Voltage testers - a basic question

[TheJack]

Hi. As part of safe isolation we use a voltage tester to prove dead; I've been taught that this is done by putting the probes in the following combinations: N+L, N+E, E+L.

But why check anything apart from the Live? That's where the voltage is coming from right?

 

[TheJack]

THANK YOU one and all.

I do struggle with the theory side of my learning as science has never come naturally to me, but I feel I understand this one now so I'm very grateful, cheers.

 

[Marvo]

I always do a live test before to ensure that there actually is an L N E.

That's also the way I do it, I prove the integrity of the circuit first before proving the state of the supply on it but I didn't want to suggest it in case that's not the way they teach it nowadays.

 

[westward10]

Generally taught earth to line, keep probe on earth then earth to neutral then keep probe on neutral and neutral to line. Same principle for single or three phase. You wouldn't be criticised if you didn't do this providing all sequences are done but getting a method in your head will help. It is acceptable to use the last test, line to neutral to verify operation of the instrument but tell your tutor.

 

[pirate]

When asked a similar question I always refer to this John Ward video:

View: https://www.youtube.com/watch?v=-qh28sHs7XA


If you are not at the CU, a proving unit is essential.
Why some folks baulk at the price is a mystery to me...die and leave partner and kids behind?

OK, we all do the plug-in tester, switch the mcb or rcbo off, wave a non-contact tester over the socket or whatever, and carry on...but proper testing, test the 2 pole tester before, do the test, test it again...it just makes sense.
Also good advice...do not take anyone else's word that a circuit is dead...always do your own checks.

 

[James]

Also good advice...do not take anyone else's word that a circuit is dead...always do your own checks.

Good advice,
not doing the above has cost me a pair of nearly new cutters in the past, cant remember if a new pair of underpants was required but it is an altogether unpleasant experience (at best) and of course in some cases it may be fatal.

trust me, the flash and bang not only tells you that you have messed up but also anyone who is near. it will cause any customer you may have to be somewhat concerned about your level of competence as an electrician.

therefore if you are lucky enough to come away with no physical injury, you are more than likely going to get some sort of financial penalty as people no longer see you as a professional.

 

[mainline]

THANK YOU one and all.

I do struggle with the theory side of my learning as science has never come naturally to me, but I feel I understand this one now so I'm very grateful, cheers.

One thing that maybe is worth a mention is to always put the probe on E or N first as depending on the impedance of the instrument, once you connect the probe to L the other end of the probe will become L If you are touching earth and touch the N probe at the same time you can get a shock.