I want to make a switched distribution block

[mob]

Hey guys, I want to make some kind of fused distribution block for all my accessories that is switched. I really dont want to tap into another wire to run all these accessories. What would be needed to just run a 8-10 gauge wire from the battery to a distribution block with a switch in the middle of it, that I could flip before starting the car. What I need to use a high amp relay? Or a high amp switch? Can anyone inform me on how to do this right? Thanks.

Accessories I plan on running include, electric fan controller, MSD ignition box, nitrous kit, thats all I can think of now, maybe will ad some other things later.

 

[93project]

I have an audio style distribution block up in the engine bay, while my battery is in the trunk. I have it powering my msd box, fan(s). It has a haeavy 4 gauge wire running to the power side of the starter solenoid. Each accessory has a smaller 8 gauge wire going from it to the block. The block has four slots for power and each can take those large glass fuses, which are too old school, or what I use, the large MAX 30 or 40 fuses. I just carry a few spares with me. The MSD is always hot, as it would be normally when hooked to the battery and I have the fan powered there, but swithced through relays and switches mounted inside. I can get pics for you if you'd like.

 

[mob]

Yea if you could get some pics for me that would be cool. I dont really want to have switches for each accessory, ideally I would like to tap into the ignition switch but I want to put a big gauge wire for all these things, so I am thinking if I could have one switch to power the added fuse box that would work just fine. I just dont know what type of switch I should use, or if there needs to be a relay built into this.

 

[93project]

If you have a fan controller, you don't need a switch. I have one for my fans because I don't like relying on an automatic switch controlling my cooling. One more thing that can go bad at the wrong time...... I prefer controlling fans as as I see fit. I don't have a switch for anything else.

 

[93project]

Here's a pic of the block itself. Those two smaller wires feed the MSD and the fan (#1). #2 fan isn't wired up yet. that fat 0 gauge cable is my battery cable that runs from the battery to the solenoid. I'm gonna run the two small wires through a black wire loom once I get the car done

 

[HISSIN50]

You can use just the switch for low current items (triggering a relay in a fan controller, etc). For heavier items, add a relay to the circuit. Do you know what kind of draw the box and nitrous create?

 

[mob]

No I have no idea what kind of current they draw, how could I find out?

I am going to be using a relay anyways on the accessories, like the nitrous, and purge kit, and bottle heater are all going to have their own relay, but the relays still need a switched 12v source. The only thing that wont have a relay is the ignition box because the instructions never said to install one.

Maybe a diagram of what I want to do will help. Let me see what I can do.

 

[mob]

Here basically I just want to flip this switch to power the distribution block so it would be like a "switched" 12v source for all the relays and accessories that dont use relays. Is this ok or would it be ok to just run a small wire from the ignition switch to do the same thing and power the distribution block?

(Obviously the relays have other wires but I am looking at just the switched wire.)

 

[HISSIN50]

That should be ok. I just worry about switch failure (it failing would shut off power to your igntion box and cause the car to stall).

I would almost rather run the box separately (most draw under 10 amps but you need to check and choose a donor circuit accordingly).

 

[93project]

why do you want a switch between power and distribution block?

 

[mob]

HISSIN should I use some kind of high amp switch? I wouldnt mind running the box seperatley from the block, that would make sense.

93project, most of my accessories have 2 power wires, a constant 12v source, and a 12v source when you turn the key or switched source. I have the constant source I am using the starter solenoid, i need a source for the switched 12v.

 

[HISSIN50]

Yeah, you'll want to use a high quality, high current switch no matter what.

Your distribution block right now will only supply a couple of amps or less (assuming the box is not run through it). Instead of the switch, you could just use a SPST relay, tapped into accessory power to turn it on (86 would go to accessory power to trigger the relay. 30: fused battery power).

 

[mob]

You mean use the relay to turn on the distribution block right? That sounds like it would be better then the switch, would that allow me to run more amps through the block? A SPST relay is just a standard 4 pin relay correct? Should I use a high amp relay, I have a couple 80amp relays, or will a standard 40 amp do? Would it matter what wire I use for the accessory wire?

 

[HISSIN50]

You can use the relay as the distribution block. You only have a few items on the circuit and a relay-coil only draws about 250 mA (0.25 Amps). So if you're triggering a fan relay and a couple of nitrous relays, the total draw would be 1-2 amps.

You're right about the relay. You can use either a SPST and SPDT.

A 30 or 40 amp relay would be more than ample. Just use a quality brand so it's as reliable as possible.

 

[mob]

Ok, I got you, so just connect all the accessory power wires to the same terminal on the relay? Sorry if these questions sound stupid, I am still trying to get the concept of relays down, I have wired a couple up but only by following strict instructions, I wouldnt be able to do it just by looking at it.

In this case I would grounf 85, connect all the accessories to 87, 86 is the switched source, and 30 is constant 12v correct? I have a Bosch 40A lying around so I'll use that.

 

[jrichker]

I see a trip to Skycraft in your future...

 

[mob]

hahaha you're right Joe, I cant wait to go and get me all kinds of goodies.

 

[HISSIN50]

Ok, I got you, so just connect all the accessory power wires to the same terminal on the relay? Sorry if these questions sound stupid, I am still trying to get the concept of relays down, I have wired a couple up but only by following strict instructions, I wouldnt be able to do it just by looking at it.

In this case I would grounf 85, connect all the accessories to 87, 86 is the switched source, and 30 is constant 12v correct? I have a Bosch 40A lying around so I'll use that.

That would do it. Your distribution relay would have several wires attached to 87 (a leg going to 86 on the fan relay and a leg to each of the two nitrous relays).

Or to eliminate the distribution relay, just run accessory power to each of your 3 relays (the fan relay and two nitrous relays). This will only burden your donor circuit with an extra amp or so of current draw (the power to energize the 3 relay coils). Most decent sized accessory circuits can handle this.

 

[mob]

hmmm that makes sense, I guess thats what all those relays are there for anyways. I guess this whole idea was pointless haha.

 

[HISSIN50]

Nick, the idea of a power-point is always nice. With a different array of components (items without relays already, or items that are not hindered by a relay), it's a great way to go. And it would do fine here too - it's just more complicated than it needs to be.

If one is able, it can be nice to install a small fusebox, where all of your relay outputs are fused, along with the battery feed to the relays, and even the trigger wires (1-3 amp fuses do well). The relays can be contained here in an orderly fashion as well. Remotely related, I had once thought of getting a SN95 underhood-fusebox and installing it in the fox. I just never got around to it.