wire thickness

[Thunderchild]

I bought a 2 KW fan heater and discovered that it only has a 0.75 mm2 wire. I took it to work as thats where i wanted to use it and well coincidently we had the guy in that checks our electrical gear for safety. I passed the heater ! I questioned him about it and he started to doubt his judgement so phoned his boss who waid that 0.75 mm2 was ok for the heater (with a 13 A fuse). I'm pretty sure that after 3 hours of use the wire was getting warm. Surely this wire is too small ?

 

[Nigel Goodwin]

If it's getting warm, that's only adding to the heat output

But it's just about OK for 2KW - personally I always like to consider the size of the cabe as the current rating - so 0.75mm would be 7.5A, and 1.25mm 12.5A etc. That's perhaps a little pessimistic though - have a look at Cable Conductor Size & Current Ratings

 

[Thunderchild]

oh nigel 10 A / mm2 ? thats not at all pessimistic, thats better than the chart you linked to, I've always worked by the rule of 5A/mm2 but then I like to make sure there will be no problems, considering its a heater and therefore the wire may find itself in an already "warm" working environment I think it should be thicker, I think 8.3 amps needs more than 0.75 mm2, the other issue being that the fuse is rated at 13 A so the cable should capable of 13 A no point in a 13A fuse if there cable is going to catch fire before it blows. of course it depends on the wires temperature rating, but then dare I assume that in china they used anything better than the worsed ? (in the case of your chat 60 deg which can carry 6A)

 

[mbarazeen]

10A/ mm2 is ok for ventilated areas. i have noticed most of the items use under rated wires and they always generate some heat. but no insidences i have heard so far, make sure you dont role the wire and use it, it may get fire easily.

 

[Thunderchild]

well my main concern is that having it under my bencch the wire trails up INFRONT of it so the hot air already warms a warm wire warn X warm = fire risk to me, I would have hoped any half decent manufacturer would derate the wire on a heating device by 50 %, why is does the 13 A socket bar on my bench have a wire that is twice the thickness yet my fan heater is half of that and is also rated at 13 A.

what I found more worrying was that the guy did not actually read the wire thickness on the cable but opened the plug and noted that there was not earth wire so assumed that it was ok..... cricky I suspected as much but now I'm sure that these safety checks are just another load of beurocratic rusbbish, in 30 seconds i had the guy in doubt of himself and this is the guy that will be telling me if a device is safe to use of not ?