explain this!

Bruthal

2011 wrote: »

No I am offering it as a possibility. I have seen fuses of all sizes fuses fail and I have also seen discrimination not work.
:

Ive seen you mention descrimination a few times, well ok, since you have told us the same current flows in a live and neutral in a live neutral fault, which believe it or not i had a fair idea of, i will give you my descrimination thoughts.

We expect a smaller fuse to blow before a bigger one. And you say you seen fuses of all sizes fail, is this unusual for a sparks? And where is descrimination coming into this? When descrimination does`t work, it would be reasonably assumed that several devices operate instead of the theoretical smallest one alone, but it would be quite unusual in my experience for a 63 amp one to go ahead of a 13 amp one, and the 13 amp one stays intact. So will you now say this is not unusual, because if you do say this is not unusual then i will be very susprised.

And if descrimination is not working because of a large fault current, yet again how did a 13 amp fuse survive,, do you not
see the obscurity about all this?? You dont seem to be.

And if the main fuse is so weakened that it is weaker than a 13amp one, then a large current wont get a chance to flow, so which is it? And if the main 63 amp fuse is weaker than 13amps, then in fact descriminatin did work, as the 63amp fuse is now maybe a 5amp fuse.

I dont know, my experiences must be very obscure or something,
Maybe you could give a good theory as to what happened in this case and then we can see. Im guessing you reckon a short occured in the transformer and blew a 95% weakened 63amp neozed fuse? It is a good theory.

But the RCBO was also damaged, so how did this happen. So tha traffo shorted?, the RCBO was ruined, the 63amp fuse blown, but the traffo plug fuse was fine, so tell us your idea of what happened, not just that a large short circuit current flowed and then correct someone`s points that gives a few ideas.

And go easy on my mistakes haha, its a discussion more than an arguement,

Bruthal

2011 wrote: »

``But no way can i ever see a 13 amp fuse survive a short circuit that blows a 63 amp fuse no matter what its condition``

No matter what the condition??? I would not agree. If the condition of a fuse is bad enough even vibrations can cause it to fail.

True, but a fuse failing from vibrations has not failed becaus of a short circuit. Dropping a fuse can weaken it, or extended periods at its limit etc, but be realistic, a short in a traffo blowing a 63 amp fuse and doing nothing to a 13amp plug fuse is extremely remote. If it does not raise an eyebrow then im very surprised even if it was a very weak 63 amp fuse.

Fuses can go with no virtually no load on them, no problem with that at all, there is a fair chance in a situation like this that a main fuse was faulty. But i think if you actually put a 5 amp fuse in place of main fuse and short the inside of traffo the 13 amp plug fuse will likely still go along with the now 5 amp (main) fuse. Thats the only reason i question if traffo was the short at all. As i said before, on more than one occasion i seen the copper links in a twin socket short when you plug in something. Or wiring inside metal socket box shorting of box where cable insulation is damaged, and the minute movement of pluging in something sets it off.

Anyway i think the traffo probably has nothing wrong with it. Any info OP?
Try plugging it in somewhere else is the best test.

Bruthal

2011 wrote: »

If you have reverse polarity the same current will flow through a fuse on the neutral as it would on the live, so it would make no difference.

In theory fuse discrimination works 100% of the time, in practice it is sometimes different.

Main fuses sometimes fail. That is life.

I will probably have a few questions of my own for yourself or mceebee soon as you are more up to date on the regs etc.