Should I add a fuse?

I installed the fuse from Bill in CT (mentioned by Chris in WNC)
Works great. Joop


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steve s said:
What does your ammeter read when you have the headlights, turnsignals, and dashlight on, step on the brakes, and hit the horn all at once? A lower rated fuse will convert the normal brownout-with-horn-grunt under these conditions to a total blackout. Ten amps won't make it.
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Who says everyone is running all this stuff at the same time. You might as well convert your car to 12 volts w/alternator. I've run 10 amp safety fuses for 30 years day and night and never blew one unless I had a shorting problem.
 
Steve Ciccalone said:
Who says everyone is running all this stuff at the same time. You might as well convert your car to 12 volts w/alternator. I've run 10 amp safety fuses for 30 years day and night and never blew one unless I had a shorting problem.
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You are doing it right.

Run the smallest fuse that works for you and the way you drive. If you blow it and there was not a problem (just simple overload -- too many things on at once) put in a slightly larger fuse and keep going. Carry a spare of the size you normally use and carry one that is slightly higher.

The main downside of using a single fuse is that, if it blows, you will be dead in the water until you get it replaced. This can happen at very inconvenient or dangerous times. So you don't want the fuse to be too small (blow too easy).

The main power supply wires on an A are 12 gauge, which can safely carry 30 amps. The rest looks like 14 ga or 16 ga, I believe, which 30 amps is really overloading. But the main thing that will push you that high will be a short (some wire chafes through to ground, things like that) in which case it will go way above 30 amps really fast and the fuse will save even the smaller gauge wire before it fries. If you plan to have a single fuse and don't feel like experimenting, a 30 A should do.

I had a repro brake light switch short out on me one time when I hit the brakes. The 30 amp fuse blew and the engine died. I am so glad I had that fuse. It took a few minutes to disconnect the brake light switch and drive home carefully with no brake light, but so much better than having the car towed home after the wiring burned up.
 
Steve Ciccalone said:
Who says everyone is running all this stuff at the same time. You might as well convert your car to 12 volts w/alternator. I've run 10 amp safety fuses for 30 years day and night and never blew one unless I had a shorting problem.
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Steve,

I'm very happy for you, but I don't know you do it. The fact that the ammeter goes up to 20 is a clue. Headlights alone take close to 10 amps; ignition takes a few amps; dash light one or two; tail lights take a few; brake lights take more than the tails; the horn six or seven. Maybe a really really slow blow fuse? Having experienced the night-time brownouts-with-horn-grunt in my youth, as well as having smoked a lot wires messing around hooking things up, I take comfort in my fuses and knowing I can hit the horn and brakes at night if I need to without everything going dark and the motor dying.

Steve
 
While driving my A to the Post Office one day, the fuse blew and engine died. Thought was the repro brake light switch that I had modifed since it gave me problems before reworking with sleeves on front and back of housing. Disconnected the brake light wire and fuse blew immediately. Found that while installing the upholstry had driven a tack through the wire going to the dome light. This wire ran under the dash and up a door post. Car had been restored a year or so before this short appeared as the head of the tack was covered by metal piece along side the windshield and finally rubbed through the paint on the back of the metal. Glad I had the fuse as a fire could have resulted. Also put a tie wrap around the fuse so it is easily removed and can hide the fuse by the engine mount. If anyone tries to steal will not start without the fuse and very little possibility of draw down on the battery.
 
Definitely add a fuse. I used a simple in line plastic fuse holder, painted flat black and installed it in the wire coming off of the starter switch. Use enough wire so that you can tuck the fuse down between the starter and the block. The fuse is no longer in view and easy to service. Ed
 
Sturgis, you mention a circut breaker near the power source. I looked at O'Riley's for an inline one after an earlier post and couldn't find one. How about protecting the lights/horn or do you tie it in before them? I put a waterproof blade fuse (25a) at the starter.
Pete
 
Charlie Stephens said:
I was trying to convince a friend that he should add a fuse. I wasn't having much luck. As we closed the garage door I told him I thought I saw smoke. He thought I was joking. I made him open the door and we found a short in his wiring that was moments from bursting into flame.

Charlie Stephens
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That should be a good enough answer for ANYONE to add a fuse block to their car :)

Neal
 
Re: Should I add a fuse?--the rule of smoke applies here

Basic Electrical Engineering will tell you this: (Called the Rule Of Smoke)

All wiring and wires come with smoke built into them. It is always done at the factory.

It is put between the wire and the covering.

IF there is a short in the wiring and there is no fuse to protect the wires...the smoke comes out of the wiring. Sometimes at the end, sometimes the cover ruptures and the smoke pours out everywhere.

It is impossible to put the smoke back into the wires. Once the smoke is out of the wires; the wiring is pretty well shot.

And so may be the car.

Dennis L Oberer
Still alive but struggling in Green Bay WI
 
Re: Should I add a fuse?--the rule of smoke applies here

Dennis L Oberer said:
Basic Electrical Engineering will tell you this: (Called the Rule Of Smoke)

All wiring and wires come with smoke built into them. It is always done at the factory.

It is put between the wire and the covering.

IF there is a short in the wiring and there is no fuse to protect the wires...the smoke comes out of the wiring. Sometimes at the end, sometimes the cover ruptures and the smoke pours out everywhere.

It is impossible to put the smoke back into the wires. Once the smoke is out of the wires; the wiring is pretty well shot.

And so may be the car.

Dennis L Oberer
Still alive but struggling in Green Bay WI
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I like this.
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I always wondered how that worked!
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I extend the hot wire so I can pass it through the terminal box and firewall to the back of the firewall. I install an inline fuse and another wire extension to run back through the firewall and terminal box to the terminal stud. The wire inside the firewall can be pushed up between the firewall and the gas tank, out of sight. I don't like to see visible nonstock stuff in my engine compartment.
 
Peter J said:
Sturgis, you mention a circut breaker near the power source. I looked at O'Riley's for an inline one after an earlier post and couldn't find one. How about protecting the lights/horn or do you tie it in before them? I put a waterproof blade fuse (25a) at the starter.
Pete
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I have the fuse on the starter that I bought at Burt's.The circuit breaker is on the generator out put. I used a blade type in line fuse holder and stuck a circuit breaker in, instead of a fuse. I shut the engine off one day and heard this clicking noise. I could not figure what it was and finally realized it was the circuit breaker. I can remember where the short was now. This was a few years ago-maybe ten. The guy at the parts store showed me the trick of using a circuit breaker in the in line blade type fuse holder. I hope to get the "a" out today- finally got a rain free weekend. I will be glad when global warming comes back and the global cooling ends. We have had two days where the temperature has been above seventy this spring.
 
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