When electrics go wrong!!!

[RenatSha]

There was a poor connection in this outlet. The clamps in the outlet are loose. The contact has warmed up and the socket has melted!

 

[RenatSha]

I agree! The circuit breaker requires maintenance every three months on schedule! The contacts must be tightened during servicing. Nobody did it.

 

[Simon47]

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.

 

[nicebutdim]

Might still have one of those welders - must check...

 

[brianmoooore]

Might still have one of those welders - must check...

I have one and have used it in the last week. Was doing some repairs to my Ifor Williams trailer and the gas ran out on the MIG, so had to dig out the old faithful.

 

[Simon47]

As I recall they were great welders - could wind them up to 180A. I recall sticking an old carbon brush in the electrode holder and using the arc to cut stuff up.

 

[SparkySy]

They were a bullet proof welder! I learned to run beads on one that my dad still has when I was about 9 years old (ahem 1987?)! Them and the old Oxford units, still plenty about in operation today testament to how good they were/are!

 

[DPG]

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.

 

[Simon47]

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.

 

[nicebutdim]

Member in question is in Islamabad, where it seems overloading is more common than in the UK.