how much current can AWG wire handle

Fusing current is pretty obvious isn't it ?

Also beware of operation at elevated temperatures and derate when bundled or run in trunking.

Graham

# 20 wire can carry any current you like, up to the fusing current. It is all a matter of how hot you are willing to let the wire get. The referenced table above will let you calculate the temperature rise of a wire over ambient for any arbitrary current and gauge.

The Current Carrying is how much current the wire can handle for a given rise in temperature over ambient. There should also be a note that the temperature rise will be more than calculated if the wires are in a bundle together. An unbundled #20 wire at 7.5 amps will rise about 30F (15C) over ambient, which is pretty warm. Your call.

Fusing current is the current at which the wire will melt.

Jim

The current carrying capacity in the listed table is based on 700 circular mills per amp, a very conservative number for wire wound inside a transformer where heating is an issue.

The National electric code specifies current carrying capacity for open wires or house wiring for example about twice that or 300 to 350 circular mills per amp. This gives 20 AWG wire about a 3 Amp rating.

What is your application? What is the duty cycle? What is the thermal environment, how hot can it get? Is it in a transformer or in open air and how insulated? How much voltage drop can you tolerate?

Back in the day, the usual rule of thumb for low-frequency power transformers in continuous use was 1000 circular mils per amp, where a 'circular mil' is the square of the diameter in mils (thousandths of an inch), i.e. 1 circular mil = (pi/4) square mil. The 1000 circular mils per amp rule comes out to 5.07e-6 square metres per amp.

Cheers,

Phil Hobbs

But before the wire gets too hot, there will probably be so much voltage drop that the voltage at the load is too low, so that might be the more important criterion.

A rather consrvative rule of thumb is as follows: find out the area in circular mils, and use that number as the maximum number of milliamperes to flow in that wire.

Mil is confusing. A lot of folk in metric countries say "mil" short for millimetre. A metre is considerably different to an inch.

P.S., what's a click?

? "Peter Hucker" ?????? ??? ?????? news: snipped-for-privacy@fx62.mshome.net...

No, we don't. We usually say mm. Rough comparison: #10->10 mm^2 , 35 A fuse for main residence #12->6 mm^2, 25 A for stove #14->4 mm^2, 20 A water heater #16->2.5 mm^2, 16 Awashing machine, dishwasher #18->1.5 mm^2, 10 A lighting These figures are for one live conductor in a conduit inside the wall.

When I was in Rhodes (east Greece), we were camping with my 542nd mechanized infantry battalion, and there were lots of scorpions. We had brought a wooden bank with us, and at bed time I saw a sergeant laying to sleep on the bench. I asked, 'Is sir something wrong, I could help' he said just leave me alone. I learnt from his colleagues that he found a scorpion under his pillow (in his tent) and the "brave" sergeant decided to sleep on the bench. Soldiers wished to be bitten, so that they could get sick leave.

Designers in the UK doing technical drawing often say "400 mils" to mean 400mm. Just in speach though, it is written as mm.

Common speak in the workshop too.

Yes they do, almost universally in the British speaking ones.

No, that's a THOU, for a thousandth of an inch.

Graham

Come to think of it, the prefix milli is just plain wrong. Either that or the word million in wrong.