Just got curious about this last night when I was wiring a couple of LEDs on my brother's long board.
For a simple DC circuit (Battery, resistor, LED), how long can I stretch the wire until the power gets almost completely dissipated in the wire?
I know it depends on the battery and wire and everything so for like a 9V battery and 22awg solid wire...
I'm just looking for a way to come up with a rough estimate.
What about at a low AC frequency?

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up vote 4 down vote accepted

22 awg wire has a resistance of about 16.14 ohms per 1000 meters and has a max amperage of 0.92A according to this source.

Lets say you have a purely resistive load and maximize your current with 0 wire length, your load would be 9V/.92A=9.7826 Ohms. Using this as a voltage divider you would have:

250 ft - > 2.7 V drop
1000 ft -> 5.6 V drop
5000 ft -> 8.0 V drop

This are very rough numbers, but it is what I would use as an estimate.

Low AC frequency usually acts a lot like DC.

Please note though that you probably have a ground wire that has to go the same distance, so treat my lengths as "round trip".

I don't know if my method is 100% correct, but this is what I do.

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Interesting. My wires wont be more than 3 or 4 feet, so I don't have to worry. Thanks for the answer! – Shubham Jul 13 '11 at 2:13
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