Voltage Tester Recommendations

[aesmith]

Hi,

At the moment the only way I can test for presence/absence of voltage is to use my Fluke multimeter and take a measurement. I must admit I do not particularly like touching a live or possibly live contact with the probe, even though I know fine that they're supposed to be safe even for significantly higher voltages.

On other threads I've seen references to specific testers to check voltages. Would these do anything that the Fluke doesn't do? In particular I saw on one thread the poster used something like this .. Volt Alert. How well do these work? It seems appealing that it doesn't require contact with the live terminal.

Thanks, Tony S

 

[ricicle]

Voltage sticks are ok as a guide for finding live cables, they cannot be used to prove dead. That can only be done with an approved two probe voltage tester (preferably along with a proving unit)

Multimeters are not the correct way either due to the fact that they can be incorrectly set.

 

[bernardgreen]

They "measure" ( detect ) the difference in voltage between the hand that is holding them and the conductor they are touching ( or very close to ).

If you are standing very close to a live wire ( such as the cable dropping to a switch) then touching on of these on an earthed item can make it glow.

Worse is that touching it on a live wire may not make it glow. Standing close to a live wire can, bay capacitive coupling, raise the potential of you body close to mains voltage, ( akin to static electricity ). There is no danger as the capacity is extremely small so the current is too small to have any effect.

The only safe way to test for voltage ( and no voltage ) is a two point tester

 

[Iggifer]

The Fluke T150 is a great 2 pole tester, it defaults to voltage and will even indicate voltage with discharged batteries. It has a fixed probe that gets broken easily though

The Fluke T5-1000 is a much better design, but you still have to select what you want to measure

 

[aesmith]

OK thanks. Voltage stick doesn't sound much use.

It sounds like I'm better off sticking with the Fluke. Could you elaborate on the caution "Multimeters are not the correct way either due to the fact that they can be incorrectly set". Do you just mean I need to make sure it's switched to ACV, or is there some more subtle risk?

Tony S

 

[Iggifer]

Yea you can create a big bang if you connect it to a live circuit on the wrong setting. They only have a little fuse in them

 

[ricicle]

Or you can have them on the wrong setting and they won't register anything.

 

[JohnW2]

Yea you can create a big bang if you connect it to a live circuit on the wrong setting. They only have a little fuse in them

Whilst that is true, it is true of any use of a multimeter (or, indeed, any sort of meter with switchable functions, unless it has suitable built in protective measures). The more specific problem of using a multimeter to 'test for dead' is that (as ricicle has said), if set to the wrong range, it could fail to detect the presence of a voltage. Mind you, even 'approved 2-pole voltage testers' (or lamps) have been known to malfunction (hence not detect the presence of a voltage) - which is why they should be 'proved' both before and after 'testing for dead'.

Kind Regards, John

 

[aesmith]

Thanks. I'm quite happy about setting the meter to the correct setting, you have to have some self-reliance. In general I'm very comfortable using the meter and know how to use it's different functions. It's just that most of the time I've been using it on lower voltages, so I'm a little cautious when working with 240V, maybe unnecessarily.

By the way, the "big bang" and "little fuse" points sound contradictory. Surely you can only make a little bang when blowing a 300mA fuse? To do that I'd need to have the meter set to either AC or DC current, and have the +ve lead in a different socket. I'm not going to try that to see how big a bang it makes. I'm not sure what would happen if the meter was incorrectly set to continuity or resistance, which uses the leads in the same sockets. I'm not going to try that either.

I take the point about wrong setting meaning it gives an incorrect zero reading. I suppose it would be good practice to check the live circuit before disconnection, as well as after.

 

[PrenticeBoyofDerry]

Are you wanting a meter that gives a measured voltage, or one that indicates that a voltage is present?

 

[Adam_151]

Does your fluke multimeter have GS38 probe tips?

 

[Monkeh]

Yea you can create a big bang if you connect it to a live circuit on the wrong setting. They only have a little fuse in them

Mine have fuses rated for 1000V 50kA, I don't know about yours... Send me £5 to replace one and I'll make a little bang for you.

By the way, the "big bang" and "little fuse" points sound contradictory. Surely you can only make a little bang when blowing a 300mA fuse? To do that I'd need to have the meter set to either AC or DC current, and have the +ve lead in a different socket. I'm not going to try that to see how big a bang it makes.

An improper fuse on a circuit with a very high rated breaker or fuse (ie. before your MCBs) may fail to interrupt the current. This would have fatal effects on the multimeter, and rather bad ones on your hand. There are also other concerns with very high energy circuits (an inappropriate and inappropriately used multimeter caused an arc between unprotected phases, resulting in the death of the operator and significant damage to the building, in one notable incident).

I'm not sure what would happen if the meter was incorrectly set to continuity or resistance, which uses the leads in the same sockets. I'm not going to try that either.

Absolutely nothing, on a proper meter. Magic smoke release on a toy.

 

[Iggifer]

Mine have fuses rated for 1000V 50kA, I don't know about yours... Send me £5 to replace one and I'll make a little bang for you

My friend lent his megger to a colleague recently, when he got it back he (foolishly I know, but these things happen) went to IR test an energised circuit, when his meter stopped working he went to replace the fuse, only to find his 'friend' had replaced his 500mA megger fuse with a BS1362 13A fuse goodbye megger

 

[Monkeh]

Mine have fuses rated for 1000V 50kA, I don't know about yours... Send me £5 to replace one and I'll make a little bang for you

My friend lent his megger to a colleague recently, when he got it back he (foolishly I know, but these things happen) went to IR test an energised circuit, when his meter stopped working he went to replace the fuse, only to find his 'friend' had replaced his 500mA megger fuse with a BS1362 13A fuse goodbye megger

Ahh, that magic smoke smell.

 

[aesmith]

Does your fluke multimeter have GS38 probe tips?

I don't know, they are the probes that came with it (Fluke 75). Recommendations on better/safer probes would be much appreciated. I keep meaning to get a better set of test leads for electronic and low voltage work in any case.