Napit assesment coming up, some advice please

[flyingsparks]

Evening.. Next week I have got my first initial assesment with napit. Wonder if anyone here has had one and knows the answers to my questions,

A. Do I need a voltage proving unit to check my meter first or is checking it on the live supply ok?

B. is a multimeter ok to use to test for dead, or should I be using some test probes?

C. Before removing the cover of the fuseboard will he expect me to turn off the main switch?

D. Will they want to see locking off devices used on mcb's and signs?

Not sure how strict they are with all this kind of thing! Any advice much appreciated. Cheers all..

 

[Spark123]

From a common sense approach as opposed to a Napit assessment:

A, No, you don't need to use a proving unit as long as the testers are proved on a similar voltage to that expected, i.e. if you are isolating to work in the consumer unit you may prove your testers before and after use on the live side of the main switch. Where no supply is available to prove though you need a proving unit.

B, No, a multimeter can be set incorrectly hence is not a recommended device to prove dead with. See GS-38, ch17. http://www.hse.gov.uk/pubns/books/gs38.htm

C, I don't see why not, usually they have a cover over the bus bar which it states switch off before removing but can be missing. Anyhow, if working in an enclosure that isn't ip2X (how to tell with the cover on?) then it ought to be isolated first.

D, yes - you need to be locking off MCBs and main switches to ensure a safe and secure isolation.

 

[333rocky333]

Dont take this personally, but I feel you know the answers already.

Us older electricians sometimes discount these things, but there there for your safety.

I feel Someone new starting out should make this everyday practise really

 

[flyingsparks]

Dont take this personally, but I feel you know the answers already.

Us older electricians sometimes discount these things, but there there for your safety.

I feel Someone new starting out should make this everyday practise really

I have been qualified for 10years and so I don't think I fall under the "new" category. Just going self employed, after working for the same firm for the past 13 years having done my apprenticeship with them.

 

[JohnW2]

B, No, a multimeter can be set incorrectly hence is not a recommended device to prove dead with. See GS-38, ch17. http://www.hse.gov.uk/pubns/books/gs38.htm[/QUOTE]
Whilst I'm sure that's the official answer (which the Napit inspector would expect to see) and 'best practice', I think that the reason given by GS-38 is pretty lame. A multimeter set to the wrong range is no more dangerous than a test lamp with a dead lamp/bulb. In both cases, the consequential potential danger can be avoided by following the standard practice (as also mentioned in section 17 of GS-38 ) of proving the test device immediately before and after it is used in anger.

Kind Regards, John

 

[Spark123]

I don't think it is lame at all, a multimeter can be set wrong! My proving unit outputs DC, do I set my multi meter to DC to prove it and then back to AC to check? Or just use the right tool for the job ie my voltage testers?

 

[JohnW2]

I don't think it is lame at all, a multimeter can be set wrong!

It certainly can - that was implicit in what I wrote.

My proving unit outputs DC, do I set my multi meter to DC to prove it and then back to AC to check? Or just use the right tool for the job ie my voltage testers?

Definitely not!! That would obviously carry the risk that you would incorrectly set the multimeter after you had 'proved' it - you must prove your testing device in exactly the same state as you use it!

If the only means of 'proving' you have is with DC, then you obviously cannot use a multimeter, for the above reasons. However, under those circumstances, nor do I think it would be totally safe for you to use one of the electronic '2-pole testers', since I personally wouldn't be totally comfortable that it would work correctly with AC if I had only been able to 'prove' it with DC. Ideally, any testing device shouls be proved not only in 'the same state' as it was being used in anger but, also, with the same type of electricity (AC or DC).

Of course, very commonly you will have the actual AC supply available for proving purposes, in which case I would again say that GS-38's argument against a multimeter is not very strong.

Kind Regards, John

 

[RF Lighting]

What if you accidentally set your multimeter to current instead of voltage and then shove it straight across the incommer?

 

[Spark123]

My fluke 77 will hopefully pop the hbc fuse and take a chunk out of the probes, a cheap multimeter without hbc fusing will probably not be as nice!

 

[JohnW2]

What if you accidentally set your multimeter to current instead of voltage and then shove it straight across the incommer?

I was waiting for someone to come up with that one!

That's obviously a risk, and it certainly happens (I suspect many/most of us have witnessed incidents of that sort with multimeters), but it's got absolutely nothing specifically to do with testing for dead - it's a risk that exists whenever one uses a multimeter to measure voltage. It doesn't detract from the safety of testing for dead, because (in that situation) the multimeter will not 'pass' it's pre-test 'proving' That's why one has to prove!

Kind Regards, John

 

[333rocky333]

Aside from that most meters i have seen had long probes which i would not be happy poking round in a distboard with.

 

[JohnW2]

Aside from that most meters i have seen had long probes which i would not be happy poking round in a distboard with.

Depends on the meter. Don't forget that we're talking about an electrician, and I would expect/hope that an electrician would not be using a meter which did not have (and would not accept) decent probes.

As I've just written to RF, many of these issues being raised really relate to the existence of multimeters with high volts ranges in general - not anything specific to do with 'testing for dead'. Do you perhaps feel that multimeters with volts ranges above, say 50V, should be 'banned'? ... or perhaps all voltage ranges should be banned (a mutimeter on a low mA range connected across a car battery could create quite a bang!).

Kind Regards, John

 

[flyingsparks]

All I was really wondering is if I need to go out and waste my money on something like a voltage proving unit, which I have never had a need for, or will need in the future. I always test on the live supply present before isolation(where possible and fe to do so)

 

[JohnW2]

All I was really wondering is if I need to go out and waste my money on something like a voltage proving unit, which I have never had a need for, or will need in the future. I always test on the live supply present before isolation(where possible and fe to do so)

... but that (your question A) is a totally different question from the one (question B) about whether it is acceptable to use a multimeter for testing for dead. Whatever you use for that purpose (test lamp, '2-pole voltage detector', multimeter or whatever), you need to 'prove' it immediately before and after use. Under most circumstances, you'll have a live supply available for that proving. Just ocacsionally, you won't, and if you then want to 'test for dead' you would need some battery-powered 'proving unit' - whether or not a Napit inspector would expect you to have that facility, I ahve no idea.

However, as I said, this is different from the question you asked about using a multimeter for this purpose - and the 'official' answer to that question is undoubtedly 'no'.

Kind Regards, John

 

[studentspark]

A. Do I need a voltage proving unit to check my meter first or is checking it on the live supply ok?

You need a known live supply. I have a voltage proving unit in the lockup that got wet and don't work to well,

B. is a multimeter ok to use to test for dead, or should I be using some test probes?

Not really, buy a decent voltage tester

C. Before removing the cover of the fuseboard will he expect me to turn off the main switch?

Yes, telling the home owner first

D. Will they want to see locking off devices used on mcb's and signs?

I think if its your first they will want to see you are really safety aware

Don't walk away from board with cover off, explain, what you are doing and common sense. Its a domestic situation, let him know you know what the risks are, won't hurt to put a lock on and takes seconds.
Just be obviously safe and don't do anything which could potential be seen as putting you , the assessor or the house holder at risk.
They do want you to do well.