Fuse sizes?

[patrickt]

1) See my thread on pushers and pullers: Cool Modification - For Pusher Fans Only, Though

2) Fans pull a variable amount of current depending on their conditions -- remember, they're electric motors not light bulbs. The long and the short of it (get it, short) is that so long as the fuse is less than the burn up current of your wiring then you will be protected. So long as it is not a fast-blow fuse, going above the max current is all you need. So, you have a wide choice of fuses without worrying about being wrong.

3) If you want to know the true current numbers, you have to put a gauge on your wiring (as per my thread) -- you can not rely on specs alone.

4) If you are grounding your fans to the frame, make sure that the path of the frame to the negative terminal of the battery is nice, clean, and of a fat gauge. If the negative battery cable runs to your block or head, you must be able to trace with your hands a fat gauge ground path from the engine or head to the frame, ie a fat ground strap, a fat ground wire, etc. In other words, pretend that the motor mounts, trans mounts, brake cables, and the like are all made of rubber and glass and provide no path for the return current. You must do this even in an aluminum car. Your fans will still run even with a half-ass grounded return path, but they will perform much better with a clean, high-gauge path. The ground path from the frame to the battery terminal is an often-overlooked problem -- correcting it makes everything on your car work better, your food tastes better, your dog smells better, and so on....

[patrickt]

Hmmm, thought I talked about my inductive ammeter in that thread, but it was on this link right here: 300 amp X 12 volt Circuit breaker

[rodneym]

Originally Posted by patrickt

1) See my thread on pushers and pullers: Cool Modification - For Pusher Fans Only, Though

2) Fans pull a variable amount of current depending on their conditions -- remember, they're electric motors not light bulbs. The long and the short of it (get it, short) is that so long as the fuse is less than the burn up current of your wiring then you will be protected. So long as it is not a fast-blow fuse, going above the max current is all you need. So, you have a wide choice of fuses without worrying about being wrong.

3) If you want to know the true current numbers, you have to put a gauge on your wiring (as per my thread) -- you can not rely on specs alone.

4) If you are grounding your fans to the frame, make sure that the path of the frame to the negative terminal of the battery is nice, clean, and of a fat gauge. If the negative battery cable runs to your block or head, you must be able to trace with your hands a fat gauge ground path from the engine or head to the frame, ie a fat ground strap, a fat ground wire, etc. In other words, pretend that the motor mounts, trans mounts, brake cables, and the like are all made of rubber and glass and provide no path for the return current. You must do this even in an aluminum car. Your fans will still run even with a half-ass grounded return path, but they will perform much better with a clean, high-gauge path. The ground path from the frame to the battery terminal is an often-overlooked problem -- correcting it makes everything on your car work better, your food tastes better, your dog smells better, and so on....

1) I agree with Chas on the 8 track.
2) Check. What I'm generally observing is that fuses are about 1.5x's the 'rated' current, and if there's no fuse of that size, it's bumped up. The Spal suggested fuse for the puller surprised me but according to your explanation, it seems ok. For now...
3) Check.
4) I'm good here.

Thanks.

[patrickt]

If the fuse doesn't blow, then it's the right size. Unlike a circuit breaker, which will blow at a lower current spec as it gets hotter. A 40 amp circuit breaker that is mounted to your firewall under the hood can easily blow at, say, 30 amps. The circuit breaker manufacturer has a chart that shows you about where it clicks off depending on how hot it is, but most car guys on here don't know that and just assume that 40 amps means 40 amps....