Not sure if this will work

[Rob95655]

I'll try to keep this short as I am a newbie to the board. If I have left out some vital information please ask.

I have a light bar I am trying to mount to my vehicle as a "quick disconnect" to be able to install it quickly when needed and remove just as easy. The current setup requires 7 wires to run the bar with another 9 to run a traffic director mounted inside.

The bar itself (strobes, alley lights and takedown lights) is a positive switched system...the traffic director is a negative switched system.

Running 16 wires to the light bar makes for a huge harness. I don't mind the size so much but to make it quick disconnect would require the use of the "mil-spec" multi-pin connectors for the electrics. I love those, but the crimp tool costs in the ballpark of $400, so I am trying to work around that.

My idea to make a thinner cable harness was to mount relays inside the light bar, run a main hot lead and ground lead, then use something like CAT5 or CAT6 outdoor (uv) rated cables as "triggers" for the relays.

A few questions:
1) Can CAT5/6 wire handle 12v? My Carling switch panel would provide 12v (unknown amps but probably not much) to trigger the relay to switch on, using power from the main power buss I would mount inside.

2) I read that relays could be used to "reverse polarity" but not how to wire them. The traffic director control box uses one lead as hot that goes to the lights, the has 8 negative wires coming back, switching the circuits on inside the controller. The controller is "intelligent" (per the manufacturer), so I am guessing the hot out must need to ground somewhere then another 12v must be returned for the unit to turn on and off the particular light).

3) If this is possible (use CAT5/6 as control wires), does anyone know of a way I can mount a receptacle to the roof of my truck and make it weatherproof? Preferably something panel mount to keep the profile low for when the light bar is not in use. Picture a wall mount Ethernet jack but maybe 1" round with a jam nut type of setup. I am sure I could break out a dremel and make one, but the prospect of not finding out I messed it up until AFTER I have a ruined headliner doesn't appeal to me, so I am willing to buy a proven jack.

If I am completely off the mark and sound crazy, please be gentle.

Thanks!

 

[KJ6EAD]

The easiest solution would be to choose another connector that you can use a $30 hand crimper or solder to. What size are the wires?

 

[Rob95655]

The current wires are 12/14/18 gauge depending on the wattage of the bulb(s) it is powering. My problem is I am running the wires on a much longer run than the manufacturer suggests since I am making it "quick-disconnect". Usually they permanent mount through the roof so you only run 8 feet or so. I am running from the middle of the passenger door all the way to the back hatch of a Ford Excursion, then all the way down to the bumper, inside and all the way back to the A pillar and to the center of the dash. That small of a wire gauge will end up getting too hot and losing too much.

I was thinking of the CAT5/6 solution with relays so I would only need to run 1 hot wire (say 8 gauge or bigger), one ground to the roof rack mount bolt (again, maybe 8 gauge), then the smaller CAT5/6 as trigger wires.

 

[Rob95655]

What size are the wires?

If I can find a connector with enough pins I suppose I could run multiple pins as power to make up for the small gauge...

 

[SABorn]

Why not look at running 2 cable looms together to get the required number of wires, the thought that comes to mind here is the mulit wire loom cable used to wire a trailer lights with, not sure on what is used in your part of the world, but most times you can get different number of wires in the looms.

As for plugs then use a couple of trailer plugs as well, they are robust easy to connect to, and cheap, also will handle the amps you need, if you get 2 different types then there is no risk of getting the plugs mixed up.

 

[KJ6EAD]

You really need to map out exactly how much current capability is needed for each line before you design the cabling and connectors.

If you do decide to use remote relays, don't use category cable. It's a very poor choice since it's solid wire not designed for flexure in service. You would want to use stranded multiconductor control cable designed for automotive, industrial and robotics applications. Something like this or a similar offering would work:
**broken link removed**
If you could find something in 22 or 24 gauge, the control cable would be smaller that 0.5"

 

[KeepItSimpleStupid]

Here is a 7 pin IP67 rated connector: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=APSDSF2-ND It aparently comes in 12 pos, but DG doesn't have both parts.

The IP67 rated stuff will probably be solder and not crimp.

We don't know what the control signals do, so not sure if you might be able to use RF, a serial link or even tones (Think DTMF of Touch-tone phones).