Anyone ever had a false positive testing for dead with...

[Alarm]

On many multimeter's the 10A socket isn't fused at all. Yeah it's not a socket you use very often but even so you could still plug into it by accident. Even on ranges that are fused the fuses in cheap multimeter's are often only glass cartridge fuses.

If you are going to be using a multimeter for mains installation work at least make sure you get a set of approved fused test leads for it.

If you are putting your leads into that (10 amp) to test for anything apart from current then your not competent.
I check with that setting on a regular basis anyway, so not an error I am going to make.

As above it does not say anywhere YOU MUST NOT, it suggests another method of testing. Now I agree if your employer or indeed if it is in your own ISO or other manual then you work to that method.
Most decent meters have fused probes and a display saying what sockets to use on the equipment, same as for instance the Metrel Continuity and insulation testers. Also the meter carries two internal fuses. No display = check meter, easy really.
I use either and sometimes both my meter and combi when testing. Both before and after as you never know.
I have been caught out once, my own fault for not check, test check test procedure.

As before if it is in your work method statement then use the two probe method, if not use what is safe and TESTED. And double check.

 

[Alarm]

Here is a quote from a current thread,

Go and buy a multimeter.

 

[JohnW2]

What if the circuit you were isolating had DC in it, a multimeter set to AC would register zero.

I don't think it would, actually (well, none of the meters I've seen would) - but what if it did? If one 'proves' one's device on the circuit in question before isolating it, the scenario you're hypothesising would not present a problem or hazard.

Don't get me wrong. I'm not actually advocating the routine use of a multimeter for this purpose, and I wouldn't use one myself for this purpose if a more 'dedicated' instrument was near to hand. What I am doing is saying that the 'thou shalt not ever use a multimeter' view does not have much of a rational basis and, as I wrote last night, is not even what the HSE guidance says.

Kind Regards, John.

 

[JohnW2]

On many multimeters the 10A socket isn't fused at all. Yeah it's not a socket you use very often but even so you could still plug into it by accident.

Of course you could - human error is always possible. However, if you did that, the primary hazard would be to yourself, and would be exactly the same whatever you were using the meter for - it's not a specific reason for not using a multimeter for 'testing for dead'. It certainly wouldn't mislead you into thinking that a live circuit was dead, provided you did the pre- and post-test proving - and if you don't do that, you would be just as potentially incompetent/dangerous if you used a 'proper' test lamp or 2-pole voltage indicator.

Kind Regards, John.

 

[ban-all-sheds]

Never tried it, but I think I can say (and all here would agree) that connecting a MM on a 10A current setting between L & N or L & E on a live circuit would certainly not mislead you into thinking that it was dead.

Particularly if the meter and leads were unfused.

 

[ban-all-sheds]

 

[JohnW2]

Never tried it, but I think I can say (and all here would agree) that connecting a MM on a 10A current setting between L & N or L & E on a live circuit would certainly not mislead you into thinking that it was dead.

Exactly - and that could happen just as much if one's intent was to measure voltage as if one was 'testing for dead'. It's a consequence of incompetent/careless use of the instrument, regardless of the purpose for which it's being used. However, as we agree, it would not produce 'false reassurance' in terms of 'testing for dead'

Kind Regards, John.

 

[Alarm]

LOL @ the video, was awaiting its appearance.
Note how it is a fully calibrated fused probe fused unit thats cost at least £100.00

 

[bhm1712]

loving the video!

 

[Spark123]

What if the circuit you were isolating had DC in it, a multimeter set to AC would register zero.

I don't think it would, actually (well, none of the meters I've seen would) - but what if it did? If one 'proves' one's device on the circuit in question before isolating it, the scenario you're hypothesising would not present a problem or hazard.

Not having your meter set to the correct setting would definately pose a risk. There is absolutely nothing to say you must test the circuit live first prior to isolating.
A Multimeter set to AC volts will only register AC volts, not DC. If anything all you would register is the ripple (which is handy for seeing if your capacitors in a PSU are failing).
Similar vice versa, a DC instrument wont measure AC.

 

[Alarm]

A Multimeter set to AC volts will only register AC volts, not DC. If anything all you would register is the ripple (which is handy for seeing if your capacitors in a PSU are failing).
Similar vice versa, a DC instrument wont measure AC.

So when was the last time you got DC on a AC circuit?
But I have seen a lot, AC induction on DC.

 

[JohnW2]

A Multimeter set to AC volts will only register AC volts, not DC. If anything all you would register is the ripple (which is handy for seeing if your capacitors in a PSU are failing).

With respect, that's actually rubbish, at least in terms of every multimeter I've ever seen. The only thing you have to watch is that with very cheap meters (which have just a single diode for rectifying AC), they will only respond to DC on an AC range if it is connected with the correct polarity. However, any meter costing sensible money will have a bridge rectifier, and so will respond to DC on an AC range regardless of which way around it's connected. Try it!

If you want to measure ripple on a DC voltage with an multimeter, you would need to put a large, unpolarised, capacitor between the test voltage and your meter on its AC range (or use a 'scope!).

Similar vice versa, a DC instrument wont measure AC.

That is true, which is why one should prove the meter (which a source of known 230V AC) before testing.

Anyway, as others have asked, what on earth is this DC you think you might find in a domestic AC power installation?

Kind Regards, John.

 

[bhm1712]

Jumping in here....

I have had DC on an AC circuit due to a faulty DC drive card for a motor. However this was in a factory not a house! I couldnt understand it at first! my martindale was showing volts and yet my meter was showing 0 volts AC! if i hadnt have used my voltage indicator i could have subjected myself to 280VDC!!!

Edit: My eX rated meter does not respond to AC on a DC range nor vice versa and it was not cheap!

 

[bhm1712]

awesome: http://www.youtube.com/watch?v=lg44zuxGmMg&NR=1

dont buy cheap meters!

 

[Alarm]

As one says, what voltage was pumped through it?