Wiring a relay

[GAmes]

I did a search, but perhaps this question is TOO basic , but here it is. When wiring a relay which wire gets a fuse? The input wire for the load or the input wire for the relay, or both??



TIA

 

[bighammer]

I usually just fuse the load line and not the relay. Not sure that is really correct though.

 

[crebelein]

i fuse both. the relay should only draw about 1/2 amp though so i usually run a 1 or 3 amp fuse. it's there just in case of a dead short.

 

[mikel]

What I usually do is a little different than most, but here it is since you asked.



I don't much care for switching the +12v to a relay because of issues with shorting out and the need for fuses on both leads. I'll usually take the fused +12v from the battery and run it to both the load side of the relay and one terminal on the coil. I'll run the other side of the coil through a switch to ground. Done this way you are just switching the ground, not power to the coil. This way a dead short in the activate lead will just turn on whatever the relay powers, and makes it pretty easy to figure out what's going on if you ever have to troubleshoot odd electrical issues.



Hope this helps,

Mike

 

[GAmes]

Thanks

I appreciate the prompt replys. I went ahead and fused them both..... cheap insurance

 

[Josparkz]

Originally posted by mikel

What I usually do is a little different than most, but here it is since you asked.



I don't much care for switching the +12v to a relay because of issues with shorting out and the need for fuses on both leads. I'll usually take the fused +12v from the battery and run it to both the load side of the relay and one terminal on the coil. I'll run the other side of the coil through a switch to ground. Done this way you are just switching the ground, not power to the coil. This way a dead short in the activate lead will just turn on whatever the relay powers, and makes it pretty easy to figure out what's going on if you ever have to troubleshoot odd electrical issues.



Hope this helps,

Mike

I like that idea , and a little less wire to run. In fact , I think the switched ground is the way a lot of stuff is done in vehicles these days . But will an illuminated switch still work ?

 

[mikel]

I like that idea , and a little less wire to run. In fact , I think the switched ground is the way a lot of stuff is done in vehicles these days . But will an illuminated switch still work ?

To be honest, I've never used an iluminated switch so I have no idea. I'd think that it might take a little care to make it work, but I think an illuminated switch could be made to work with a switched ground. But like I said I haven't use any illuminated switches so I'm not positive that it would work.



Sorry I can't be of more help.



Mike