Fuse question

[mikew66]

I just finished installing an LED aux. backup light on the expy. I used an "add a circuit" and tapped into the horn fuse. That is a 20 amp fuse. The add a circuit has a place for an additional fuse. What size fuse should I use in addition to the 20 amp fuse that was already there?

Also, what size fuse should use from the relay to the battery?

The light is a 27w LED light. The switch I am using is a 20 amp switch.

Thanks!

 

[stamp11127]

Depending on what voltage you use to calculate the amp draw, 12 or 14, that will use 1.9 - 2.25 amps. Use a 3 amp max.

 

[mikew66]

Thanks for the info. What about the inline fuse that goes from the relay to the battery? What size should I use on that one?

 

[stamp11127]

Since the fuse will be 3 amp and the switch is rated for 20 amp. what is the purpose of the relay? Your not needing to control a heavy draw.

If you can, post a schematic of how this is wired, make and model of the add a circuit.

 

[mikew66]

Yeah that's true. Just after doing a lot of googling, most people said to use a relay "just to be safe." In my very limited knowledge of the 12v system, I just went ahead and used a relay.

 

[stamp11127]

What is the rating on the relay and what gauge wire did you use on the load side?

 

[mikew66]

What is the rating on the relay and what gauge wire did you use on the load side?

I'll have to check. I'm pretty sure it's 25 or 30 amps and the wire is 12, I think. Either 10 or 12.

 

[stamp11127]

If that is correct & depending on the length of wire you should be safe with 15-20 amps. If and when you add to the circuit the hand test never fails. Hold one of the load wires a d see how warm it gets with the load on. If you get need the point of "damn this is getting pretty warm" the load is too high. Redneck circuit testing at it finest....

 

[mikew66]

If that is correct & depending on the length of wire you should be safe with 15-20 amps. If and when you add to the circuit the hand test never fails. Hold one of the load wires a d see how warm it gets with the load on. If you get need the point of "damn this is getting pretty warm" the load is too high. Redneck circuit testing at it finest....

Great. Thanks for the help!