Phone line (modular wire) wattage capacity

[vassock]

What is the power capacity of a 28 AWG phone line-type modular wire? Can it handle 200 milliamps at 12 volts, like the power requirement of a simple car backup camera?

 

[AnalogKid]

Yes. 28 ga. wire has about 66 ohms of resistance per thousand feet, so a 10 foot long wire pair would have a total resistance of approx. 1.3 ohms. At 200 mA that's a voltage drop of about 1/4 volt. Not great, but the camera should be able to run on that. If you have an extra pair and can run two in parallel, that would be better.

ak

 

[Minder]

The NEC ampacity rating for 28 AWG is 800ma.
M.

 

[vassock]

Do these wires cause electrical fires if the limits are exceeded or if there is a short circuit or do they just melt inside the insulation without any risk of fire?

 

[CDRIVE]

Without a fuse all wire can burn if the source can supply enough current to do so. If it's being powered from an automobile battery I would definitely fuse it.
Edit: A 1A fuse should work fine. You can buy In-Line fuse holders at your auto supply, Radio Shack ebay, etc.

Chris

 

[GPG]

power requirement of a simple car backup camera?

If you have reversing lights the run could be even shorter assuming an RF linked system