Blowing Fuses

[Vic in E-TN]

On my friend's car, a mid '28 Phaeton with a Powerhouse generator, the car ran well for months at a time without blowing a 30 amp fuse. Saturday his car died about 10 miles from my house and proceeded to blow three 30 amp fuses in succession. The lights were not on and the brakes were not being applied. I hauled it back and followed all the wiring except the brake light switch wiring which was behind the battery. There was no evidence of frayed wiring or rubbing to the frame. I installed a 30 amp breaker in place of the fuse and the car started and ran perfectly and he drove it 25 miles home without incident.

The same thing happened last August and he replaced the fuse a few times until it worked.

I still do not know why the breaker worked where the fuse did not. Could it possibly have something to do with having a Powerhouse generator instead of a regular generator?

Vic

[Brentwood Bob]

Check the fuse holder. they are prone to shorting out due to poor construction. Also check the mounting screws. If too long, they contact the starter internals.
The posts of the fuse holder are poorly insulated.
Bob

[Mitch//pa]

A recent thread that may help
https://fordbarn.com/forum/showthread.php?t=217351

[Vic in E-TN]

The basic question still unanswered is - why will a fuse blow and a breaker will not ?

Vic

[Kurt in NJ]

It could be that the "short" is for a very short time, long enough to blow the fuse, but not long enough to heat the breaker and open it

[marc hildebrant]

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Fuses and circuit breakers come in many different types with the same amp rating. For example, a fuse can be a "slow" blow or a "fast" blow.

Marc

[captndan]

Circuit breakers are made for long term use. Not really made for multiple on off use. They do ware out. So, use fuses in your automobile.

[Dave Slater]

Replace the fuse with a headlight globe. Then every time the "fuse" blows the headlight globe will light up. Then you can start to troubleshoot. I found a brake light switch was temporally shorting out. After fixing the problem install the fuse back in the holder.

[Big hammer]

I just replaced a fuse in a neighbors riding lawnmower, I found that the battery was installed positive ground. Installed a new battery, replaced the blown fuse and all is good. Now why the blown fuse? What did the owner do to blow a fuse? Would hooking up a battery backwards cause a fuse to blow? Good luck with your problem of fuses blowing!

[JBill]

I use a 20 amp fuse. I know it's not the issue, but isn't a 30 amp fuse (or breaker) a little hefty?

[JBill]

Where did that underlining come from? Not me.

[Tom Wesenberg]

Originally Posted by Big hammer

I just replaced a fuse in a neighbors riding lawnmower, I found that the battery was installed positive ground. Installed a new battery, replaced the blown fuse and all is good. Now why the blown fuse? What did the owner do to blow a fuse? Would hooking up a battery backwards cause a fuse to blow? Good luck with your problem of fuses blowing!

The battery being installed with the wrong polarity most likely fed back through the diodes in the charging system and blew the fuse. Better to blow the fuse than the charging system.

[Big hammer]

Originally Posted by Tom Wesenberg

The battery being installed with the wrong polarity most likely fed back through the diodes in the charging system and blew the fuse. Better to blow the fuse than the charging system.

Thanks Tom I was thinking that also.