# Matching AWGs to Amperes

Hi guys!

i want to make a project in which i drive an IR led with 1A, i was wondering whether i need a specific wire for that, since 1A is not the common 200mA or less i work with. Is there a way to calculate the AWG (or standard diameter in mm) in relation to the current that will pass through it?

One other thing, is it safe to work with 1A (and 7.2V)? what happens if I ground a 1A wire (and 7.2V) through my body?

## Comment viewing options

Page 6 of this factsheet covers different types of wire and the section "copper cable characteristics" gives you information like amperage rating, resistance etc for stranded copper wire.

If you are using a limited dutycycle for example 50% then a smaller wire size can be used.

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

heres a good site that i found earlier. Scroll down for the table.

i had found the same site earlier but can't understand what "chassis wiring" means. could you help?
Chassis would be the normal wiring, between circuits, lamps, motors, whatever that is periodically switched on or off, given some time to rest. Especially if used in pulsing on and off in PWM. Power wiring is that which is expected to carry the current constantly, no rest, no off. Since they say the chassis wiring is a conservative estimate, you are probable fine with using the wire guage thye suggest there, about 29 guage.I'd probably use 28 or 26 guage since I probably have more of it.

rule is 10A for 1mm² ,  this is a ZERO risk value

regarding your own safety, you are always safe below 50V (dry) , below 25V (wet) , below 12V (in the water)

When you put a Voltage source across your body, say from finger to toe, your body will resist the current that wants to flow from one terminal to the other. You are now a Ohmic resistor.

The fact that your supply is capable of delivering (up to) 1 Ampere of current before the 7.2 V drops, makes no difference to your body's electrical properties.

So how high do you think that resistance is? Measured from finger to toe? A few Ohm? Maybe a few kilo Ohm? Apply Ohm's Law as usual and calculate the current through your body.

The electricity poses two different dangers to your health:
1) a power release (P=I*V where I=V/R so P=(V^2)/R) that will potentially burn your flesh
and
2) a neurological disturbance; your neurons work on the same electrical impulses, but are way more sensitive than your micro controller.

1)
Beware that the density of the discharge is highest near the terminals. I'm guessing you are just holding a piece of copper wire between your fingers/toes in this imaginary experiment. That is where the current flows through the smallest surface area (say 2 mm squared). A few mA through a surface area like that will not hurt you.

2) A few milli Ampere will however influence your heart rhythm. As in "KILL you". Butt hose mA must all go straight through the heart itself in order to stop it.

How much is "a few"? Ask this guy: he is tingling all over for science:

The only effect of that 12 V battery, that I can detect, is on his facial muscles, if you get what I mean { -). I am guessing his resistance is much higher than 12 V / 30 mA = 400 Ohm.

As always: check wikipedia for more serious sources.

8ik