Best way to use Cat5 for LV power

[George M]

I have numerous Cat 5 runs to motion sensors and soon to cameras. I am always wondering what is the best way to use the pairs to run power for these items (5V or 12V)

Let’s say I use the Brown and Green.

1. Brown for + and Brown / White for -?
2. Brown pair (solid and solid / white) for + and Green pair for -?
3. Brown and Green for + and Brown / White and Green / White for - ?

Is there a better way?

Thanks
George M

 

[pipeman]

I'll take door #3 Monty :huh:
Not that I know why, but that is what I use.
Less likely voltage drop by using two pairs, a little noise cancellation by using each twisted pair for the outs and backs.
If it were AC power, it would make even more sense.

 

[AceCannon]

I have 8 locations each with a motion along with a 32ohm Elk 1-gang speaker. A single run of cat5e includes:

1 pair for 12v DC to the motion
1 pair for the NC terminals of the motion
2 pair for the speaker (doubling up on conductors)

This setup has been working fine for me for 3 months or so.

 

[signal15]

I have 8 locations each with a motion along with a 32ohm Elk 1-gang speaker. A single run of cat5e includes:

1 pair for 12v DC to the motion
1 pair for the NC terminals of the motion
2 pair for the speaker (doubling up on conductors)

This setup has been working fine for me for 3 months or so.

Did you notice a difference in sound quality when you doubled up the conductors on those small speakers? I have only one pair of a 23awg cat-6 running to the speakers, and I'm not overwhelmed by awesome sound quality. Did you compare it to using one pair, or did you just use two right off the bat?

 

[AceCannon]

Did you notice a difference in sound quality when you doubled up the conductors on those small speakers? I have only one pair of a 23awg cat-6 running to the speakers, and I'm not overwhelmed by awesome sound quality. Did you compare it to using one pair, or did you just use two right off the bat?

Used two pair right off the bat. Sorry I can't provide more data.

But, of course you realize my cat5e is only 24ga per conductor.

 

[PaulD]

If you are using RJ45 type connectory, you may want to use a convention that reduces the chance of doing damage to equipment that is inadvertenly plugged in to a connector. One way to help in that reguard it to follow one of the PoE appraoches such as described on this page http://www.altair.org/labnotes_POE.html

 

[George M]

So from that document it looks like #2 is preferable.

George M