Switch wiring/relay questions

[45acpJr]

I've been getting ready to install my new DIY4x dash, but before I jump in to it I am trying to get my electrical in order. I am planning on doing relay mods on anything needed. As far as I know it;s just headlights, and cooling fans. Is there anything else I should be placing relays on? Next question is when wiring my switches I assume I can use a smaller low amperage switch on anything that is relay controlled, is that correct? Also when wiring these switches should I be running the hot thru it or should I use the switch to interupt the ground to complete the circuit?

 

[dremu]

I can use a smaller low amperage switch on anything that is relay controlled, is that correct?

Yep. Your average Bosch type automotive relay takes IIRC .07A (70mA) to run the coil, so basically any switch will work.

Also when wiring these switches should I be running the hot thru it or should I use the switch to interupt the ground to complete the circuit?

PLEEEEEASE for all of our sanities, switch the hot side. Switching the ground side will drive you nuts. Also, illuminated switches will get all messed up if you try that sh!t (by "all messed up" I mean "short the wrong way and pop fuses and make you angry.")

-- A

 

[Green69firebird]

Is there anything else I should be placing relays on?

I would put a relay on any load over 15 amps.

Next question is when wiring my switches I assume I can use a smaller low amperage switch on anything that is relay controlled, is that correct?

Yes, so long as the switch you use can handle the load of the relay.

Also when wiring these switches should I be running the hot thru it or should I use the switch to interrupt the ground to complete the circuit?

It really depends on what you are trying to achieve. I would use whatever is more convenient. Typically it is much easier to locate the relay on the + side.

 

[45acpJr]

Thanks for the reply, the reason I was asking about running the hot or ground thru the switch was because I am currently running the hot thru my switches that I wired up for my ignition and it works with no issues other than they are always warm. They are illuminated switches so I never figured out if they were warm because of the illumination or if they were not meant to run the power thru. I know you want to ask what amperage rating they are and I have no idea off the top of my head but they are large marine rocker switches.

 

[Fordum]

If you are firing a relay, and its small enough for you to pick up without a hoist, then the heat is from the lights........

 

[45acpJr]

Currently there isn't a relay those switches are handling a full load

 

[Fordum]

In that case, its still unlikely, but possible that the switches are warm from the load. They should have a current rating on them somewhere.
Unless it specifies, the rating is the switching rating, which is always lower than then holding rating.

In other words, if its rated for a 10 amp load, then that is the max it should be used to turn off and on due to arcing of the contacts.
But once its on, it will usually handle 15 to 20 amps continuous. But you should limit it to the 10 amps to keep from shortening its life.

And in either case, it should not be warm from the load.
To test it, there is usually a way to kill the light.
Some of the older style switches had replaceable bulbs, so you could just remove the bulb.
All of them require a ground wire for the bulb, either a separate wire or a contact that makes contact with the mount.
Disconnect that contact, and the bulb will not turn on.
Also, some models have a wire from the bulb to the load contact that can be unplugged.

 

[45acpJr]

Thanks fordum the troubleshooting was so obvious I looked right past that