Testing lighting circuit with no CPC

[Doug]

If a customer would like some minor changes to an old lighting circuit with no CPC, then obviously you should start by recommending that the circuit be rewired. If the customer doesn't want this then, as I understand it, you are still allowed by the regs to work on the circuit as long as that there are only class 2 items which do not need an earth.

How would you go about testing a circuit with no CPC? You can't measure R2 or even R1+R2. About all you can do is the insulation resistance (line/neutral) and polarity.

To put new lighting in a bathroom you can add an RCD spur, but can you test the RCD without using an earth connection, or do you need to use a wander lead?

I would be grateful for any suggestions.

Douglas

 

[slocm3105]

Thats a good question Doug as I have wondered this before. I personally would not install a new light, RCD protected or not, if there was no cpc to the circuit. This is an at risk situation and I would not go anywhere near it unless it was rewired. Who is guna believe you if something happens? You say I made sure all fittings were Class 2?!?! I wouldnt risk it personally. Would like to find out others' opinions and if any reg numbers can be pulled out from the depths of the big red book though .

Regards




Matt

 

[Spudnik]

You are permitted to do various works on the circuits and label the cu accordingly, however, this does not relieve you of any responsibility if anything should happen.

Have a read of this, which is related.

http://www.esc.org.uk/pdfs/business-and-community/electrical-industry/BPG1_08.pdf

 

[Doug]

Thanks, I have already seen the ESC guide but it doesn't give much info on testing or filling out a minor works cert. I understand that ideally you would rewire, but failing that you should remove metal (class 1) fittings. I just wondered if anyone had any suggestions or tips for the testing and forms.

 

[spark1]

I think you would be correct in removing a Class 1 light and installing a Class 11 light in its place where there was no cpc.......however ; it would not be correct to replace a class11 light with another class11 light,in these circumstances unless the work was of an urgent Distress type ..........Comments and reasons for this action would have to be entetred on the E.I.C or M.W.C.

 

[theleshollis]

I went out to quote for a little lighting job today.
The lady wants 2 new lights in her dining room and lounge. There is a open circuit in the supply to the dining room light for me to find as well.

However, I have discovered that there is no cpc in the lighting circuit.

Obviously, the lady requesting the work isn't keen on my ripping the place apart.

There is a 16th edition CU with the lighting circuit on the RCD, so someone has already gone part way down the road.

Having read the code of practice linked to above, I'm wondering if it would be acceptable to add a cpc to the 3 or 4 metallic lights in the circuit, and replace the metal switches with plastic and labelling the CU accordingly?

This would be a halfway house solution, possibly making the best of a bad job?

Any comments?

Les

 

[Des 56]

Having read the code of practice linked to above, I'm wondering if it would be acceptable to add a cpc to the 3 or 4 metallic lights in the circuit, and replace the metal switches with plastic and labelling the CU accordingly?

That would be an adequate course of action as far as I am concerned

You can recomend till your tounge siezes up the need for replacement of the lighting,but it is a very common occurence and also very common for the customer to say no
We are then left with the dilemma of should I do what is the minimum best course of action or leave it for some cowboy to perform on
What you propose is safe and a nigh on perfect improvement,so why the concern ?

If there are existing class 1 fittings and no cpc and the customer says leave well alone,the test to establish safety is an insulation test between the metal of that fitting and any conducive pipework that is within reach,to establish that there is greater than 1 M ohm insulation resistance
As far as metal switches,then advise they are potentially unsafe and leave well alone but note everything on certification and a signed covering letter,in my estimation that would be well above all expected attempts to maintain safety and would stand up to scrutiny by whoever

 

[theleshollis]

Ta for the comments Des. Having only recently gone self employed, and being used to discussing the twiddly bits of the job with others, I thought I'd raise this here. I'm always questioning stuff I do, which I suppose is a good thing.

Cheers,

Les

 

[peteludman]

i thaught that you had to run a earth through to all new light u add and get rid of all old class 1 lights or write them a letter explaning the problem( that covers you then ) so your work will be safe and rcd will work on new lights

 

[Des 56]

i thaught that you had to run a earth through to all new light u add and get rid of all old class 1 lights or write them a letter explaning the problem( that covers you then ) so your work will be safe and rcd will work on new lights

Connecting up class1 lights to a circuit with no cpc is not what was advised,that should not be done at all

The problems are when an existing circuit with no cpc has a class 1 fitting already installed
If you were working on that circuit you would have to remove the fitting or dont work on the circuit

The question was regards installing a cpc to fittings that were to be changed to clas1
In this case where the customer refused rewiring of the whole of the lighting circuit,installing a cpc to those lights would be adequate
Testing of other fittings that were on the circuit but not worked on could be carried out,with a letter or such explaining the existing danger

 

[peteludman]

i was saying any new lights you install you should make them conform to the regs and earth them.
the rest of the lighting circuit without cpc should be noted and the customer should be made aware of the dangers in writing this covers you, your work is safe then and unsafe old stuff is reported to customer it is up to them what they do but you and them have a copy of the notification.

so your work coforms to 7671 and existing installaton has been noted there is a problem

 

[theleshollis]

Thanks for the responses chaps.

I came across a second installation like this yesterday, only more so.
Another customer asked me to take a look at a fault and install a replacement light.
I immediately noticed that there was little in the way of earthing on the circuit, took a look in the loft and found a mish mash of cables that might have been found in a skip and reused. A mixture of PVC twin, T&E, single VIR cables twin VIRs...
There are twist and tape joints all over the place as well.

Also found the cpc of a T&E being used as a switch wire.

there aren't enough in the world for this one.

The fault the customer had reported was due to all the bulbs in one of the fittings having blown over time. This meant that the light in the next room, having been wired in series also stopped working!!

I swapped the knackered class 1 light for a plastic pendant, swapping the connections in it over to undo the series issue. Told the customer about the dangerous nature of the wiring and that he HAD to get the lights rewired, with a follow-up letter this morning.

He's only just bought the place, and said that "It didn't come up on the survey" Not surprised at that, as the DB looks okay and the main bonding is in place, Surveyors don't see much do they?

It's a horrendous job, completely random wiring that is so wrong I couldn't get my head around the fault for a while as I couldn't apply the usual thought process for a relatively normal circuit fault.

The family seem to be relativelyrecent immigrants from Sri-Lanka or similar, on a low wage. I'm pretty sure the work will not get done, but what do you do?

 

[dixon9]

There was an article by the ESC on this subject which provided some guidelines (first link goes straight to a PDF download):

electrical safety council lights without earth - Buscar con Google

 

[Graeme Harrold]

As I have said on other threads, this is why you have a good look at the circuits before lifting a tool. Better to spent 15-20 mins locating the nightmare than having to adopt it once your work is done....

If you aint happy, walk away, but make sure your customer is fully informed. The problem with electrics is we cant shut down or remove dangerous unlike those who work on gas . It can be frustrating.........

 

[simopesh]

I have the same issue where lighting circuit is twin wire cable without CPC. The company that I work for classify it as unsatisfactory code 1. Also, there are plenty of class 1 fitting including tenants bathroom – DIY jobs. We rarely get orders for full circuit rewire!
Example: Westminster city council – Princethorpe, Polesworth, Wilmcote, Oversley, Brinklow and Gaydon house, London W2. (The tower blocks visible from the A40)
90% of lighting circuits are without CPC and nobody is bothered about it!
The only measurement that can be done is the Z line one but it is absolutely useless.