# When routing power how is a safe current-carrying wire configuration determined with multiple wires?

I've been looking at a device/power-supply pair I was sent recently for a project.

The device specs say it needs 24V and will draw 10A max.

The power supply provides 24V @ 9A (14A peak).

The power supply has 3 posts for V+ and 3 posts for GND (call them V0, V1, V2, G0, G1, and G2 respectively).

The cable that was supplied bundles 14 24 AWG wires, connected into a molex receptacle such that 2 wires go to V0, 2 to V1, 3 to V2, 2 to G0, 2 to G1, and 3 to G2.

I looked at a load-limit table for 24 AWG wire and it says that for chassis wiring, the wire is rated for 3.5A max and for power transmission 0.577A max.

Since the device can draw up to 10A, clearly a single piece of 24 AWG would be too small to be safe in this configuration.

The only conclusion I can draw from this is that using 7 wires across 3 terminals spreads the current load out such that 24 AWG is safe.

My questions, if you've managed to get this far are:

1) What is the calculation to determine the correct minimum number of smaller gauge wires to use in such a setup (i.e. where you're replacing a single larger wire)? Is it simply max current draw / number of wires?

2) How is the voltage drop due to the wire length calculated when using multiple wires (I know how to do it with one wire)?

Thank you!

• I might be wrong but your supply seems less than adequate. If your load can pull 10A continuosly you might have problems, moreover using a piece of equipment on the edge of its maximum ratings isn't generally a good idea. Commented Aug 3, 2014 at 8:26
• The device draws 4A average 10A peak and the PS supplies 9A with 14A peak. They're sold together from the manufacturer.
– par
Commented Aug 3, 2014 at 17:01
• Well that's fair enough then. Commented Aug 3, 2014 at 17:35