On Friday, 18 November 2016 22:49:09 UTC, wrote:
On Wednesday, November 7, 2012 at 6:40:34 PM UTC, David Robinson wrote:
Not my question, or belief, but found here...

http://forums.digitalspy.co.uk/showthread.php?t=1755197


Is there a counter-argument?

Thanks,
David.

You're replying to a 4 year old discussion for some reason.

To "the fuse is there to protect the cable" ? Hmmm, that's rather to vague, and technically incorrect. I think you need to ask what are we protecting really, and I beg to differ that the fuse is there to protect the cable, here are some reasons why:

Really what we are protecting is ourselves and other property from electrocution and fire, The simple fact is that if the cable is overloaded then it will melt and cause a fire, it will then also short out the supply causing further risk.

That certainly isn't fact.

To illustrate lets consider the service fuse in your electricity supply, without it any short or overload would probably take out at least part of your street.
It's easy to forget that the fuse is there to protect against overload

maybe for strangely forgetful folk

because in most cases it's blown due to a direct short, but if you are running a 3KW heater on a 5A lighting circuit with a 13A fuse, that wire is going to melt sooner or later,

Rubbish. BTDT.

but even assuming it doesn't, over time the excess heat will make the plastic brittle and one day it will crack, perhaps when you pick up the cable! A 13A fuse will certainly protect a direct short an a 3A cable as it won't really have time to melt before the fuse blows, but if you want a demonstration of what can happen try dropping a some 13A stranded wire across a 12V car battery, make sure you aren't holding it and there is nothing combustable around though as the whole length will instantly burn all it's length before it vapourises- It's quite spectacular, yo might want to wear suitable eye protection as it could be quite bright.


It's all quite simple. 3A fuses aren't required for new goods that conform to the law, if extension leads aren't used. IOW in most cases 3A fuses are unnecessary. Now add the real life facts of old appliances, nonconforming goods, extension leads and daisy chained extension leads and it's easy to see why 3A fuses are still a smart idea.


NT