ignition controlled circut

Hi,

I have always used an inline fuse off of my battery for any wiring jobs, but now I need to do one with more current and larger wire, and it must be ignition controlled. (Siren controller with switches for lights-fire department)

What I want to do is have it come on with the key in the run position, so I know I need a relay.  I think a relay is the way to go, but I need to run 10 guage wires from it to the battery with a 50 amp inline fuse also.  So one lead would go to the battery(10 guage 85?), another would be to the siren/controller(10 guage 86 mabye?), and an ignition controlled circut I belive(not sure what guage.)   I am having difficulties finding a relay that can switch 50 amps when the car is running, nor can I find an in line fuse that is 10 guage and 50 amps.  I have found a 60 amp inline maxi fuse holder with 8 guage wire, but that is alittle bigger than I want to use. I doubt the unit would ever draw 50 amps, but I want to wire it up like the manufacturer reccommends.  I am very confused with the numbers, as I see some diagrams with negitives in different places.  Basically this Is what I want to do:  Use the ignition circut as the switch to make the relay have power when the key is on.

Thanks!

Basically the relay will trigger when the coil is energized. This means that 85 and 86 needs BOTH a positive and negative to activate.
So if your "trigger" is a (+) then you would GND the other end so that when the relay gets that (+) from the trigger the relay engages.

The gauge if the wire depends on the LENGTH and CURRENT that is going to be used. So depending on the length of the wire that is going to carry the 50 amps the 10AWG may or may not be adequate.

As far as the relay type. I would suggest you drop by your local shop and ask for a high current relay. A 40amp relay should be fine your your use.

Hope this helps


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If you mount your relay close to the battery AND the siren (but make sure it's sealed and damp proofed (good insulating tape and water retarder, mounted with the terminals facing down). you shouldn't have that much grief. But what Siren draws 50amps? Even the older mechanical units only drew about 70-10 amps. That's nearly as much juice as a starter motor.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Yeah I dont know, its more the switching power and not the siren. I have the manual for it online. https://www.fedsig.com/products/docs/install/22-UM8000-00.pdf It says go straight to the battery with a breaker, so I think Im going to use 8 guage wire with a 50 amp inline fuse straight to the battery post. I dont see myself using that many amps to switch but I dont want to under power it...

I read that link, there's already ignition (or acc) switching.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Ahhh ok so it has one in it already. I wasnt sure what that meant. So if I hook that to an ignition controlled circut it should only be on when power is run on that wire. Does a certain ammount of current have to go through that wire? I dont want to overload that circut with that wire added onto it. I think I will throw on an inline fuse on that wire as well.
Thanks for the help!

Highly unlikely, probably about 100 milliamps.
Use a 1 amp fuse from ignition 1 wire.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Yeah I figured that. Ignition 1 wire, do you mean any ignition wire or a specific wire. Sorry for tge xonfusion, I never messed with any ignition wires.

The wire that goes hot (12v+) when the key is turned to ignition and stays hot when the key is turned to start (crank) position.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

I have no idea how much current your light bar will draw.  The difference between an ignition wire and an accessory wire is the ACC wire does not have power on it in the start position.  The power to most high current devices is removed while attempting to start.  I would think that an ACC wire would be a better option, or at least be thought about as an option.

Quite right Big Bird though I did mention ACC as an alternative before.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Yeah I would like to have it in the acc position. Where is the best place to get an acc wire? I would like to use my fuse pannel, so I believe a self tapper would be fine for it since it should only draw a few milli amps. The only thing is that my fuse pannel is relitively hard to access, and I like all my installations clean( split loom, zip ties, factory harnesses, etc.) I am not running a lightbar, just mirror, grille, haw, and dash lights, so the total draw is about 15-20 amps. But the possibility of using a lightbar eventually makes me want to run the larger wire. Thanks for the help guys.

Ignition switch, test, goes hot when ignition turned to 1st. position.

-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

I have no idea what kind of vehicle you have, it may or may not have a fuse labeled Radio.  If it does, check that fuse to see if will work for you.  Or tell us what kind of vehicle you have and we may be able to put you onto a suitable wire.

Ok here is my plan to do the circuit.  Open to changes because I do not want to overload anything or cause problems.  Also, I am not sure if that ignition wire turns off the whole unit, as it is listed as an on off for the backlights.  I cannot understand the technical diagram with all the wires broken down at the end of the manual, but mabye someone else can.  Also an update, there is an amplifier that goes with this aswell, so I need to provide power to that also, FedSig does not provide a reccommended fuse or wire size for it, so I will have to call them tomorow.

8 guage wire about three to four feet with an inline 60 amp blade fuse on it run through the firewall to under the drivers seat into an 8 guage in, 10 guage out splitter distribution box.  One 10 guage will go to the amplifier, the other will go to the controller.  It reccommends an 18 or 16 guage chassis ground for the controller, but a direct battery post gound for the amplifier.  An add a fuse 10 amp will go to the ignition wire, and will be added a spare ignition fuse on the fuse pannel.  The other positives will be run to the controller to power up the lights I will be using.  That should complete everything, and I should be set to go.  Currently, everything is inside loom, as it will be when I am done with this addition.

I think when I get this unit I am going to plug it into a multi meter and see how much it exactly draws, so I can cut down the wire size alittle bit.  As stated earlier, I currently have a 30 amp inline circuit with 12 guage wire powering a switch box.

Also, the vehicle is a 2005 Jeep Liberty sport.  I will also be installing 2 LED mirror lights when they come in with the siren unit.  That will give me a dual led dash light, two rear hide away leds in the taillight housing, a speaker, and two led grille lights. 

I am open to suggestions and corrections (the reason why I posted on the forum)  Thanks everyone, you are all very helpful.