In the bathroom you are supposed (as I understand it) to have
secondary electrical bonding of all exposed metal parts like taps and
metal shaver socket fronts. But does this rule apply to the chrome
plated metal strips that I will have up the edges of my tiled areas
when the work is done? These edge strips will present 10mm wide metal
surface running from floor to ceiling. Two will be touchable when
lying in the bath.
It would be a pain in the neck to have to connect an earth bond to
them - but to retrofit it would be worse!
On 17 May 2007 02:04:41 -0700 someone who may be Robert Laws
If they are liable to introduce a potential into the zone. Taps are
liable to do so, if they are connected to metal pipes which run
elsewhere. A metal shaver socket front is an exposed conductive part
and thus must be bonded as it is liable to introduce a potential if
the socket fails in some way.
Are they liable to introduce a potential? Are they connected to
anything outside the zone? The answer is probably no and therefore
they do not need to be bonded.
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
What you say about shaver sockets is the way a sane person would have
approached it and does actually meet the regs but they are more relaxed:
Electrician's Guide to the Building Regulations - see 5.3.1 "A supplementary
bonding conductor needs to be run to the protective conductor of the
circuits supplying the fixed equipment to include the equipment within the
supplimentary bonding of the bathroom. There is no need for the
supplementary bond to be fixed directly to the piece of equipment."
Fig 5.3a note 2: "Circuit protective conductors may be used as
supplementary bonding conductors."
It is clarified in an interesting IEE document - google for 'section 601
revisited' and click on IEE wiring matters 2005.
In short, we seem to be required to put a wire between exposed metal bits
and a connecting screw in a probably already crowded switch or junction box
just next to live parts. Not sure which is worse - this one or swapping
blue and black over in 3 phase wiring.
As for the OP's question about those metal strips, 'Accessible metal
structural parts of the building' are included in the list of things which
need bonding but these strips are not structural.
I hope that also applies to the individual links on the bathplug chain!
Interesting. Do the people who write these things live in the real world
or (conductive) ivory towers? The principle of bonding in a domestic
bathroom always struck me as overkill if the basic house wiring and
bonding etc was correctly carried out - and unlikely to be done properly
if at all where that was bodged in any way.
*Bigamy is having one wife too many - monogamy is the same
Dave Plowman email@example.com London SW
The whole house RCD idea is certainly deprecated, but that is mainly
because of its lack of discrimination, along with its tendency to
sensitise the RCD with too much legitimate leakage.
This is a new special case that is unlikely to have those problems, and
where I guess they feel that the advantages outweigh any slight
increased risk (i.e. you may lose lights, but chances are the landing
light is on, so opening the door will let you see again), and the
proposed solution is likely to cause less confusion than the current
situation which an awful lot of people seem to have difficulty getting
their heads round.
In practice I think it will depend a little on how installers set about
implementing the new rules. With a bit of thought it would be easy
enough to mitigate the negative effects. Most installs with have a split
load CU with all the socket circuits protected (and hence any
miscellaneous power that is likely to he used in the bathroom). Electric
showers etc frequently seem to get RCD protected even when earth fault
loop impedance does not actually dictate this. So addition of a
dedicated lighting radial for the bathroom from a RCCB on the non RCD
protected side of the CU would maintain the discrimination while
providing the required protection. (This assumes the rules don't insist
that the same RCD protects all the bathroom circuits).
On Sat, 19 May 2007 11:34:11 +0100, "Dave Plowman (News)"
I'd probably not stick the whole upstairs lighting on an RCD just to
overcome the lack of bonding in a bathroom, I'd be more likely to use
an RCD spur for the bathroom lights then it can be fed from the
upstairs lighting circuit and be tidily fitted.
Other option is to run a seperate feed from the CU for the bathroom
lights, but I can only see the RCD for lighting in the bathrrom being
used on retrofit applications to bring an installation up to scratch
so this would probably be as much of a job as fitting the correct
bonding. If it was a new install then I would imagine non RCD lighting
and bonding would still be the norm.
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