Cat5e UTP Resistance is 0.938ohm per metre per core (depending on manufacturer).

Maximum cable voltage is 50Vdc/30Vac

0.938ohm * 50 metres * 2 (there and back)

93.8ohm

93.8ohm * 0.5A

46.9

46.9 / 12 Vdc

3.908

46.9/ 50 Vdc

0.938

3.9Vdc dropped @ 12 Vdc

0.9Vdc dropped @ 50 Vdc

I think I worked that out right!?

So James was right! 4-6volts

Maybe he could add it to the SIA Calculator?

Edited January 26, 201115 yr by sixwheeledbeast

Cat5e UTP Resistance is 0.938ohm per metre per core (depending on manufacturer).

Maximum cable voltage is 50Vdc/30Vac

0.938ohm * 50 metres * 2 (there and back)

93.8ohm

93.8ohm * 0.5A

46.9

46.9 / 12 Vdc

3.908

46.9/ 50 Vdc

0.938

3.9Vdc dropped @ 12 Vdc

0.9Vdc dropped @ 50 Vdc

I think I worked that out right!?

So James was right! 4-6volts

Maybe he could add it to the SIA Calculator?

Why there and back??

Why there and back??

Because the electrons run down the positive rail through the device and then back up the negative rail

Because the electrons run down the positive rail through the device and then back up the negative rail

That would be total cable volts drop. OP was concerned about V drop at load - 50metres. Also said using a pair each side.

Edited January 26, 201115 yr by Cubit

Because the electrons run down the positive rail through the device and then back up the negative rail

return current

have been advised before that its more benificial to double up the neg than the pos due to the return trip

odd because you would naturally assume to make the pos bigger!

colour cams with them little maplin's caravan solar panels work a treat, being colour cams there is no need to power them at night.

.........i'll get me coat

You fired lol!

Arfur

On the iP camera course, they mentioned cabling based on maximum legnth allowed (305 feet plug to plug).

the powered ports on the switches were 48 volts DC, I think @ 100 MA. for that distance. So could run a later low power ip camera (without extra power insertion).

If you can't get power at the camera end, say you took the pcb from a 1amp PSU to the camera end, by feeding it 30 bolts dc down the cat5e the psu board drops and stablises it to 13.6, would that be any better than doubling cores?

Arfur