In-line fuse or fusible link

[48caddymn]

I'm going through the wiring on my 1948 Cadillac project and want to add a few fuses to protect the wires from any future mishaps.  It appears the thermo-breaker on the light switch is supposed to protect most of the wiring if a problem arises.  I would like to put either a fusible link or a in-line fuse with a 30 or 40 amp fuse down near the starter where the main power wire feeds the entire car.  What would be the best method; a fusible link or an 8 gauge in-line fuse holder with a 30 or 40 amp fuse?  Since the car is not in running condition yet, I'm not sure how may amps the power feed wire from the starter post usually will carry.

I also would like to add 15 amp fuses from where the headlight and taillight power feeds come off of the light switch to protect all the wires running to the front and rear of the car if that makes sense?  And advise or guidance would be welcomed. 

Dan

[J. Gomez]

Dan,

I’m not an expert on your year and model so my comments would be mostly in general terms to your electrical topic. Other experts with the same year and model may chime in.

Placing a fuse in-line with the source is always a good idea. However dealing with the headlight switch you would also need to consider the load from all of the lights sources.

The main issue you may be looking at is to protect the circuits and the most important to also protect the headlight switch.

The best option is to encompass both, to off-load the headlights from the main power source at the switch and to protect the rest of the circuits left on it.

The solution for the headlights is to add a relay (6V in you case) that would operate from the headlight switch and power for the headlight would be from a separate fused source via the relay contacts.

The rest of the light would be power from the switch as they were and the circuit breaker will protect that path. As an extra safety step you could add an in-line fuse on the main input power feed for extra protection.

I do believe these type of modifications would be considered as safety in case you want to participate in any judging tournament.

Good luck..!

[Jay Friedman]

John Washburn (of Washburn's Wisdom in the Self Starter) recommends mounting a Standard 41-50 amp Voltage Regulator Fuse, VRP-21, on the B(AT) terminal of the voltage regulator to protect the wiring.  I've done this on my '49.  There are 2 such fuses for sale at this moment on ebay:

http://www.ebay.com/itm/Lot-of-2-Standard-Blue-Streak-Heavy-Duty-Voltage-Regulator-Fuse-VRP-21-/361014115032?hash=item540e1e3ad8:g:9bQAAOSwVFlT4RMr

[bcroe]

I'm going through the wiring on my 1948 Cadillac project and want to add a few fuses to protect the wires from any future mishaps.  It appears the thermo-breaker on the light switch is supposed to protect most of the wiring if a problem arises.  I would like to put either a fusible link or a in-line fuse with a 30 or 40 amp fuse down near the starter where the main power wire feeds the entire car.  What would be the best method; a fusible link or an 8 gauge in-line fuse holder with a 30 or 40 amp fuse?  Since the car is not in running condition yet, I'm not sure how may amps the power feed wire from the starter post usually will carry.
I also would like to add 15 amp fuses from where the headlight and taillight power feeds come off of the light switch to protect all the wires running to the front and rear of the car if that makes sense?  And advise or guidance would be welcomed.  Dan 

My own experience is older fuses are unreliable in the long run, and may cause excess
voltage drop early on.  At the least they should be used in a water proof holder.  I prefer
trouble free (for me) fusible links, which take little space.  The wire is available to make
your own.  Bruce Roe

[76eldo]

Bruce,

What do you think about using a circuit breaker?  Hess and Eisenhardt used to grab voltage right at the battery for the convertible top and windows.  They installed a big circuit breaker under the dash on a bracket.  That protects the wiring and the top/window circuit which is a big draw.

On my cars, I moved the breaker to a spot under the hood much closer to the battery.  That way if there is a short the breaker protects all the wiring under the hood and dash on that circuit.  The way they did it was wrong.

Brian

[bcroe]

Bruce,  What do you think about using a circuit breaker?  Hess and Eisenhardt used to grab voltage right at the battery for the convertible top and windows.  They installed a big circuit breaker under the dash on a bracket.  That protects the wiring and the top/window circuit which is a big draw.

On my cars, I moved the breaker to a spot under the hood much closer to the battery.  That way if there is a short the breaker protects all the wiring under the hood and dash on that circuit.  The way they did it was wrong.   Brian   

There are those sealed breakers with the same tabs as a fuse.  Seem to usually be a 30A. 
I haven't used many, but they seem to be OK.  I would most worry about corrosion on the
tabs, esp if under hood.  Some have bolts, pretty reliable.  Bruce

[76eldo]

The Eldos of that vintage have a little red box under the hood on the right fender well which has a post for a wiring junction point. I took a second box from a parts car and put the breaker in that.

It's the square type with the two posts.

Brian

[48caddymn]

Thanks for all the replies!  I think I will use the a waterproof 8 gauge fuse holder with a 40 amp fuse I found and splice it in down near the starter. I'm not concerned about the authenticity of the car since it will be just an unrestored driver.