wiring switches from a console

Joined: 30 Jun 2004 Location: Brisbane sometimes

Hi all.

i have a couple of wiring questions for you all. I am setting up the switches on my roof console, and am running the cables to trigger the solenoids in the rear of the cab. The cable run is about 4m long via the roof channel, down the b pillar then down to the rear of the cab under the bench seat. the cables will be used to activate air locker air solenoids, a 12v 30 amp solenoid for my rooftop spotties, and a 30amp solenoid to activate my air compressors. will light guage speaker wire be heavy enough to activate the solenoids? they won't be running the items, just the solenoids.

Also to minimze the number of cables, i am running a 5mm permanent hot, 5mm Earth and 5mm ignition hot to the console for the stereo, UHF, and cig lighter power source. My plan is to run a single wire from the hot to the switch in the console, then a single wire down to the solenoids at the back, then a single wire out of the solenoid to a ground. Does this make sense? That way only one cable has to travel the length of the car.

Joined: 30 Jun 2004 Location: Brisbane sometimes

actually thinking about it i would only earths from the switches, via the solenoid, then to a hot cable that is powering the compressor. That way i don't have hot cables running the length of the cab.

Joined: 11 Jan 2004 Location: Adelaide

The basic concept sounds good, but it's not clear (to me) how much load you have there, and precisely how big the "5mm" cable is. Is that 5mmsq, 5mm core diameter or 5mm insulation diameter?

You mention "air compressors" (plural.) Is that a typo, or do you have two? I wouldn't like to rely on one 30A solenoid to run two air compressors - unless they're tiny?

Roof spotties + air compressor(s) sounds like a significant load - I'm not sure about the 5mm cable, but drivesafe should be able to advise on that. Smile

Also, 5mm cable for the ignition hot is possibly overkill. I'd be more inclined to run a signal wire and use a relay to split the permanent feed into an "ignition on" supply.

Where is your battery? Under the bonnet, or in the back? If it's under the bonnet I'm not sure why you want a roof spotlight relay under the seat.

Posted: Fri Apr 04, 2008 7:32 pm

most solenoids will trip at about 100mA or 150, therefore speaker wire should work fine, as all your doing is adding voltage to a field in the solenoid so it knows when to switch your theoretically not actually powering anything, so light guage crappy wire will do Very Happy

Joined: 11 Dec 2004 Location: Gold Coast

Hi rockcrawler31, you state “switches”, how many are you talking about because you may find it easier and cheaper to get yourself some 4 core or 6 core security cable from Dick Smiths of Jaycar and use the one cable run to control all your solenoids.

This cable is pretty small but automotive solenoids or relays only need about 9 volts to operate them so any voltage drop that occurs will have no effect on the operation of the relays.

I use to operate all my driving and fog lights using one length of 6 core security cable so you will have no problems.

Just a suggestion, cheers. Idea

Joined: 07 Aug 2003 Location: Townsville

I would also go with earth switching rather than "hot" switching to the relays/solenoids. Far easier to deal with if something goes ZAP through vibration in the channels. Worst that will happen with earth switching is the relay would remain on.

Posted: Sun Apr 06, 2008 11:16 am

damika makes a great point, use all negative trigger relays, then use your switches to switch the relay pin to ground, its a much safer way of doing it!

Joined: 30 Jun 2004 Location: Brisbane sometimes

Hi all

sorry for taking a while to get back.

firstly i am currently running only one compressor with plans for a second one on the way. when that occurs i will have a dedicated relay for each one.

The reason i have decided to go with a dedicated 5mm (mm/2 core size 72 fine strand) ignition and permanent cable is because the constant hot is for a power outlet for fridges or inverters, and the ignition will have to run a hi power UHF/VHF (50w). So i don't want a single cable having to supply current to both at once.

It looks like in the end i will have to have "hot" trigger cables as i would have to run a hot ignition cable to the back to have an earth trigger anyways so i can't see how it would matter either way.

the 5mm cable is only going up to the roof console (see build up thread), the light cable is going from roof console to rear as trigger wires, which will trip relays. there is a cable coming from the front cranking batteries to the rear of the car that will power the items themselves as well as supplying the deep cycle batteries via an isolator. this cable is battery cable sized.