Bang! Large flash / bang at voltmeter tips.

[Tasty]

Hi all,

Just had quite a fright & must say I'm pretty annoyed with myself.

I've just tested the ends of a wire to check if it was live (using a fluke voltmeter) and had a massive flash and bang at the points of the probes). I'm annoyed because I should have isolated the circuit and terminated the wire in a block rather than testing wire as it was found (it was left as you'd find twin and earth if had just been cut, not stripped).

Could you guys help me with what the bang was so I can learn properly from this mistake? (I'd have said it was the very loose contact I had between probes and wires but I'd appreciate any thoughts and correction on this). The rcd and mcb blew but everything seems ok now. I've isolated the wire at the switched fused spur unit the cable leads to & will fully isolate before terminating the wire properly now.

Thanks in advance,

Stu

 

[davelerave]

L-E short circuit

 

[telectrix]

shorted out with your probes

 

[ian.settle1]

L-E short circuit

Or L-N short circuit or possibly shorted all 3 together if not stripped back

 

[Marvo]

Testing into the end of a cleanly cut cable isn't safe, the wires are too close together and can be easily shorted by a meter probe. The fright is all part of the learning curve, it helps you remember in future to isolate all the power if necessary, strip the cable back and put it in a connector block so you can then identify the circuit. Luckily you're still around to tell the tale and hopefully it's just cost you a set of tester probes and no more.

 

[Tasty]

Thanks all, so would I be correct in thinking that properly terminating the wire in a terminal block whilst dead would have stopped this happening?

Cheers

 

[Marvo]

That's about the size of it.

 

[Tasty]

oops, just read the post before, thanks for that - yeah, I feel very lucky and will definitely take a lot more care in future before doing this, being in a rush was no excuse.

Much appreciated guys!

 

[telectrix]

as long as you don't set the meter on AMPS !!!

 

[davelerave]

Or L-N short circuit or possibly shorted all 3 together if not stripped back

ya maybe -he said rcd+mcb so i assumed L-E SC on a TN supply

mind you i've had a few cans so i do get confused

 

[Knobhead]

All I’ll say is it’s your own fault!
Try testing live at 11KV, no room for forgiveness what so ever!

 

[Tasty]

Next time I encounter a 11kv domestic supply i'll let you know how it goes.

Seriously though, you're right, I should have known better. Consider my wrist firmly slapped.

 

[RogertheBodger]

Enjoy the big green spots before the eyes, not that i've ever done it!
11kv eh must have been huge green spots.

 

[eskimo39]

If you look at your probe tips is there a little bit melted or blackened?? All you will have done is shorted between 2 of the wires causing a short circuit and the MCB blew due to overload, the RCD blowing as well sounds like one of the wires you shorted across was the earth. Bloody 11kv sounds frightening. I have seen splash from a colleague shorting across 2 phases at 400v and that was impressive (in a bad way).

 

[Tasty]

Yeah one probe is black and the live wire in the T&E had a little metal 'blob' on it.

In a way i'm glad i've experienced it now, it really hits home all the health & safety lessons when a fault happens right in front of you!