In message ,
"Dave Sharp" wrote:
Renovating a house and the guy doing the electrical rewire for me isn't an
electrician (he's a builder) so I've had to get the local building control
office involved who charged me £59.99 and said that they employ a local firm
of electricians to do the inspections for them.
I was told that they need to inspect it when the first fix is complete,
which it now is, and they're coming to see it at 9.00am on Friday. My
question is, what will they be inspecting and looking for?
I've never done it this way around as I only test my own work, but the
aim is to end up with several bits of paper describing the installation
in detail. I suspect that your electricians are probably going to have
to come back when second fix is done, as some of the tests can't be
completed until everything is connected up. How thorough they are will
be interesting - *please* report back when they've been.
On first fix there is a lot that can be done. The main issues are
(OnSite Guide section 9) to "verify that equipment is correctly selected
and erected in accordance with BS7671... [and] not visibly damaged or
defective..."
So at first fix they will be looking to make sure that cables are
properly identified, are routed sensibly and in safe zones or otherwise
mechanically protected, are selected correctly with respect to the
circuit design load etc, that fire barriers which may have been breached
have been made good, and so on and so on. They will also need to be sure
that your plan for the installation is sensible, so will need to be
shown details of the proposed circuits, calculations for design loads
and so on. If you haven't such details then they *should* generate them
themselves, given information from you, but...
Most of the "testing" that has to be done before sign-off can't really
be carried out completely until second fix. The exception is probably
testing on the incoming supply to determine supply impedance, maximum
fault current and earthing arrangements.
After second fix, and *before* the circuits are energised, each circuit
and the complete installation will need to be checked for (OSG 9.3 &
10.2)
quote [except the bits in square brackets]
i) continuity of protective conductors (including main and supplementary
equipotential bonding conductors)
ii) continuity of ring final circuit conductors...
iii) insulation resistance (between live conductors and between each
live conductor and earth) ["live" and "neutral" are both "live
conductors" in this context]
iv) polarity; this includes checks that single-pole control and
protective devices (e.g. switches, circuit-breakers, fuses) are
connected in the phase conductor only, that bayonet and Edison-screw
lampholders... have their outer contacts connected to the neutral
conductor and that wiring has been correctly connected to socket-outlets
and other accessories.
v) earth electrode resistance [if applicable & depends on test method]
Only after this point can the installation be energised. Thereafter,
vi) second check of polarity
vii) earth electrode resistance [if applicable]
viii) earth fault loop impedance
ix) prospective fault current...
x) functional test.
And for all that testing, which might take quite some time if the
electrician hasn't done the installation himself, you usually end up
with at most a half a dozen pieces of paper.
It is much easier for an electrician to certify his own work than anyone
else's as most of the checks mentioned above can be carried out as you
go along. Certainly things like the polarity checks. In order to
thoroughly check someone else's work you should be inspecting every
single connection/accessory and while there are "shortcut" methods to do
this with sockets, there aren't any easy ways to do it with things like
FCUs and light switches.
Hope this helps. Please do let us know what happens on Friday, and if
(when) they do make a second visit, please report back again.
Hwyl!
M.
--
Martin Angove:
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