Electric Shock - Never should happen, or occupational hazard?

[rj1984]

Hello, My name is rob, new here but I have a burning question,

So, I work as an Electrical/Electronic technician at a University. I'm not a AM2 qualified typical domestic/industrial spark but have Level 3 Installations diploma and a few years experience "on the job". I would say that Electrical wiring up and fault finding of machines takes up only about 40% of my job. I am by no means, at the same level as an everyday domestic/commercial/industrial electrician. I mainly work with smaller DC Electronic circuits.

A few days ago at work, I got a shock from a charged Capacitor - either a P.F correction or start/run from 1ph 230 volt Motor. The current came back down to a 13 amp plug top connected to this Lab sample shaker machine, that I was holding. It did not hurt but it was disturbing as it was strange sensation and contracted my tricep in a way I could never do by trying. I threw the Plug top down quickly. My boss didnt seem concerned and I'm sure a person could have much severe a shock.

However, now I am worried about the long term effects of this, as I have read that studies have linked progressive neurological diseases to electric shock. This is causing me quite a bit of anxiety.
I thought to myself though, that with the 1000s of Electricians in the UK alone, surely there would be more concrete evidence of these effects in the long term and practicing electricians may likely experience many shocks over there career?

still I cant shake it from my head.

So, really my question is do you guys who are busy everyday electricians - do you have many shocks over a period of time, and just take it as a risk of the Job. Or is it something that happens rarely, if ever to a practicing Electrician.?

Does the shock that I had sound mild or typical? - I have never had a 230/400 v belt.

Thanks for reading and hope someone will reply.

 

[kerching]

In m opinion a capacitive load should not be connected via a plug for this very reason You have only received a 'crack or a 'tickle,
Shocks come in various levels
Crack/tickle
Pisser
Jolt/belt
A Right Worker
Dead

 

[Andy™]

So, really my question is do you guys who are busy everyday electricians - do you have many shocks over a period of time, and just take it as a risk of the Job. Or is it something that happens rarely, if ever to a practicing Electrician.?

don't touch any wiring that you haven't tested and proven dead. lock out supplies etc. do the job properly and you shouldn't be getting any shocks

 

[rj1984]

In m opinion a capacitive load should not be connected via a plug for this very reason You have only received a 'crack or a 'tickle,
Shocks come in various levels
Crack/tickle
Pisser
Jolt/belt
A Right Worker
Dead

Thanks

 

[rj1984]

don't touch any wiring that you haven't tested and proven dead. lock out supplies etc. do the job properly and you shouldn't be getting any shocks

Thanks

 

[Geoff1946]

I would suspect that there may be a fault with the device you were using. I believe any capacitor in portable gear should have a bleed resistor to ensure its discharge within a few seconds.
You may have defeated this if you picked up the equipment in one hand and simultaneously unplugged it and grabbed the pins.
As others have said, the aim is to never experience any shock, but I would doubt the honesty of any electrician who claims never to have experienced one!
A really good tip, (in my opinion) is to keep one hand behind your back if touching anything! In that way you cannot get a shock current across your chest, which is the most dangerous.

 

[poni]

busy everyday electricians - do you have many shocks over a period of time, and just take it as a risk of the Job. Or is it something that happens rarely, if ever to a practicing Electrician.?

us busy everyday electricians,( I like that) should not be getting shocks(unless its a tax bill) as we all practice LOTO, don't we? as the old saying goes, don't stick your finger where you wouldn't stick your ....(I have forgot how that ends)
but I do know you don't forget you first

 

[rj1984]

I would suspect that there may be a fault with the device you were using. I believe any capacitor in portable gear should have a bleed resistor to ensure its discharge within a few seconds.
You may have defeated this if you picked up the equipment in one hand and simultaneously unplugged it and grabbed the pins.
As others have said, the aim is to never experience any shock, but I would doubt the honesty of any electrician who claims never to have experienced one!
A really good tip, (in my opinion) is to keep one hand behind your back if touching anything! In that way you cannot get a shock current across your chest, which is the most dangerous.

That's exactly what happened (unplugged the device) touched the pins. Further investigation seems necessary. Thanks.

 

[rj1984]

us busy everyday electricians,( I like that) should not be getting shocks(unless its a tax bill) as we all practice LOTO, don't we? as the old saying goes, don't stick your finger where you wouldn't stick your ....(I have forgot how that ends)
but I do know you don't forget you first

Cheers

 

[kerching]

In over 50 years in the trade ( hate it when people refer to it as a 'game' ) I don’t think I have had more than a dozen 'episodes'. Nothing bad apart from one. When I was an apprentice cutting out some scrap under a floor

 

[SPECIAL LOCATION]

Anyone with a reasonable level of electrical qualifications, and more than a couple of years of practical hands on experience working on real world installations.... Should have figured out the essential basic rules of working safely on any electrical equipment..

e.g. Assume every accessory/wire/exposed conductive part/etc.. is incorrectly wired, still live, dangerous, faulty.. And that ALL circuit descriptions at distribution boards/consumer units are wrong... Until you have proved otherwise with appropriate test equipment, and isolated all sources of supply and/or any discharged any potential sources of hazardous electrical energy.
So any shocks should be very few and far between!!

