I need to make some alterations to the wiring of my HID kit. It is wired with 18 AWG cable. No-one over here really seems able to make any sense of that scale, so whats that in AMPS?

I had thought 17 AMP cable would be sufficient, but it is fitted with 25 AMP fuses. However the 25 AMP cable is alot thicker looking than the 18 AWG stuff.

Help!!

 

http://www.powerstream.com/Wire_Size.htm

 

AWG is american wire gauge, 18 awg is near as damn it 1mm

 

OK, looking at that, 17 AMP cable would do it. So, if thats the case, how can what its supplying have 25 AMP fuses in? Surely the wire would melt before the fuse blew??

 

Fuse is just there to protect from a dangerous overload, because you have a 25amp fuse, it doesn't mean the HID kit draws 25 amps. That just the safety cutoff the manufacturer had deemed necessary.

 

The reason is some fuses are rated continuous, like older glass fuses, some like Blade fuses are rated as blow ratings.
The rating of wire is always continuous, a 17 amp cable wille asily supply temporarily 25 amps top blow fuse.
Best way of working out amperage cable need is V/I X R, or watts /volts = amps.
18 AWG is 0.823 mm/2, 1.624 circular mm.
Additionaly thinwal cable carries around 35% more current than std insulation at the same thickness.
tabetha

 

Size of wire inside a 25amp fuse is approx 0.75 mm

Size of 18awg is approx 1.00mm

A 25amp fuse is going to melt first.

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18 AWG is 1.0236mm

 

Most places seem to sell the cables in AMP rating, either 17 or 25 AMP. So, would 17 AMP be sufficient, based on the fact that its 18 AWG at moment?

 

I'd go for 25amp thin wall.
As you will only need a few metres there's not much in the cost difference.


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Think you're getting mixed up with circular mm, as 20 gauge is 1.022
Taken straight out of NEC(brown and sharp).
tabetha

 

what is circular mm then?