Cat 5 relay triggers

c17loadsmasher · Post by **c17loadsmasher** » Fri Jun 18, 2004 11:58 am

Hello all.. I was pondering rewiring my truck to a more centrally located power supply center. My plan is to run B+ back to the board, and power the accessories via relays and bussbars. My swtichbox up front is one of those Galls' boxes made by Touchtronics...with the programmable buttons and pursuit switch. What I wanted to do was remove the bulk wiring up front, as currently there are about 2 dozen wires in wire loom coming up from underneath the console. I wanted to replace most of the power feeds with say, Cat 5 to trigger the relay, which would be back at the power center. This would give me 8 wires in one small package. The amperage would be just enough to trip the relay, and no more. The switchbox has 30A fuses for the output, I planned on dropping that down lower just to prevent cooking the Cat 5. Any thoughts on this? Also, any reccomendations on what size battery cable to run back to the power center? I'm running a Basic Vector lightbar, 60W strobe pack, Whelen Alpha Siren, two halogen flashers, wigwags, and a Kenwood TK-730G mobile with remote head. Any ideas would be most appreciated...I have a loose idea as to what I want to do, just want to know if it's feasible or not...

--Chris

SlimBob · Post by **SlimBob** » Fri Jun 18, 2004 1:28 pm

it would probably be best to use the CAT5 the way it was intended, that is... balanced... four circuits, equal current both ways.

Couldn't hurt, would cost a ton of relays, not to mention using non-SAE approved wire. Be sure to used stranded, solid won't take the motion.I'd run two or four of them, shielded of course, and do it that way... then you have spare pairs for failed circuits, etc.

firemedic2150 · Post by **firemedic2150** » Fri Jun 18, 2004 2:03 pm

I have four circuits done this way, I use small lighted rockers in the dash to switch the relays, they are connected to a run of cat-5 to the trunk. The lamps of the rockers have a small B+ feed up front to power the lamps, but the switched power for the rockers comes from the relay pack I built, to the front mounted switch panel on the cat-5. I used dual 8 guage runs directly from the battery to the trunk fuse panel /relay pack. I also have two remote mounted radio's on this same feed. This system has been it service for over a year with no problems at all. The current on the relay circuit through the cat-5 is very small.

Mark Mc.

c17loadsmasher · Post by **c17loadsmasher** » Fri Jun 18, 2004 4:01 pm

Yeah I figured that the load would be negligible...SAE approved or not. It's for my own vehicle, not for any sort of work that someone is paying me for, so if it goes down in a blaze of glory, then I have myself to blame...lol. In any event, didn't FedSig use Cat 5 for it's Smart Vector? (shrugs). I just wanted to make sure I wouldn't smoke the wiring the first time I activated the relay. In order to avoid having a whole ton of relays I was planning to have eah relay supply power to a terminal strip or bussbar, and then the accessories running from that. I dunno. It's all still in the works...

jim · Post by **jim** » Fri Jun 18, 2004 8:39 pm

Get a PDC10 board from TST. It has 10 relays and will take 160 amps load. You can install micro fuses on each relay for protection of the CAT5 cable. I always switch the ground side of the relay.

You can parallel 2 relays if necessary and it allows neg or pos switching. The board also has LED status indicators and fuse/breakers. Install a modular jack at the board and use the cat5 cable to switch the relays. A #6 cable should fulfill your needs.