You still need relays with this though right? Why not make a box like I posted that has all the relays and fuses in one little box?

Quoting myself haha.

Anyway, I made that small one for like $20. The ISO relays are free from any JY, fuses/wire/connectors I had already (you prob do too, but even if not they're cheap), box is a small Project Box from RadioShack, and the fuse panel can be had at any Advance auto for $6.

This is what I have for the small stuff inside the car paired with 2000 Chero's PDC. The leds are awesome for easily telling which fuses are blown and doesn't need to be grounded

Not everything needs a relay, but you can wire some in to use with higher amp draw items. I'm not using a relay for my led rock lights.

While I agree that everything doesn't need a relay, and almost went that route myself, it requires the "hot" wires for the accessory to be run in your cab.

Also if you have more than one accessory, like I do with the over head switch panel (or any panel), that means at least 2 wires for each accessory from the engine to in cab. Where as with relays you just have the relay control wire, which can be as small as CAT5 cable. The looms size for my overhead to have all my accessories not run off relays would have been huge haha. Instead of the one CAT5 cable I have now.

I technically don't (according to math and charts) need relays for any of my lights, bumper/a-pillar/reverse, but I feel safer knowing all the "hot" wires are in the engine bay and not running into my cab.

Can I ask why you wouldn't just run the hot wire to the accessories from either the constant hot or switched hot and then fire the ground to the device from the switch inside the cab? Just curious, thanks.

In a word, ignorance. I should have consulted the almighty forum beforehand.

I wasn't expecting that reply, I was just curious. It is such an odd thing that in your house you break the hot wire with the switch but that application isn't always applied elsewhere. Most of the things that I work on in my job day to day are typically always hot and the I/O, button or switch fires a ground to complete the circuits. It seems like autos should be the same but for some reason the diagrams always show the hot wire being on the switches. Just firing a ground through a switch or relay would be less stress on the contacts if you ask me.

You have it right, completing ground is how the e-fan is turned on. Not sure about long runs of ground wire however. Seems grounds are always short in 12 volt DC.

Yeah but that is easily explained, chassis ground. It took me a bit to figure out how the ground system worked on an auto and I still have questions but I intend to do some lighting stuff at some point and was just going to run the ground through the switches inside of the car I guess I am more looking for a blatant pitfall that I am not seeing.

The resistance of the wire, I was seeing some dips in my volt gauge when my defrost was on high/heat. The ground on the outside of the condenser was not a dead short to ground on the battery or chassis, I cleaned it up and no more voltage drops. Shorter runs to ground, less resistance.

I ended up getting this setup.


As well as this for in the cab. between my gps, sattelite radio and cell phone charger, i use allot of 12v plugs

I feel like for the money you just spent on all that, without relays, you could have just bought or made one with relays for a lot less, and not have to worry about mounting them separate. Just my opinion though.

everything that will be plugged in to this already has its own relay or doesn't need one. This is simply an extension of my positive battery post to reduce the number of wires hanging off the terminal.

Nope. There is nothing wrong at all with your approach. It makes for a clean installation with few wires. Kudos on using CAT5 to switch relays - that's creative, and reduces the volume of wire you are running.



There's nothing odd about it. It's done for safety. If you break the neutral, your appliances are always hot. That's a great way to have more people electrocuted.

With low voltage stuff the electrocution risk isn't there, plus the actual ground (the stuff we walk on) is not part of the power circuit as it is with house wiring.



Now that is what's odd. What kind of things do you work on?

No, it's exactly the same. The exact same current flows through the ground circuit as flows through the hot side. Mr. Ohm insists on this.



Yep. Saves wire and is much simpler.

You are running the +12v through the cab just the same either way. There are some instances where it makes sense to switch the ground (that's why our e-fans are switched that way), but the fact that the entire automotive, aeronautic, and marine industries normally switch the hot should tell you something.

Draw your circuits out both ways and compare them.