Electric fan fuse or breaker

[skip99]

Installing elect. Fan...should i use a 40a fuse or a circuit breaker? Why?

[Andy4639]

Originally Posted by skip99

Installing elect. Fan...should i use a 40a fuse or a circuit breaker? Why?

If you use a fuse and it blows you will have to change it. If you use a circuit breaker once it cools off it will reset on it's own.

[VetteVet]

I'm afraid that if you blow a 40 amp fuse or a circuit breaker you have got bigger problems. I think a breaker might work better like Andy said if it was a one time deal, but that much draw would probably mean a seized fan motor or a dead short in the power feed wire to the motor. Here 's a couple of diagrams with a 30 amp fuse. One has a manual override switch and the other with a light also wired in to show the fan is running.

[Andy4639]

VetteVet,
Just buy the switch that has the light built into it.

[skip99]

Originally Posted by VetteVet

I'm afraid that if you blow a 40 amp fuse or a circuit breaker you have got bigger problems. I think a breaker might work better like Andy said if it was a one time deal, but that much draw would probably mean a seized fan motor or a dead short in the power feed wire to the motor. Here 's a couple of diagrams with a 30 amp fuse. One has a manual override switch and the other with a light also wired in to show the fan is running.

Attachment 2071116


Attachment 2071115

Thats my point, everyone says a breaker is better because it will reset, but if the motor seized, wouldnt a fuse be better?
I know how to wire one, im actually using dakota digital controller, just not sure if to use fuse or breaker

[VetteVet]

Originally Posted by Andy4639

VetteVet,
Just buy the switch that has the light built into it.

Good point Andy, but the light in the switch would only show the fan running in manual override, when the switch was on. I think whoever made the drawing wanted to show the fan on anytime it was running.
I don't know if I'd want a light coming on and going off every time the fan cycled.

[Andy4639]

Originally Posted by skip99

Thats my point, everyone says a breaker is better because it will reset, but if the motor seized, wouldnt a fuse be better?
I know how to wire one, im actually using dakota digital controller, just not sure if to use fuse or breaker

The circuit breaker would just trip out and never reset I don't think in the case of the motor seized up.

[Andy4639]

Originally Posted by VetteVet

Good point Andy, but the light in the switch would only show the fan running in manual override, when the switch was on. I think whoever made the drawing wanted to show the fan on anytime it was running.
I don't know if I'd want a light coming on and going off every time the fan cycled.

Hard to tell by the drawing... but it's tied into 12 v in to the light and then 12 volts out to the over ride. So if the switch isn't turned on the light want be on will it? It looks like he wants it to tell him the over ride is on so he knows when to cut it off. Not very clear on that wiring schematic though.

[VetteVet]

Originally Posted by Andy4639

Hard to tell by the drawing... but it's tied into 12 v in to the light and then 12 volts out to the over ride. So if the switch isn't turned on the light want be on will it? It looks like he wants it to tell him the over ride is on so he knows when to cut it off. Not very clear on that wiring schematic though.

I agree with you that the drawing is not very clear. I shouldn't have posted it without explaining how the light worked. I keep forgetting that not everyone understands how wiring circuits work.





This is one of those times when the switching is done on the negative side of the circuit, Similar to the windshield wiper motor and the courtesy light in the cab.
In this case it's the relay for the fan, via the temperature sensor, and the over ride switch.

The OR switch doesn't need any positive voltage to trigger the fan relay. It does exactly what the temperature sensor does, only it does it manually. Why he shows the red positive wire to the switch is proof that the drawing is flawed. The red wire should go straight to the light to provide it with positive current, or it should go to 2 separate terminals on the switch.(single throw double pole)If he meant to show it with just the OR switch on, like you said. If you look closely at the the switch you can see that there is no terminal for the red wire there and it appears to be connected together.

The ground for the light is provided by the black wire from the relay which
is switched on by the temperature sensor or the OR switch. So the light will illuminate any time either one of those grounds the fan relay.