Fluorescent light fittings not working....

[JohnW2]

.... it was effectively explaining why even a '2-pole tester' could be misleading if (as effectively is the case with a neon screwdriver etc.) it were used to measure the potential difference between a conductor of interest and earth - since, again, that would not detect a 'broken neutral connection'.

Perhaps more importantly, I probably should have added this about the converse ....

... that this also illustrates that when using a '2-pole tester' for 'testing for dead' it is essential to test (from L and N) to earth (and ideally a 'known good earth', not just a convenient nearby CPC), and not just between L and N, since otherwise one might miss a 'live L' in the presence of a broken neutral.

We should perhaps makes sure that people understand this when we advocate use of a '2-pole tester' for 'testing for dead', since probably the most obvious (and maybe only) thing they might otherwise do would be just test between L and N.

Kind Regards, John

 

[John D v2.0]

Electrical safety rules dictate you must test first that the measuring device detects a voltage, then isolate, test between all conductors and earth, and check the tester again with a pricing unit.
In this case the op is testing for live not dead.

 

[JohnW2]

Electrical safety rules dictate you must test first that the measuring device detects a voltage, then isolate, test between all conductors and earth, and check the tester again with a pricing unit.

Indeed so (and between the conductors themselves, not just to earth). My point was that the need for this has been underlined by what BAS and yourself have just written, but we perhaps don't always stress this (at all or enough) when telling people to use a 2-pole tester for 'testing for dead'.

In this case the op is testing for live not dead.

Indeed. In fact more than just testing for 'live potentials' (which is what the OP was trying to do) but, rather, also (per BAS's point) testing for a 'complete circuit'. However, as above, what you two were saying made me think of mentioning the important point about 'testing for dead'.

Kind Regards, John

 

[John D v2.0]

I added the "and earth" as an edit afterwards hence the unclear wording, but you made a good point.
I don't even own a proving unit!

 

[JohnW2]

I added the "and earth" as an edit afterwards hence the unclear wording, but you made a good point. I don't even own a proving unit!

Well, I do have battery-powered inverters which I could use, but I confess that I don't generally use them to 're-prove' the tester after 'proving dead'.

If one 'proves' the tester (which I usually do on the circuit concerned), isolates, and then finds that the tester 'proves' dead, it would seem incredibly improbable that the tester will have failed during those few seconds (unless it is a single-bulb 'testing lamp'**). I must confess that, as a last stage, I often do, as a final step, apply a neon screwdriver or suchlike, but that's more a matter of habit than anything else.

I feel that one advantage of doing the initial 'proving' on the circuit concerned is that it confirms that the 'earth' one is using for testing is an 'effective' one.

[ ** I do have a 'testing lamp' which I made up many years ago, but haven't used for ages. It has an incandescent primary bulb, but also a couple of LEDs. ]

Kind Regards, John

 

[ban-all-sheds]

If one 'proves' the tester (which I usually do on the circuit concerned), isolates, and then finds that the tester 'proves' dead, it would seem incredibly improbable that the tester will have failed during those few seconds (unless it is a single-bulb 'testing lamp'**). I must confess that, as a last stage, I often do, as a final step, apply a neon screwdriver or suchlike, but that's more a matter of habit than anything else.

Last stage - turn the circuit back on and then off as a check that the tester hasn't failed.

 

[John D v2.0]

Non contact voltage detectors are handy just before you cut into a cable in the middle! Even if you're sure it's the right cable, a set of cutters is expensive!

 

[ban-all-sheds]

Handy as a way to check you've ID'd the cable.

NOT as a way to prove it's dead.

 

[John D v2.0]

Handy as a way to check you've ID'd the cable.

NOT as a way to prove it's dead.

Correct

 

[ban-all-sheds]

Why is cutting the wrong, dead, cable a concern re the price of side cutters?

 

[John D v2.0]

Why is cutting the wrong, dead, cable a concern re the price of side cutters?

Because of reasons you could never beginning to understand

 

[jg321]

Non contact voltage detectors are handy just before you cut into a cable in the middle! Even if you're sure it's the right cable, a set of cutters is expensive!

Unless it's a 3C+E you happen to be cutting, which in my experience will be picking up a voltage from anything within a 50 mile radius!

 

[ban-all-sheds]

Because of reasons you could never beginning to understand

What I understand is that you agree the non-contact detector is to help with cable ID, not to test for dead, therefore you agree that it would not be used to check for dead.

Therefore you'll use another way to test for dead, and the non-contact tester will not be doing anything to save your cutters.

What I understand is that you are again playing stupid games here. Whether you genuinely think that it benefits the forum, or whether you don't give a toss just so long as it gives you a childish giggle, I don't know.

 

[JDLDIY]

Right, I'm just getting back to this issue I'm having with these blasted Fluorescent fittings, other stuff cropped up which meant I had to put it on hold......

These lights worked for years, so I wouldn't think there's a polarity issue, or an error in the wiring. Indeed the one fitting which is still working is the furthest from away on the circuit. But that's not to say something hasn't developed somehow with the wiring and I'll check it all out.

Could I just get some general comments with regards to these electronic ballasts? Are they prone to suddenly going wrong? Is it best to purchase fittings with the older style removable starters?

Also, having checked over the wiring (I do have a proper tester which I will use following your instructions), how do I test the ballasts i.e. what readings should I get from them and how?

Oh, yes, from a safety perspective I'm aware I can't just turn the switch off - the garage has a modern style consumer unit so I can and will fully isolate the circuit when necessary.

 

[mwatsonxx]

Why is cutting the wrong, dead, cable a concern re the price of side cutters?

Lack of experience