Switch AND a fuse?

psimet

psimet

Senior Member
I put a whole new electrical system in my car last year. As a part of that I put one of the large disconnect switches in (mounted on the starter bolt and hiding under the steering column).

A couple of nights ago I was chasing a problem (ended up being the re-pop ignition was too large and causing the armored cable wire to short against the tank) and in that process of trouble shooting the armored cable came out of its position and the grommet moved enough that the cable touched one of the terminals in the junction box.

I saw a quick spark and told my son to hit the disconnect. It took him a second as...well he's 9. but even in those few short seconds that armored cable got blistering hot.

So...my question - even though I have the cut-off switch and I really wanted to keep everything looking as stock as possible... do many of you run the cut-off in addition to a fuse at the starter? If you do - do you find you pull the fuse when you stop or simply still use your cut-off switch?
 
The cut-off and the fuse serve different purposes. The cut-off saves drain on the battery and offers a convenient disconnect when doing repairs. The fuse protects the system against accidental grounding. The fuse *can* play the role the cut-off plays, i.e., remove it when parked or performing repairs to disconnect the battery, but (a) it's after the starter, so it's not really a complete disconnect, and (b) it's not designed for that, you add fatigue to the spring clamps every time you remove and replace the fuse. Eventually they'll get loose and then the fuse will pop out during driving... which ends your trip.

So yeah, I would run both. They do different things. You should not habitually pull the fuse as a disconnect.
 
alexiskai said:
The cut-off and the fuse serve different purposes. The cut-off saves drain on the battery and offers a convenient disconnect when doing repairs. The fuse protects the system against accidental grounding. The fuse *can* play the role the cut-off plays, i.e., remove it when parked or performing repairs to disconnect the battery, but (a) it's after the starter, so it's not really a complete disconnect, and (b) it's not designed for that, you add fatigue to the spring clamps every time you remove and replace the fuse. Eventually they'll get loose and then the fuse will pop out during driving... which ends your trip.

So yeah, I would run both. They do different things. You should not habitually pull the fuse as a disconnect.
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What alexiskai said. I have a 30 amp curcuit breaker where the fuse is. I also installed a 20 amp circuit breaker on my headlight/taillight circuits.
 
My '31 CCPU has a main disconnect and 3 fuses, a 30Amain fuse, a 20A fuse for lights and a 20A fuse for the horn.
 
Very happy with my fuse mounted on the starter. If I am not planning in using the car for a while, I remove the fuse.
 
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