That's assuming the system uses 2A at 12V.

And resistors in parallel exhibit an equivalent resistance of
Rt = 1 / ( 1/R1 + 1/R2 + 1/R3 + 1/R4)

So in theory, if you use all four in parallel, the equivalent resistance should be (at 100ft)

Rt = 1 / ( 1/3 + 1/3 + 1/3 + 1/3) = 1 / ( 4/3) = 3/4 = 0.75

Not bad
And assuming the same 2A @ 12V:

Vdrop = (2A)(0.75) = 1.5V

G.

Joel Jaeggli wrote:
On Wed, 12 Mar 2003, Gene wrote:


I guess it depends on the voltage too.


yeah at .0302 ohm per foot 24awg 3ohms per hundred feet... you're talking about a ~5volt drop so you put in 12 and get 7...


But if I remember my KCL/KVL and Ohm's Laws, what if you use the 4 unused lines in a standard PoE as the positive voltage rail and the shielding (assuming this is a shielded cat5) as the ground) to help reduce equivalent line resistance?
Aka "four heads...err...lines are better than one" idea.

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