Electrical protection ??

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Brooks James

VET, CPT, Huey Medevac Pilot
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I’m all about redundancy. I
Have set up all electrical items so that the fuses are slightly below the amperage of the item. I want to install a fuse or fusible link coming from the main out put from the alternator.
I’m thinking that my alt is 65 amps, will check, and installing a 70 or so fuse/fusible link.
Your thoughts??
 
Have you seen this?

MAD 3.jpg
 
It depends on the year and model of your car. The bulkhead connector is the weak link on the early cars, where all the alternator output was going through it to the ammeter. Crackedback sells a kit to remedy this.
 
It depends on the year and model of your car. The bulkhead connector is the weak link on the early cars, where all the alternator output was going through it to the ammeter. Crackedback sells a kit to remedy this.
Custom wiring no bulkhead
 
Your thinking is sound, IMO. Make sure you know the true output of your alternator, and your true load. If you have a DC ammeter, you can double check the true current draw of your car under full load, ie lights, wipers, AC(if you have it) and sound system turned up. I've been called "The safety sissy" for years, and I wear that title with pride.
 
Your thinking is sound, IMO. Make sure you know the true output of your alternator, and your true load. If you have a DC ammeter, you can double check the true current draw of your car under full load, ie lights, wipers, AC(if you have it) and sound system turned up. I've been called "The safety sissy" for years, and I wear that title with pride.
Thanks,
 
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I spent 22 years at Boeing, installing and trouble shooting electrical systems on many models of 747's, and the new Air Force KC46A Tanker.. Sometimes I go overboard with safety, but I won't change. Keep asking questions, it's not a sign of weakness, it's asking us old farts with experience so you don't make the same mistakes we survived.
 
As an ex Army helicopter pilot
Redundancy and safety are hard wired. We were trained to expect a major problem at any second. If the crew chief had said kiss my *** sir I would have said, once,or continuously . I was basically a well paid ambulance driver but the chief was the boss it was his job to keep the bird in air.
 
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Interesting schematic. I don't understand the 14 gauge link protecting the charge circuit nor the 16 gauge link protecting the dash feed. Are they not too light? And, why do you need the red and black wire spliced on the dash side of the bulkhead?
Answered my own question......Fusible links are spec'd 4 gauge numbers smaller than the wire they are designed to protect. Still don't understand the bulkhead splices though.
 
Interesting schematic. I don't understand the 14 gauge link protecting the charge circuit nor the 16 gauge link protecting the dash feed. Are they not too light? And, why do you need the red and black wire spliced on the dash side of the bulkhead?
Fusible links are not copper wires.
They are sized to overheat and melt FIRST in the event of continuous over-draw like a short-circuit; but will survive many momentary over-draws, so you don't get stranded on the hiway. A regular fuse here would pop in mere seconds or even milliseconds, leaving you no diagnostic time after the sun goes down, so then you are left stranded 'til morning.
I experienced a fusible-link meltdown once, early in the morning on the way to work. I just happened to have a fuse-holder in my emergency repair kit, so a couple of minutes later, it was installed and blowing fuses. I cut out the offending culprit, but it still required a 40A fuse to continue driving.
I fixed it a few days later, after work, by replacing the F-link and offending item.

F-links are just slow-blow fuses, sized to prevent large over-draws from setting your car on fire..... yet allowing momentary overloads to prevent you being stranded.
 
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The black "welded splice" is factory. The wire comes off of the ammeter and branches off that way.
I wired my car similar to that schematic BUT I stopped the red wire at the starter relay. My setup only has the black wire going through the bulkhead.
 
My setup only has the black wire going through the bulkhead
By tying the back and red together puts 1/2 the current through each effectively making one larger wire for powering the car.

If you were pulling 15 amps through a bulkhead connector and you then split the load between 2 bulkhead connectors each will only see 7.5 amps
 
Fusible links are not just a smaller gauge piece of wire. They usually have high temperature insulation to prevent a secondary short when they melt open. You want to maintain the insulation of the power to any nearby ground.
 
By tying the back and red together puts 1/2 the current through each effectively making one larger wire for powering the car.

If you were pulling 15 amps through a bulkhead connector and you then split the load between 2 bulkhead connectors each will only see 7.5 amps
I run an 8 gauge wire continuous through a drilled hole instead of using 2 12 gauge wires.
 
I replaced my fusible link with a maxi fuse, actually two of them due to the other changes I made to wiring. Started with one the TII FWD cars as they had multiple links in one unit and the fix to one of them blown was to cut the wire open and wire in a new link.
 
I'm hoping crackedback will chime in here soon. The fusible link acts like a slow blowing fuse, it'll absorb a high current spike for a bit longer than a fuse, which melts immediately after it's current has been exceeded(Harbor Freight fuses excluded). All our old Mopars had them from the factory. Slantsixdan is another excellent source of electrical information, if he's still around. He's also an expert on lights for our old Mopars. Try reaching out to either of these two gentlemen. They've helped me in the past.
 
I'm hoping crackedback will chime in here soon. The fusible link acts like a slow blowing fuse, it'll absorb a high current spike for a bit longer than a fuse, which melts immediately after it's current has been exceeded(Harbor Freight fuses excluded). All our old Mopars had them from the factory. Slantsixdan is another excellent source of electrical information, if he's still around. He's also an expert on lights for our old Mopars. Try reaching out to either of these two gentlemen. They've helped me in the past.

He is. Just tag him. He just responded to one of my inquiries the other day.

@slantsixdan
 
Thank You, slant. I was hoping you were still around.. I've found your lighting advice invaluable. Without you knowing it, you've helped me a bunch with my '70 Swinger 340. I might be a bit of a lurker, but I will chime in to acknowledge the sage advice I've gotten from this forum over the past decade, or so. You're the SME for lighting. Thank You.
 
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