I recently had an electrical survey conducted on a house we intend to
buy. One of the main issues that arose was that 'there is no main CPC
(Circuit Protection Conductor) from the suppliers side. Can anyone
explain what a CPC is, whose responsibility it would be to install one
(us or the supplier?) and how much this might cost?
thanks in advance
The CPC conductor is what you and I call the earth wire.
It's rather a glaring omission if there really is "no main CPC
(Circuit Protection Conductor) from the suppliers side". Is this a
rather old installation? If it's old it *might* be that the only
earth connection is one to the incoming water main but this is
definitely not a good idea nowadays with the proliferation of plastic
It's the supplier's responsibility to tell you what sort of earth they
are providing and where you should connect to it but I think that's
all. They *might* (I suppose) tell you that they are not providing an
earth in which case you need to provide your own earth rod and use
RCDs. Is this in the country with an overhead supply?
It's impossible to guess costs without more information. Presumably
this is from a survey/check, does your mortgage depend on it or is it
just something you want to fix?
Thanks for your response -
The installation is quite old - I can't be sure when it was last updated but
the previous occupants of the house were there for 40 years and judging by
the decor didn't do much in the way of home improvements since the 70s so we
could be looking at a system thats not been touched for more than 30 years.
The location is in a residential area of Leeds so I doubt there's anything
unusual about the supply. Since posting the last message I've spoken to the
electricity supplier who says that they reckon the installation is something
that should be done by an electrician at our expense and then they will come
and check that the connection meets the required standards. Didn't explain
what a CPC was though!
Our mortgage offer states that we must get the work done, but personally I'm
more interested in making the electrics safe rather than fulfilling my
mortgage companies legal requirements!
The supplier is under no obligation to provide you with a main
earth connection, and even if they do, you do not have to use it.
Of course, there does have to be a main earth connection, but it
can be via your own earth rod/tapes/plate/... but not via any of
the other services such as water pipe, although if metallic, they
must be bonded to it.
The OP has now told us that this is an oldish house in Leeds so it
seems likely to me that the supply will be either TN-S or TN-C-S, so
there *should* be an earth from the incoming supply I would have
thought. Thus it may be that all that is needed is a piece of (thick)
wire in the right place.
I agree that the supplier isn't obliged to provide an earth but in a
town I would have thought it likely that there is one.
This isnt a problem, since earth rod installs are common and perfectly
acceptable. I would be starting to wonder if about the survey by now.
I'm not saying its wrong, but something isnt squared yet 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.