Wire Help

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annie mouse
 
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Wire Help

Post by annie mouse »

I understand using 20 or 22AWG hookup wire for short runs but now I need to do a 4 wire run from my LED light strip to the Arduino about 6 feet away. Adafruit doesn't sell 4 wire cable and the outside sources re overwhelming in terms of unfamiliar specs (shielded? co-axial? Audio wire?) and seem overkill at 600V rating for my 5V project. Can I use Cat5 or Cat6 cable for this purpose?
Thanks

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adafruit_support_bill
 
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Re: Wire Help

Post by adafruit_support_bill »

For a 6' run, you shouldn't have to worry about shielding and such. Cat5/6 is probably OK, although 24Ga is a little on the lightweight side for power and ground. But with 8 conductors, you can use one pair for the signal wires and divide up the other 6 between power and ground.

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adafruit_support_mike
 
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Re: Wire Help

Post by adafruit_support_mike »

The amount of current you can run through a wire depends on the heat it will generate. Copper is an excellent conductor but it does have some resistance.. about 1/12th of an ohm per meter for the 24 gauge wire you'll find in a CAT5 cable.

Officially you calculate the resistance of the wire run, multiply that by the current squared to get the power dissipation, then apply the Stephan-Boltzmann equation to find the equilibrium between heat generation and heat dissipation.. which nobody actually does outside a physics class.

In practice you just look it up in a chart. Here's one that goes all the way down to 32 gauge: http://wiki.xtronics.com/index.php/Wire-Gauge_Ampacity

According to that, a 24 gauge conductor inside a cable can handle 2.1A, but that's an upper limit. I try to keep it below 1A per conductor myself.

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