Current rating of phone jacks

[Oznog]

I am considering if the typical phone or network jacks might be good for interconnecting my projects' data bus.

One thought is I'd like to carry 12V power through the same jack. Now this brings up a question- how much current is that kind of thin wire and jack pins rated for? I don't know the exact current the project will draw yet. Total's gotta be under an amp I'm sure.

 

[mneary]

Typical "phone" (1/4" diameter) jacks short the male side while being mated. (I do have some with a plastic body that don't...)

[edit] Or, I guess you mean RJ11 and RJ45.[/edit]

 

[mneary]

So, typical (at least in my lab) 4-pair network wire is 24AWG. If it's plenum rated, it should carry up to 3A without overheating. (ref) But at 0.03 ohms per foot the voltage loss adds up quickly. Don't forget to consider the path in both directions for voltage loss.

At 1A, you lose a volt (round-trip) every 16 feet.

 

[TheVictim]

Hmmm. Where did I put that old blotto box...

 

[Nigel Goodwin]

Typical "phone" (1/4" diameter) jacks short the male side while being mated. (I do have some with a plastic body that don't...)

Normal 1/4 inch audio type jack plugs do, but the old BT jack plugs don't, they are specifically designed not to.

 

[CheapSlider]

Have looked at **broken link removed** (Power over Ethernet) ?
This suggests up to 400mA which would give about 3 Watts at 12V.

Normal phone uses around 50V at 50mA DC and/or 80V AC at 75mA

 

[Oznog]

Yeah I mean phone jack- RJ11/RJ45. Not a phono jack like a walkman.

 

[kchriste]

The wire typically used with RJ11 telephone plugs is 28 AWG which won't carry much current. RJ45 network cables use heavier gauge wire and there are more conductors so you can easily parallel them.
http://www.interfacebus.com/Copper_Wire_AWG_SIze.html