But that said.. The old "Borrowed/Shared" neutral can still occasionally catch you out..
Even when the circuit you are working on is all nicely isolated..
But some git has used your neutral as the return for a live supply via a different MCB!!

 

[binky]

capacitors store electrical charge, so items with such devices fitted are bset shut down ( ie siwtched off) and left for around 5 mins to fully discharge the capacitors. As for any medical effects, you are over worrying. Getting a shock is quite normal for electirans ( it shouldn't be but...), so most of the members on here would be dead years ago if there was a real health problem, although there is evidence of detrimental health affects for those who work with HV on a long term basis.

 

[kerching]

Best piece of advice I was given,…."always treat it as live even when you know it’s dead as one day it won’t be, and burning flesh smells horrible "

 

[rj1984]

capacitors store electrical charge, so items with such devices fitted are bset shut down ( ie siwtched off) and left for around 5 mins to fully discharge the capacitors. As for any medical effects, you are over worrying. Getting a shock is quite normal for electirans ( it shouldn't be but...), so most of the members on here would be dead years ago if there was a real health problem, although there is evidence of detrimental health affects for those who work with HV on a long term basis.

Thanks

 

[Radiotowers]

Hi Rob,
as mentioned above there should be a bleed resistor in parallel with the capacitor, this should be a high value perhaps a few Megohms to slowly discharge the cap ( just a few milliamps drain) without affecting the circuit it feeds. The instantaneous peak voltage of a 230 v Rms supply is around 340 volts and that is what the capacitor will be rated for, if by pure chance you disconnect the supply at the right moment that capacitor will hold 340 volts and by shorting across this you received a DC shock. However the equipment should never be able to shock you . As far as receiving a shock , pretty sure every spark has had a few knuckle cracks and all preventable.

 

[rj1984]

Hi Rob,
as mentioned above there should be a bleed resistor in parallel with the capacitor, this should be a high value perhaps a few Megohms to slowly discharge the cap ( just a few milliamps drain) without affecting the circuit it feeds. The instantaneous peak voltage of a 230 v Rms supply is around 340 volts and that is what the capacitor will be rated for, if by pure chance you disconnect the supply at the right moment that capacitor will hold 340 volts and by shorting across this you received a DC shock. However the equipment should never be able to shock you . As far as receiving a shock , pretty sure every spark has had a few knuckle cracks and all preventable.

Cheers radiotowers, and thanks everyone for the replies. I feel better now.
I reported this to my line manager this morning and also to the health and safety department. I suspect that this machine has been designed by another member of staff way before my time, albeit badly. We are now going to modify it so this cannot happen again. Either with a dol or just a contactor, with the machines timer in the coil. It was an 8uf cap inside the motor housing where the connectors are . There are a few different ratings on the can all over 230v. The cap is for starting the motor.

 

[rj1984]

Cheers radiotowers, and thanks everyone for the replies. I feel better now.
I reported this to my line manager this morning and also to the health and safety department. I suspect that this machine has been designed by another member of staff way before my time, albeit badly. We are now going to modify it so this cannot happen again. Either with a dol or just a contactor, with the machines timer in the coil. It was an 8uf cap inside the motor housing where the connectors are . There are a few different ratings on the can all over 230v. The cap is for starting the motor.

Also with the bleed resistor. I mentioned this to my boss. He reckons the motor cools should drain it. Not sure about that.

 

[Andy™]

motor caps would usually discharge through the motor windings

 

[mort2376]

At least no one has said "Thats never happened to me" !

We all know that we should never work live, but we still occasionally do it, out of wanting to get the job done, sheer laziness, or plain old CBA !

My question is when its live and you know its live and you get a belt why does it never seem as bad as when you think its dead and you get a belt ???

There was a slide at the recent CEF tech talk about safe isolation and only about 20% of electricians actually use a lock off device. ( Thats a proper one with a padlock not tape over the mcb ! )

It is frightening that we all know the dangers, but seem quite happy to take risks with our one and only life.

Worst one I had was an an apprentice rewiring a local restaurant. Stripping out 3rd floor all boards were dead and only temporary supplies in the building. Undid a socket unscrewed the cables and grabbed them to pull tight to cut them and was thrown across the room. Socket was fed from the next door building ! had been for years and no one knew.

 

[rj1984]

At least no one has said "Thats never happened to me" !

We all know that we should never work live, but we still occasionally do it, out of wanting to get the job done, sheer laziness, or plain old CBA !

My question is when its live and you know its live and you get a belt why does it never seem as bad as when you think its dead and you get a belt ???

There was a slide at the recent CEF tech talk about safe isolation and only about 20% of electricians actually use a lock off device. ( Thats a proper one with a padlock not tape over the mcb ! )

It is frightening that we all know the dangers, but seem quite happy to take risks with our one and only life.

Worst one I had was an an apprentice rewiring a local restaurant. Stripping out 3rd floor all boards were dead and only temporary supplies in the building. Undid a socket unscrewed the cables and grabbed them to pull tight to cut them and was thrown across the room. Socket was fed from the next door building ! had been for years and no one knew.

Jeepers! Makes mine sound so mild.
The machine was off and isolated from mains. I have opened plenty of amps, TVs and other equipment containing large caps and known to stay well away and drain out with device isolated from mains. I guess I didn't expect it from a motor. Will do now! lesson truely learned!