or could, eg, PTFE tape in
the fittings potentially act as insulator? Indeed; do both the H&C
pipes feeding the plastic bath also really need to be bonded, given that
they will already be connected by copper pipe under the floor, by virtue
of the sink bonding?

Judgement and common sense have to be applied here. Ask yourself "could
a plumber working here easily negate the bonding?" You can rely on
short lengths of copper pipework, including soldered joints, that don't
disappear off into the distance. The bonding must be "in close
proximity to the location" as it says in the OSG. I would not rely on
continuity through compression fittings, and certainly not through tap
connectors which could interpose some horrible mix of boss white, hemp,
PTFE and fibre washers in the way of sound electrical connection.

--
Andy

Andy Wade wrote:
Lobster wrote:

Secondarily - I'll bond the H&C pipes at the sink; but if I also have
a metal shower bar fed by copper pipes (no plastic anywhere in this
bathroom), do I really need to bond the H and C pipes to that as well?
Doesn't the shower valve act as conductor (or could, eg, PTFE tape in
the fittings potentially act as insulator? Indeed; do both the H&C
pipes feeding the plastic bath also really need to be bonded, given
that they will already be connected by copper pipe under the floor, by
virtue of the sink bonding?

Judgement and common sense have to be applied here. Ask yourself "could
a plumber working here easily negate the bonding?" You can rely on
short lengths of copper pipework, including soldered joints, that don't
disappear off into the distance. The bonding must be "in close
proximity to the location" as it says in the OSG. I would not rely on
continuity through compression fittings, and certainly not through tap
connectors which could interpose some horrible mix of boss white, hemp,
PTFE and fibre washers in the way of sound electrical connection.

Thanks, Andy and Andrew - that's been really helpful. (I did manage to
get a single length of cable through the roofspace/cavity
wall/underfloor to all necessary locations in fact, so I'm quite chuffed
with that!)

Given what you say above about what does that say about where you should
ideally apply the pipe clamps under the bath/sink taps: above or below
the isolation valve, which we have to assume may also be a "horrible mix
of boss white, hemp, PTFE and fibre washers in the way of sound
electrical connection"!? Should it be above them to ensure hopefully
the taps are at equal potential? (But aren't the taps' electrical
continuity also still likely to be compromised by PTFE etc??) Bit confused!

David

Lobster wrote:

Given what you say above about what does that say about where you should
ideally apply the pipe clamps under the bath/sink taps: above or below
the isolation valve, which we have to assume may also be a "horrible mix
of boss white, hemp, PTFE and fibre washers in the way of sound
electrical connection"!? Should it be above them to ensure hopefully
the taps are at equal potential? (But aren't the taps' electrical
continuity also still likely to be compromised by PTFE etc??) Bit
confused!

I'd go for below. If you bond the two pipes together (and the bath if
it's metal) then there isn't going to be a voltage difference appearing
between the taps, even if the electrical path through the tap connectors
is somewhat resistive.

--
Andy

Andy Wade wrote:
Lobster wrote:

Given what you say above about what does that say about where you
should ideally apply the pipe clamps under the bath/sink taps: above
or below the isolation valve, which we have to assume may also be a
"horrible mix of boss white, hemp, PTFE and fibre washers in the way
of sound electrical connection"!? Should it be above them to ensure
hopefully the taps are at equal potential? (But aren't the taps'
electrical continuity also still likely to be compromised by PTFE
etc??) Bit confused!


I'd go for below. If you bond the two pipes together (and the bath if
it's metal) then there isn't going to be a voltage difference appearing
between the taps, even if the electrical path through the tap connectors
is somewhat resistive.

Cheers, Andy: done.