Bang!

[Delboybully]

So I go to a job a couple of days ago in a small shop. One of the things to do is fix an RCD that isnt working in a dual RCD board (not that neat but ok, no labels), everything works but if you turn the RCD off it doesnt disconnect the supply to the 4 MCBs it covers. Also the test button doesnt work. Take the cover off the board and the RCD isnt bypassed, it looks like it has failed closed.

I do a quick Ze, turn off the MCBs, RCDs and the main switch, test for dead and replace the RCD. I then power up and the replacement RCD trips. So I then start doing combined IR test L+N to E for each circuit to find the offending circuit. MCBs 1,2 and 3 or ok

Which leaves circuit 4, I connect my jump lead to neutral and the live and BANG!!!!! Nice pirotechnics with a few bits of hot metal spraying around!
Luckily my jump leads have a plastic covering on them or I could have got a belt!

I can tell you I wasnt expecting that. Luckily my jump leads have a plastic covering on them or I would have got a belt! My apprentice missed the fireworks as he was getting stuff from the van but he was impressed with the jump lead afterwards with a bit missing and the charring on the live cable

So I do some more investigating and it turns out the cable coming into the MCB was live and coming from the upstairs flat and was feeding the other 3 circuits in the shop through the bus bar. The guy in the flat above (luckily he was in) told me he has been getting electric bills of roughly a grand every 3 months, no wonder he had been paying for half the electric bill for a small cafe.

Now I followed the safe isolation procedure as I always do but this still happened. I phoned the Elecsa technical helpline and the guy said you followed the safe isolation procedure and its just one of those things you occasional see. He suggested waving a volt stick around the board in future. I then needed to phone the technical helpline again today on another matter so I asked the new guy the same thing, he again said that there isnt much you can do about these things.

I am one of the hated 5WWs, been doing this for approx 2.5 years. I am prepared for a slating, however I would be interested to learn how any of you would of approached this problem and would you of ended up in my situation. Obviously I followed the correct isolation procedure but still ended up in an undesirable spot. Any suggestions would be appreciated

Del

 

[ipf]

Love the sparkler description itselectric.

- - - Updated - - -

So even pyro has its limits!

Nothing better than a bit of 'pyrotechnics' to liven thing up a bit.

 

[Knobhead]

and why not? I do!
(went to change a 250 hp 3 phase motor one time and identified and locked out the disconnect, only to find out it was fed from two different panels after metering the leads)
have been careful to check everything since then!

So two feeds to one motor, not uncommon for critical equipment. Interlocked isolators or change over switches not drifted over the pond yet?

We’ve had them for many years. OK you’re of a young nation, still time to learn.

 

[mayfair]

Stop being prat and take that chip off your shoulder

I suggest you read up on safe isolation proceedures before you hurt yourself or another.
What were you doing working in a commercial environment?
Do you consider yourself suitable to train, and keep safe, an apprentice?

Boydy

 

[Badged01]

Stop being prat and take that chip off your shoulder

But who have the "chip" on their shoulders ...... the old knowledgeable sweats pontificating in their glories or the youngsters wanting to learn and make a way in the trade?!?!

 

[Badged01]

p.s. whilst I do consider myself old, I dont consider myself knowledgeable or trying to make a way in the trade! Im just a contankerous git who enjoys a bit of healthy banter ......

 

[mayfair]

None of us should have a chip , your never to old to learn and i remember when i was a young lad some of the old qualified guys were always willing to help. This forum should be all about help and advice. The atitude of some members stinks IMO.

But who have the "chip" on their shoulders ...... the old knowledgeable sweats pontificating in their glories or the youngsters wanting to learn and make a way in the trade?!?!

 

[guest119]

There is a big difference M.
You are talking of an older tradesman helping a younger one or an apprentice, which (I know you wont believe me :biggrin5: ) I do willingly on a regular basis.
However this situation is very different.

Buenos Noches

Boydy

 

[gnuuser]

So two feeds to one motor, not uncommon for critical equipment. Interlocked isolators or change over switches not drifted over the pond yet?

