Fake Fuses.

Yes I believe that it could under adverse conditions of very high PSCC

Not a moulded one, but the plug could be ejected from a socket if the fuse carrier were expelled.

Why did intersafe not use an image of fake BS1362 fuses? None of the fuses shown would appear to fit in a BS1362A plug.

I am not against Intersafe highlighting the issue, but an image of fake BS1362 fuses would at least help identify them.

Their first bullet point 

• The most important thing to notice is the diameter of the fuse wire in the unknown brand, it is significantly wider than the genuine 5 amp and of an unknown rating

I have never seen a glass bodied B£1362 fuse, so how do you check the fuse wire diameter?

Clive

Could a fake 13 Amp. plug fuse really blow off the top of


Well in the best 'blow the bloody doors off' tradition, lets do some thinking.



1) gut feel not likely if the circuit feeding it is a modern MCB, either C type 16A or B type 32A.


However, if it was plugged into a circuit protected by a BS3036 hot wire fuse, especially one with a bit of metal coat hanger instead of the original fuse wire, then the let -through energy would be that of the company fuse.

Let's see...


If we assume the fake fuse has a similar resistance to a real one and dissipates 1 watt at 13A, then its resistance is 1/13^2 ohms or about 6 milliohms.



So what is the energy that it will dissipate in joules, well that resistance times the I2t value for the upstream fuse/ADS.


I2t for 30A BS3036 perhaps 160 kilojoules per ohm (say 400A for 0,1 seconds), or about 90 joules in our fake fuse.


if the hot wire fuse has been by-passed for show, then we are looking at maybe a 60A BS1361 perhaps

I2t  is then more like 800kjoules per ohm , so more like 500 joules in the fake fuse (and enough to overheat the plastic,  but not fuse the metal on any 2.5mm2 cable supplying it as well)


To  put that into perspective the energy of a bullet leaving the strongest  air rifle that does not need a licence in the UK is a  little under 5 joules. At point blank range you may get that to crack a plug, but more likely take a chip out of it.

A gram of TNT releases about 4000 joules,  400J or 0.1grams of TNT equivalent would destroy a UK plug, I'm less sure about the total destruction of the plug with 90 joules. It may well blow the back off though.

Mike.

There is a video of a fake fuse exploding at https://www.youtube.com/watch?v=KVJVswLbqaA

(This is just the first one I looked at as I have seen multiple examples in the past - at least with this one it automatically unplugged the faulty device ?)


I agree with Clive about the problems of checking the wire diameter but I think that this is not likely to be needed as most fake fuse will have failed on the other bullet points. Perhaps if the other bullet points are deemed to be uncertain one fuse of a batch should be broken open as a check.


Alasdair