# Drop voltage in wire [closed]

Hi I have hup swich that have converter 5 v 600 mamp in length wire 30 meter it work and shut off but I bring converter 1000 mamp and it work good ,what the drop or lost power ? By the way in utp cat 5 pumped power in

## closed as unclear what you're asking by uint128_t, Asmyldof, PeterJ, Rev1.0, JREApr 5 '16 at 7:38

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• Welcome to EE.SE, Omar. It appears that English is not your first language. Can you get someone to help you with writing the question? (We can't understand what you are asking.) Use "mA", not "mamp". What is a "hup swich"? – Transistor Apr 4 '16 at 13:30

(I am really juts guessing what you tried to ask there)

Lets assume 0.1 Ohm/m for a good CAT5 cable.

30m x 0.1 Ohm/m = 3 Ohm

Voltage drops:

V = 600mA * 3 Ohm = 1.8V

V = 1000mA * 3 Ohm = 3V

The voltage drop gets just too high for your 5V device to work.

Correct me if I understood your question wrong: You're powering a network hub with two different 5 V AC/DC converters through 30 meters of wire, one rated at 1000 mA that works fine and a 500 mA one that makes the hub turn off.

Have you considered that the hub simply draws so much current that the DC voltage at the jack drops below the minimum with the weaker adapter? It's not hard to test that with a multimeter.