We’ve had them for many years. OK you’re of a young nation, still time to learn.

no interlock present or transfer switch on that motor
it was shere dumb luck the guys who wired it before didnt end up with a phase to phase short in the switchgear

we do have multi feed motors here but they were wired properly with interlocks

 

[GLENNSPARK]

So I go to a job a couple of days ago in a small shop. One of the things to do is fix an RCD that isnt working in a dual RCD board (not that neat but ok, no labels), everything works but if you turn the RCD off it doesnt disconnect the supply to the 4 MCBs it covers. Also the test button doesnt work. Take the cover off the board and the RCD isnt bypassed, it looks like it has failed closed.

I do a quick Ze, turn off the MCBs, RCDs and the main switch, test for dead and replace the RCD. I then power up and the replacement RCD trips. So I then start doing combined IR test L+N to E for each circuit to find the offending circuit. MCBs 1,2 and 3 or ok

Which leaves circuit 4, I connect my jump lead to neutral and the live and BANG!!!!! Nice pirotechnics with a few bits of hot metal spraying around!
Luckily my jump leads have a plastic covering on them or I could have got a belt!

I can tell you I wasnt expecting that. Luckily my jump leads have a plastic covering on them or I would have got a belt! My apprentice missed the fireworks as he was getting stuff from the van but he was impressed with the jump lead afterwards with a bit missing and the charring on the live cable

So I do some more investigating and it turns out the cable coming into the MCB was live and coming from the upstairs flat and was feeding the other 3 circuits in the shop through the bus bar. The guy in the flat above (luckily he was in) told me he has been getting electric bills of roughly a grand every 3 months, no wonder he had been paying for half the electric bill for a small cafe.

Now I followed the safe isolation procedure as I always do but this still happened. I phoned the Elecsa technical helpline and the guy said you followed the safe isolation procedure and its just one of those things you occasional see. He suggested waving a volt stick around the board in future. I then needed to phone the technical helpline again today on another matter so I asked the new guy the same thing, he again said that there isnt much you can do about these things.

I am one of the hated 5WWs, been doing this for approx 2.5 years. I am prepared for a slating, however I would be interested to learn how any of you would of approached this problem and would you of ended up in my situation. Obviously I followed the correct isolation procedure but still ended up in an undesirable spot. Any suggestions would be appreciated

Del

he did what?..

actually i`m shocked by this...

 

[micknew]

Would of saved his life even if they are frowned upon.
They save time if the operator understands their limitations and knows how to use them.
Seems to be in 'vogue' to slag them off, anyway Pink Floyd on Sky 116.

 

[HandySparks]

he did what?..

actually i`m shocked by this...

I agree with telectrix, a wave with a volt stick isn't a bad idea as a second check that you've not missed finding a live conductor somewhere. In fact, if you're just about to cut into a cable (away from a directly testable termination point), it's really the only way to check that it's not live after you've been through the proper isolation procedure.

 

[Marvo]

I think the problem with them is that they're widely abused and misused by people out of laziness and ignorance. I have one I use occasionally but I banned my guys from using them (and neon screwdrivers) or even taking them on to site because they just can't stop themselves misusing them.

 

[MDJ]

Would of saved his life even if they are frowned upon.
They save time if the operator understands their limitations and knows how to use them.
Seems to be in 'vogue' to slag them off, anyway Pink Floyd on Sky 116.

if it worked, I have always said if you are stupid enough to use a volt stick then tape 2 together, if one packs up the other may work, appalling DIYers kit, whats wrong with using a IR tester after removing all lamps and turning switches on, removing all plugged in appliances and testing with 500 volts across each phase/live conductor and neutral then each phase and earth then each neutral and earth providing all breakers and the main switch is off? doing it this way, the correct way will avoid what happened, end of, just get a grip all of you, this is now turning into fred carney's circus.

 

[GLENNSPARK]

Would of saved his life even if they are frowned upon.
They save time if the operator understands their limitations and knows how to use them.
Seems to be in 'vogue' to slag them off, anyway Pink Floyd on Sky 116.

its the fact that a so called `technical helpline` could advocate just waving a volt alert about off the cuff....when the tool of choice would/should be the AVI together with a known source of supply...such as a proving unit...

 

[GLENNSPARK]

I think the problem with them is that they're widely abused and misused by people out of laziness and ignorance. I have one I use occasionally but I banned my guys from using them (and neon screwdrivers) or even taking them on to site because they just can't stop themselves misusing them.

Marvo...i have one as well....but i certainly dont use it for `safe isolation`...caus it aint....

and its only used with discression