No earth continuity on all parts of metal light fitting

[Torpediniforme]

I have just installed replacement ceiling lights, metal 4 light spot bar, I would assumed that the the 2 pivoting metal bars and metal GU10 holder casings would be classified as exposed conductive parts and would have earth continuity like the central part fixed to the ceiling does

I would be grateful for advice to shed some light on this matter!!

 

[kme]

What was the info on the fitting? Do you have a link?

 

[ProDave]

As long as you have connected an earth the the manufacturers earth terminal, you have done all that's required, and you have to trust the manufacturer has done his design correctly.

 

[sellers]

^ yup as long as the green and yellow cable is actually connected to earth. The rest is upto the manufactures of the fitting, as long as you can see no damage. Try scratching your probes into the bars to see if you get a better reading

 

[Manator]

I have seen metal fittings that are actually class II, if this is not the case then it will be down to a bad design. Is it safe to leave it in place? I would say no, if anyone was to replace the lamp under any fault conditions, they are going to get a shock. The lacquer coating could be acting as some form of insulation, but again I would not be happy with relying on this.

 

[Torpediniforme]

Wow, thank you for all your rapid responses, and a wide range too!

Its a Cirrus 4 light Spotlight bar, this is a similar light, as I can't find the exact one on the internet.

Lights by B&Q Bellini 4 Spot Curved Ceiling Light Chrome Plated

(sorry, I can't post a link till I have reached 5 posts)

It is a spotlight bar of the same model line as this;

B&Q Cirrus Dimmable 4 x 50W Halogen Spotlight 6114AF9101 Brushed Chrome Effect

I kept the instructions - no mention of class I or II, and I don't remember seeing the square within a square symbol, or any sign of insulation where the bars joined the central part.

I did ask a retired spark, who also said so long as I have installed to the manufacturers instructions, put personally since I know enough to be concerned I can't use ignorance as an excuse, whether its a design or manufacturing fault, I would have thought in the eyes of the law the responsibility of ensuring a safe installation is mine. Plus I also have a conscience!

If there is a lacquer providing insulation, is this by accident or deliberate?, it could deteriorate with age, plus the lights are in the kitchen , though in the centre, not directly above any work benches/cooker etc

Think I will pay a visit to local B&Q to have another look at one (the customer/friend supplied the ones I fitted) and see what it says on the box, depending what further responses I get, I will probably give B&Q HQ a call to! as I imagine this situation could occur again in the future.

 

[sellers]

personally I think all class 2 metal fittings should have the symbol ettched into them, theres nothing worse looking for an earth on a metal class 2 fitting.

 

[philbas]

personally I think all class 2 metal fittings should have the symbol ettched into them, theres nothing worse looking for an earth on a metal class 2 fitting.

Recalling my PAT testing course, I was told if the symbol is not on then it's class 1, It can be made of solid plastic, but no symbol treat it as class 1. I may be wrong but it's a good rule of thumb.

 

[wozz]

Not be condescending here but are you sure you checked properly, sometimes you have push unbelievably hard with the probes to make a connection to the bare metal through the plating. Personally if i knew the fitting was faulty I would refuse to fit it and give them a trusty pendant for the time being.

 

[batty]

Have you actually checked the wiring before you installed the fitting it maybe that the wiring is not earthed rather than th fitting?

 

[Torpediniforme]

Yes, no problem with R1, RN, R2 continuity, but the only R2 continuity on the metal of the light fitting is on the centre part that the bars with the lights are attached to.

 

[batty]

As others have said its probably the finish that is put on the metal I would check the loop were the wiring enters the fitting and if that is ok get on with your life you have done your bit.

 

[apprentice87]

Hmm, I am not sure that "if that is ok get on with your life" is the most constructive thing i have ever read, although i am sure it was not meant like that!!

Personally, i think that the original poster has done two things;

1, Demonstrated that he has a very good knowledge of how things should be done,

and

2, Demonstrated that he takes a great pride in what he does, and is not satisfied until he is happy in his own mind that things are exactly as they should be.

Personally, i think this shows an EXCELLENT attitude and is something that should be applauded...

Well done Torpediniforme...

 

[batty]

Hmm, I am not sure that "if that is ok get on with your life" is the most constructive thing i have ever read, although i am sure it was not meant like that!!Personally, i think that the original poster has done two things;

1, Demonstrated that he has a very good knowledge of how things should be done,

and

2, Demonstrated that he takes a great pride in what he does, and is not satisfied until he is happy in his own mind that things are exactly as they should be.

Personally, i think this shows an EXCELLENT attitude and is something that should be applauded...

Well done Torpediniforme...

But if you find you have a poor reading at a light fitting what do you do? I would take the fitting down to check the wiring and make sure everthing is tight connected to the fitting but as said a lot of fittings have a laquer on them if they didn't they would get tarnished its how they are manufactured if you are getting no earth at the fitting it has either got to be there is no earth in the feed or its not connected at the light somehow or you are not touching the metal and are touching the lacquer although usually you will get some reading. This will not be a true reading but you could put your probe on a screw which may give a better reading.

 

[steptoe]

note on the MWC as such, or EIC, or whatever,

this is why we provide paperwork.

is it not.

Zs good at terminations, but customer supplied fitting has no available reading.

or something worded slightly better, Ive been off all day, Guinness

 

[Torpediniforme]

I had better clarify as the subject title a little misleading, there is earth continuity to the centre part of the light fitting as per the contents, so I should have made the title 'No earth continuity on some parts of metal light fitting'.

I took my meter into B & Q today, found the light fitting, (says Class 1 on the box), but this time I used a croc clip on one lead, I did get some continuity off the side bar back to the centre part of the fitting - 3.6 ohms. I couldn't get any continuity from the GU10 holder casing though. There did appear to be a lacquer which it looked like the croc clip cut through, a little bit naughty, but then reading some of the posts it looks like this is likely to happen when they are tested after installation!

But in the event of a fault surely this lacquer will be providing insulation/resistance especially if its all intact. How much? Using Table 2Ai page 100 of the Onsite Guide the max allowed earth fault loop impedance on a 5 Amp BS3036 fuse is 7.7 ohms for 0.4s disconnection. My measurement for R1 + R2 on the fitting (between a GU10 adaptor for R1 and the outside of the centre part of the fitting) was 2.3 ohms, plus 0.35 for Ze, plus potentially no continuity of the fault to earth occurs to the casing holding the GU10 lamp, or you could use the 3.6 ohm value from scratching through the lacquer on the bar.

This adds up to 6.25 ohms, less than the max 7.7 allowed but relying on the lacquer being penetrated.

It may not test as per BS 7671 unless its scratched, but in real life if a fault to earth occurs will it heat up and quickly melt the lacquer 'insulation', and what are are the chances of a fault occurring? or some one touching it whilst it the lacquer burns through and the fuse wire is slowly breaking due the the higher resistance of the fault path?

Personally I won't be happy unless I can get a nice low ohm R1+R2 from all parts of the metal fitting without having to cut in to the lacquer, knowing its as safe as possible and meets the regs

Perhaps I do not have a proper understanding of fault paths etc and the regs, so further advice appreciated if any one feels able.

I would also appreciate a tip on how to get my email notifications to responses to this thread, as I believe I have clicked in all the right places in my control panel area etc , or do I need to have done a minimum number of posts?!!!!

 

[D Skelton]

Maybe a very small possibility of a very thin top coat of anti-corrosion/rust applied to the metal product which is preventing you from getting your reading. too thin to see maybe? As others have correctly stated however, it's the manufacturers responsibility as long as you have followed their instructions when installing.