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When electrics go wrong!!!

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Darkwood

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Just setting up a new sticky thread that unlike the dodgy trade pics thread is focused on showing the result of failures in electrical installations IE - damage caused which may be due to various reasons. Please do not post pics of poor workmanship if there is nothing else to show like the consequences, use the dodgy pics thread for that.

I will start off below with an example. I am hoping the fresh faced members and inexperienced can get a visual incite of what to expect when you come across such things and how to understand what has occured.
 
That's always worked for me. Mention smoke, and they're on site within the hour.
Only had to call out the DNO once when <whistles innocently> I managed to blow the main fuse. As there was no smoke, I was told "within 3 hours". But they refused to take my number - why would they, after all I'm on site; but they did insist on getting the householder's number (which they checked against their records) - so of course they contacted the householder who was at work.
DNO said "our engineer attended but there was nobody there" - we replied "oh no he didn't". They did manage to get him to go back, and then it was "he's standing outside the front door" - "oh no he isn't !"
Yup, he was at the wrong address. It's one of those places where the address can be confusing if you omit part of it - like "5 Greenfield, Whitegate, Anytown"; he was stood outside 5 Whitegate.
I have never had to play with an electric welder (other than a hour or two training as a student) so I would assume the high current secondary is not earthed to avoid a direct burn-out of the welder's earth. Or is it?

So was it two metal objects linked via conduit/CPC, and the welder's clamp was on one and the electrode arcing to the other?
There are a number of possibilities.
There's a brand of oil filled welders (Pickhill Bantam*) that I recall as being popular with farmers - I recall we had one at a farm I worked on as a lad, and a friend's farm has one - which have bare windings sat in a metal box full of oil. Apparently, if mishandled badly enough, the windings can distort and touch the case or each other. Thinking back, I can recall doing some welding and finding the gate I was working on had a bit of a tingle to it - at least we were wearing rubber wellies ! No RCDs back then.
Some might have the secondary connected to the supply earth as a safety feature if there isn't considered sufficient isolation. Then if someone decides that a big metal table should be earthed (either as a safety feature or just because it's bolted to some structural steelwork) then you've an alternative path separate to the welder earth.

* Dunno why it was called Bantam - it certainly wasn't Bantam in weight, they're 'kin heavy b'stards.
 
Hello, I wanna say that one of the biggest causes of frequent circuit breaker tripping is the overloading of power boards. Most homes and apartments, even newer ones, don’t have enough power points to cater to, for example, a complete home entertainment unit setup. If circuit breakers in your home are tripping frequently, it could be down to circuit overload.

It does make sense that over-current protective devices can be tripped by excess current draw I suppose.
 
But considering a typical setup is one or more ring finals, fed by a 32A MCB - so capable of a continuous (almost) 8kW. Even the most extravagant home entertainment system isn't going to get near 1kW.
I doubt that many homes suffer from frequent over-current trips.
 
Customers spotlights stopped working.
 

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I realise these pictures aren't as spectacular as the others but they do show how powerful 230V can be. Plus it's a very real outcome if safe isolation isn't adhered to.

If a L-N or L-E short at 230v can take even a little chunk out of steel alloy, hardened with vanadium, then I hate to think what it would do to a persons hand/arm holding a pair of non VDE pliers.

These are my (now spare) side cutters after I cut through a live cable some years ago (whilst my mind was busy elsewhere, thinking about a difficult relationship with a gorgeous yet crazy woman.). We must keep our minds on the job!

View attachment 84131 View attachment 84132
I have a pair of those wire strippers.

They started life as a £45 PAIR OF Klein side cutters and lasted about an hour and forty-five minutes.

I bought them off a trade counter while I was picking up a length of MT2 to stick an extra socket in an office.

The existing trunking ran just below the ceiling so it was an easy case of pulling a leg out of one socket, dropping it into the new and running a new leg back to the old socket.

What could possibly go wrong?

So pulled out my virgin side cutters out to cut out a notch for the new drop and.....bang.

Yep there was a 1.5 laying flat in the bottom of the trunking that I didn't see on account of not being attentive enough to get my lazy arse up and have a look.

In fairness to myself it was the flattest piece of cable I've ever seen, or not in this case, in trunking. It's like the spark ironed it.

Lessons were learnt and new procedures were put in place.
 
I realise these pictures aren't as spectacular as the others but they do show how powerful 230V can be. Plus it's a very real outcome if safe isolation isn't adhered to.

If a L-N or L-E short at 230v can take even a little chunk out of steel alloy, hardened with vanadium, then I hate to think what it would do to a persons hand/arm holding a pair of non VDE pliers.

These are my (now spare) side cutters after I cut through a live cable some years ago (whilst my mind was busy elsewhere, thinking about a difficult relationship with a gorgeous yet crazy woman.). We must keep our minds on the job!

View attachment 84131 View attachment 84132
Most sparks have or have had cutters to compare, I’d wager.
Regarding the short circuit cutting with uninsulated tools, it’s not the same short circuit current via your body (load). Nasty and dangerous, I know, but it’s not going to blow a hole in you. The arc from the metal tool is a real problem, also.
 
I realise these pictures aren't as spectacular as the others but they do show how powerful 230V can be. Plus it's a very real outcome if safe isolation isn't adhered to.

If a L-N or L-E short at 230v can take even a little chunk out of steel alloy, hardened with vanadium, then I hate to think what it would do to a persons hand/arm holding a pair of non VDE pliers.

These are my (now spare) side cutters after I cut through a live cable some years ago (whilst my mind was busy elsewhere, thinking about a difficult relationship with a gorgeous yet crazy woman.). We must keep our minds on the job!

View attachment 84131 View attachment 84132
I'll wager that all the sparks here have converted side cutters to wire strippers!
Since I did my second ones I've kept a new pair in the bag hoping I'll never have to take them off the card!
 

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