Electrical test for replacing kitchen and bathroom lights

You can change the ceiling rose to a transformer and then run low- voltage lighting. AIUI this would count as like-for-like replacement and not be notifiable provided the low-voltage lighting and transformer all comes in a kit.

But, um, wasn't the wiring for the downlighters already in the ceiling before Part P and you just like-for-like replaced it because it was a bit untidy?

Owain

Especially if you have a habitable room above - fit fire hoods over the downlighters. Otherwise you have breached the fire resisting ceiling.

Owain

Pete Verdon wibbled on Wednesday 21 October 2009 16:46

The testing is not brain damagingly hard - provided you can acquire a multifunction tester, or a group of instruments that can do:

RCD tests (trip time at 1/2 x, 1x and 5x stated trip current in both polarities and ideally a ramp test to indicate the actual trip current, though I don;t think this is compulsory)

Impedance tester (good for measuring fractions of an Ohm)

Optionally an "live" earth loop impedance tester/prospective fault current tester - though you can state the figures that your electricity supplier give you which will be the worst case usually.

Some means to test the earth rod if your supply is TT.

A multifunction tester can usually manage all except the last, some can do that too.

In fact, I would say the inspection side is harder, because you need a reasonable knowledge of the regs to critique the installation - but you need these anyway to do the job in the first place.

The IEE OnSite Guide (17th) would be totally worth the money.

In a nutshell for testing, and this isn't a point by point guide - there may be errors because I'm tired and much is omitted... Merely a gist:

First inspect and test any main bonding (eg water pipes, gas pipes back to the main earth terminal. Visual inspection of clamps, screw tightness, bind wire size etc.

Know your supply parameters.

Visual inspection of your circuit - check screw tightness, cable sizes, terminals, enclosures, cable erection (ooh err) etc.

Test your circuit.

a) Disconnect circuit at CU.

b) Connect L-E of the circuit at the CU end with a terminal block.

c) Measure resistance between L-N, N-E and L-E at every fitting with switches in every poisition (may need to bridge dimmers out with a wire link). Obviously L-N and N-E should be offscale (infinite) and not L-E resistance.

d) Take the highest L-E resistance found for the circuit and write that on the EIC. Check it is less than that required by your breaker/fuse

Any L-N or N-E results indicate wiring errors and need to be fixed.

With any luck you will also have inherently covered much of the functional testing (ie do switches work as expected). Dimmers etc will have to be checked when energised.

The pedantic will repeat that excercise having shorted L-N at the CU end and removed the L-E short.

Then, IR testing,

a) Remove all lamps and bridge all sensitive equiment out (dimmers, SELV transformers etc. Disconnect any other loads like shaver sockets, fire alarms.

b) Do a 500V insulation test between L-N, L-E, N-E at the CU end.

Note the figures and check if they are high enough. Too low = fail.

Remove all the links.

Run an RCD test.

Fill out the form and sign it.

As I say, don't take this as gospel. It's just a rough idea of what you will need to do - if you to take it on, buy a book on the subject - that will help iron out the details...

Then you can PIR the rest of your house with the same skills :)

HTH

Tim

Tim W wibbled on Wednesday 21 October 2009 19:53

I should have said, also remove all loads...