I had a severe short caused by a cable being dammaged on my laptop power supply (it was squashed by a filing cabinate drawer)..
Simple 2 core cable, and due to the type of flooring there was obviously no leakage to ground so the RCD wasn't activated. (It was squashed between a plastic foot and plastic flooring so was fully insulated and there was no ground cable to cause a ground fault)
Noticed a slight burning smell and my desktop computer, printer etc went off as there was no power at the socket the 20amp MCB on the panel tripped out.
Worryingly or interestingly, im not sure which but the 3amp fuse in the plug was still in perfect working order!!!
Dud fuse? or just slow blowing?
Seems very inadequate protection on a 35 amp ring!!!
djk, Does your laptop power supply have a box with a Transformer in it, to step down the voltage?, sometimes there is also a 3AG type fuse in this box, that protects the Primary side of the Transformer, but it sounds like if there was one, it never blew either. It sure sounds strange how that 3A fuse never blew, mind you, the MCB at the Panel may have had a better Time/Current characteristic than the fuse, which I assume was an HRC type?.
Let's face it, these days if you're not young, you're old - Red Green
#138105 - 08/17/0307:24 AMRe: So much for UK 3amp plug fuses!
If a 3A fuse stays in working order on a 20A MCB, what would happen to a 5A fuse on a 32A MCB? Or a 13A fuse?
The fuse installed in all British plugs conforms to BS 1362 ("General purpose fuse links for domestic and similar purposes…"). The size of this fuse is 6.3 x 25.4mm. It has a breaking capacity rating of 6000A and is constructed with a sand-filled ceramic tube. The time-current characteristic on this family of fuses is not necessarily consistent with any other international standard, but it appears to have most of the characteristics of a fast acting fuse.
Here is an experiment: Does a 13A fuse blow on a modern ring?
By the way, why are the fuses 3A? The smallest wire size is 0.5 mm² which is good for twice that.
[This message has been edited by C-H (edited 08-17-2003).]
#138109 - 08/17/0302:52 PMRe: So much for UK 3amp plug fuses!