sixwheeledbeast Posted January 26, 2011 Share Posted January 26, 2011 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? Link to comment https://www.thesecurityinstaller.co.uk/community/topic/30740-cat-5/page/2/#findComment-267948 Share on other sites More sharing options...
Cubit Posted January 26, 2011 Share Posted January 26, 2011 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?? Link to comment https://www.thesecurityinstaller.co.uk/community/topic/30740-cat-5/page/2/#findComment-267968 Share on other sites More sharing options...
PeterJames Posted January 26, 2011 Share Posted January 26, 2011 Why there and back?? Because the electrons run down the positive rail through the device and then back up the negative rail Link to comment https://www.thesecurityinstaller.co.uk/community/topic/30740-cat-5/page/2/#findComment-267969 Share on other sites More sharing options...
Cubit Posted January 26, 2011 Share Posted January 26, 2011 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. Link to comment https://www.thesecurityinstaller.co.uk/community/topic/30740-cat-5/page/2/#findComment-267970 Share on other sites More sharing options...
sjsturner Posted January 26, 2011 Share Posted January 26, 2011 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! Link to comment https://www.thesecurityinstaller.co.uk/community/topic/30740-cat-5/page/2/#findComment-267971 Share on other sites More sharing options...
Adi Posted January 26, 2011 Share Posted January 26, 2011 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 I really can't be ar**** with it anymore. Link to comment https://www.thesecurityinstaller.co.uk/community/topic/30740-cat-5/page/2/#findComment-267973 Share on other sites More sharing options...
arfur mo Posted January 27, 2011 Share Posted January 27, 2011 You fired lol! Arfur If you think education is difficult, try being stupid!!!! Link to comment https://www.thesecurityinstaller.co.uk/community/topic/30740-cat-5/page/2/#findComment-267987 Share on other sites More sharing options...
arfur mo Posted January 27, 2011 Share Posted January 27, 2011 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 If you think education is difficult, try being stupid!!!! Link to comment https://www.thesecurityinstaller.co.uk/community/topic/30740-cat-5/page/2/#findComment-267988 Share on other sites More sharing options...
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