I just has a Corgi round to do a landlord's gas safety certificate. He
issued it, but pointed out two minor areas of concern which he says wants
sorting - the gas hob needs an isolation valve (which can be in the void
behind the built-in oven); and secondly, in said void there is an elbow in
the gas pipework with compression fittings, which he wants replaced with a
I didn't really think about it till after he'd gone; but (a) what's the
point of having an isolation valve in an inaccessible location and (b) if
there's a problem using compression fittings with gas... don't isolation
valves usually have these anyway?
He also pointed out that if I didn't want to fail my electrical inspection,
I would need to fit earth bonding across the 5 copper pipes entering and
leaving the boiler (which is neither in the bathroom or kitchen). That
one's news to me... is he correct, anyone?!
On Thu, 09 Dec 2004 19:14:56 +0000, Lobster wrote:
The issue is that the hob requires an isolation valve. I'm not sure what
the industry standard category would be if there isn't one. NCS I would
think, just possibly AR. See FAQ.
The compression joint is about accessibility it would be poor practice to
(say) put one under a wooden floor. My view is that a compression joint
behind a built-under oven is OK. If the others in the game read this how
would they view things?
I beleive so. This is more about making sure that the CH pipes are bonded
to earth than supplementary bonding in a wet location - IIRC.
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Thanks for this Ed - checked the FAQ but can't find NCS - wassat then?!
(also couldn't find a mention of the need for an isolation valve but as it's
your FAQ I'm sure you're right!)
Just seemed to me an odd stipulation if he's *telling* me to fit another
compression fitting (ie on the isolation valve) in the same place where he's
told me to remove an elbow because it *has* a compression fitting...
At the last visit of my CORGI engineer, he advised bonding all the copper
pipes from the gas boiler. Even wrote on the certificate that the
householder would carry out remedial work necessary.
Email address in posting is ficticious and is intended as spam trap
Personal mail can be sent via website.
View my auction items on eBay & eBid:-
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com ).
Definitely... the gas supply is already properly earth-bonded, which he also
checked - he was pointing to the 5 pipes (as identified in Christian's
reply) entering/leaving the boiler.
(All but the gas pipe were actually already cross-bonded in the bathroom
next door, but that didn't help, apparently!)
It certainly doesn't make sense to me. If all services are cross bonded at
the entry point, and a boiler is earthed by its normal electrical
connection, why cross bond pipework at it? And as well as cross bonding,
has it got to be run back to the main local earth?
*Be nice to your kids. They'll choose your nursing home.
Dave Plowman firstname.lastname@example.org London SW
Wiring regs require main equipotential bonding for the CH pipes, and this
"shall be connected to the main earth terminal at the origin of an
If they are not currently, this is probably this is what the Corgi is
413-02-02: "In each installation, main equipotential bonding conductors (see
table) complying with Section 547 shall connect to the main earthing
terminal for that installation's extraneous-conductive-parts including the
following: water service and gas installation pipes; other service pipes and
ducting; central heating and air conditioning systems; exposed metallic
structural parts of the building; the lightning protective system'.
What odds would you like?
I think you are taking this too literally. The meaning you are proposing
it has would require every separate piece of central heating pipe to need
it's own bonding wire as you are saying the compression joint doesn't
provide guaranteed earth continuity. This is obviously a nonsense. And if
the joints around the system have guaranteed conductivity then so do those
at the boiler.
Indeed implemented this strictly, every RSJ would need an earthing terminal
which would be insane.
Also this paragraph is out of date - lightning protective systems do not now
go to main earth - this destroys modems and the like - they must have their
own separate ground connection.
I don't really buy the compression fitting stops continuity argument. If
they interpreted it like that, supplementary bonding would be mad too. For
stuff like this, you don't need a 100% guarantee of continuity, just
something to improve the odds. All I think you need to do is put a couple of
straps on and take it back to the earth block. Just like with the gas. No
more, no less. Really not onerous. Honest.
Only if exposed.
Actually, there was a recent case where a workman was killed because there
was live buried metal work and the wiring committee were discussing if this
had implications for future changes - it only applies currently to exposed
metalwork. Briefly discussed in here:
See this bit on the right of page 1: "The previous guidance of the joint
committee has been that steel framework would generally require neither
earthing nor main bonding provided insulated and sheathed cables were used
...." I don't think they will change it though, 'cos as you say it would be
Interesting, don't know anything about them. But I would have thought
"lightning protective systems" would be outside the building anyway, so
would not need to be covered anyway. Odd.
Outside, so hopefully you would be okay. I think the equipotential zones are
only required inside the building
Now that is an interesting thought. I read something somewhere about the
danger of cross-bonding metalwork that was exposed to both the inside and
the outside because, although it is safer for those inside the zone, it can
create a hazard to people outside of it.
It is. Almost all metal pipework will be. If it might be connected to earth
Extraneous conductive part: "Metalwork that is not part of the electrical
installation, and which is liable to introduce a potential, generally earth
potential" ( c.f. Exposed conductive part. )
Here, have a look at this thread on the IEE forum discussing whether a
suspended ceiling (!) is such a part:
(Verdict, No - fortunately). But it goes to show what we are dealing with.
Are you really sure you want to go "All in" on this one ??? I've got a big
stack of chips here.....
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.