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

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.

Yeah I dont know, its more the switching power and not the siren. I have the manual for it online. http://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.

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.

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.

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.