Dumb Electrical Question

[Shoebox]

Ok, so fuses are rated by amps, not volts. So in the context of changing a car from 6v to 12v assuming none of the fused components draw more than the original fuses that are in place, all is good?


I do have all the bulbs switched to 12v, voltage drop device for 6v gauges and other components replaced by 12v equivalents,.... just had to ask this (dumb) fuse question. Thanks!

[tubman]

Actually, in amps, they draw less. Since 6 volts requires a larger gauge wire than 12 (higher amperage), it is more than adequate. I have heard that "the duty of the fuse is to protect the wire, not the component". The original fuses are sized properly for the wiring in the car, so they should be fine.

[Zeke3]

Fuses are sized to protect the wire harness, so if your harness has the wire sizes originally used with 6v system voltage you should be in good shape. If you reduced any wire sizes in the conversion to 12v, then you should review the fuse rating protecting that circuit.

[Shoebox]

Thanks guys for the quick response as I just had to ask the question, now I can put that concern aside. The car has all new Original style wiring harness, so all should be happy.

[solidaxle]

What these guys said. Just make sure no one installed larger fuses then necessary to protect the circuit. An internet search will give you what size fuse for the wire size.

[rotorwrench]

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16 gauge is the most common wire size and it takes a 10-amp fuse for protection. 14 gauge for larger draw circuits takes a 15 amp fuse. Voltage isn't relevant when it comes to wire size and it's ability to carry a specific amount of current.

A smaller amp rating fuse can be used on any circuit but don't use a larger amp rating than what it is designed for.

[JayChicago]

Changing the subject, but still is a dumb electrical question.

Watching one of the dumb non-reality restoration shop TV shows. The host guy finds a construction wire nut on a car and makes a drama scene about it. Says a wire nut is a fire waiting to happen because it won't stand up to vibrations in a motor vehicle.

I'm skeptical. My gut tells me if various automotive connectors were tested against a construction wire nut, the wire nut might win.

Anyone have any other thoughts about why wire nuts are a no-no on a car?

[B-O-B]

Size does matter!!!!

[solidaxle]

Originally Posted by JayChicago

Changing the subject, but still is a dumb electrical question.

Watching one of the dumb non-reality restoration shop TV shows. The host guy finds a construction wire nut on a car and makes a drama scene about it. Says a wire nut is a fire waiting to happen because it won't stand up to vibrations in a motor vehicle.

I'm skeptical. My gut tells me if various automotive connectors were tested against a construction wire nut, the wire nut might win.

Anyone have any other thoughts about why wire nuts are a no-no on a car?

I would say there's some truth to that. Besides looking cobby, I diffidently wouldn't use one under the vehicle exposed to the elements. I crimp or solder my connections, why ask for problems.

[Gene1949]

No such thing as a dumb question my friend. The responses were extremely informative as many of us have converted to 12 Volt.
I too had thought that the fusing was to protect the component rather than the wiring. I guess I must review my choices when I wired my car to the 2000 Ford Ranger fuse box, wiring and relays.

[rustedorrotting]

just sticking my 2 cents worth in. Wattage is voltage x current. So a 12 watt bulb as an example at 12 volts will draw 1 amp. The same bulb at six volts will draw 2 amps. So if the original wiring harness was rated for 6 volts, it will be twice as happy on 12 ie half the current.

[rotorwrench]

Wire nuts were made for building construction wiring where there isn't any appreciable movement after completion of the construction. Romex building construction wire is solid strand copper which doesn't fatigue as easy as multi strand automotive wire and carries higher amp loads as a general rule. Using a wire nut on multi strand copper is a lot like just twisting the wire together with the nut to hold it in twist. If it has to be disconnected for repair then the wire joint suffers the fatigue of that. Wire nuts can also collect moisture if the placement under a vehicle in a swampy area. The wire strands tend to wick moisture by capillary action so corrosion can also be a problem in some situations.

Motor vehicle wiring has always been designed with movement, vibration, and swampy environments as a factor. The real early automobiles that had no fuse protection and more wood construction used to catch fire and burn more often than more modern cars ever do and a lot of that is due to the changes employed by the Society of Automotive Engineers recommended practices over the years. Henry Ford was the SAE's first Vice President. Manufacturers and government officials recognized that safety was an important factor in the manufacture of automotive and aviation products so the American National Standards Institute or ANSI was also formed from all the separate manufacturing and engineering societies to give the necessary standards for safe practices.

If you really think about it, conductors have a starting point and a final destination. The wires have to be firmly attached anyway so a screw attachment with a locking device and solid terminals makes a good bit of sense. Look at the model A light switch and terminal box and think how a wire nut would work well in either location. I've seen wires wrapped around screws and tightened and it just doesn't look good or work well with future service in mind. Even a splice has to be able to function in all sorts of conditions without loosening or corroding. A person has to keep in mind the reason for the need for a splice in the first place.