NICEIC technical help.

[RF Lighting]

Just found this gem on the voltimum website.

Question 1: When a metal conduit bush and coupling arrangement is used to connect together two plastic adaptable boxes (with 230V cables passing through the coupling), does the coupling require earthing?

Answer 1: That will depend on whether you feel that the gland is an extraneous conductive part - in other words, is it likely to introduce a potential? The only way that will happen is for the cables inside to be damaged, and to be touching the metal bush at the same time.

Our question is - what is the likelihood of that happening? Based on a risk assessment of that and other probabilities, you can make a decision.

Question 2: Thank you for answering my first question, but your reply has left me somewhat perplexed. An extrananeous-conductive-part is a part liable to introduce a potential, generally earth potential, and not forming part of the electrical installation.

In my question, the coupling is definitely forming part of the installation and, as such, I would assume it should be classed as an exposed-conductive-part, so would the coupling require earthing?

In short, if the NICEIC was carrying out an inspection of an installation, and found the situation which I described in my original question, would you ask for the coupling to be earthed?

Answer 2: We are sorry if you were left perplexed by our reply - as regards to the coupling being classified as extraneous or exposed conductive part.

The answer still remains the same - as the installer, you need to decide, (as a competent electrician) what are the possibilities of the couplings becoming live?

Everything around the couplers are Class II, so the only way they will become live is by means of direct contact with a live part. If the installation has been carefully installed, then the likelihood of that happening is very remote.

Your decision will be made on the basis of a risk assessment. If the NICEIC was carrying out an assessment, you - as the installer - will be able to give a confident reply based on reasoning concerning the above points.

We cannot give a generic answer for every situation because the questions we have raised above may have different answers depending on the environment where these couplings are placed.

Please consider Regulation 410.3.9, as this puts things very clearly.

clicky

 

[EFLImpudence]

Better bond it, then, just in case.

 

[securespark]

I'm all for going back to the 15th where everything that moved (and stuff that didn't) was bonded regardless!

This one:

http://www.voltimum.co.uk/news/1860...e-switch---does-this-comply-with-BS7671-.html

 

[EFLImpudence]

Please consider Regulation 410.3.9, as this puts things very clearly.

It states that it should be earthed.

 

[333rocky333]

I dont think that was an unreasonable question and i for one avoid using metal in that situation, i have seen as no doubt many have, termination wiring burnt up and still live, sometimes up to about 50 mm and this could quite easily be within said coupler.
I have often wondered why a plastic coupler does not exist rather than using two end couplers.

 

[securespark]

You're right. To avoid that situation, you could use PVC couplers to join PVC boxes.

 

[333rocky333]

BAS i recall once used a plastic flex gland to join two boxes and it looked neat, he said at the time that a 20mm plastic bush screwed into the removed head bit, though ive yet to see one of these glands personally.

 

[Adam_151]

With 6491x its a non-compliance.

With twin and earth it would be one of those kinda grey areas, although I wouldn't like to see it

 

[securespark]

A non-compliance with PVC or metal couplers?

 

[RF Lighting]

With metal I'd say it's a non-compliance.

No problem with a PVC coupler.