extended cranking trips 100 amp breaker

[Cool Beans]

Hiya!

Always size your fuse/breaker to the wire being protected, not the load being drawn. Ie, don't put a 150 amp fuse on #4 cable. . .#2 or larger.

Also, easiest way to meet the minimum 7" requirement is with one of these:

http://www.overtons.com/modperl/product/details.cgi?pdesc=Blue-Sea-Terminal-Fuse-Block-MRBF-1-Terminal-Stud&i=85269&r=view&utm_medium=cpc&utm_source=googlebase&s_kwcid=googlepla&cvsfa=2587&cvsfe=2&cvsfhu=3835323639&kpid=85269&gclid=CKX3hvvI9MQCFUxo7Aod1R8AbQ

BTW, great place to get custom made boat cables:

https://www.genuinedealz.com/

On my boat I have the positive post fused, then a short run to my 1/2 switch. . .then to the starter. Entire run is #2 and is protected, bazinga!

[sastanley]

What? Oh crap...now I gotta check that. I have 4# cable. Maybe for the starter run, and the battery to 1-2-both/150A breaker I need to move up to 2#??? The run is ~12 ft.

Thanks for the info CB, the boat had stiff 4# cable so I replaced it with same...except used welding cable, which is smaller gauge wires packed in the sheathing and much more flexible than the garbage from 1977.

+1 on genuinedealz.com - that is where I have gotten about 90% of my electrical stuff!!! I really like their shrink wrap termination fittings. They are awesome.

[BunnyPlanet169]

Shawn: I've found this chart useful

http://www.westmarine.com/WestAdvisor/Marine-Wire-Size-And-Ampacity

Watch out for voltage drop over longer runs, especially high current runs. It will drive a positive feedback loop - the more the voltage drops, the higher the current needs to be, the more the wire heats... I sized all my wiring for 3% or less, but that means bigger cable$.

Welding cable and diesel locomotive cable is great stuff, but doesn't have individual strand tinning for corrosion resistance. That's why marine UL1426 cable is so expensive.

[joe_db]

I wouldn't get too worked up about it. A load that might draw a continous 150 amps is one thing, but the starter draws about 120-130 amps for 20 seconds. A dead short will draw 300-1,000 amps or so and blow the breaker. 2 gauge is better for a starter than 4 gauge if you do feel like replacing it, but I would not say it is critical to do in the next day or two

What? Oh crap...now I gotta check that. I have 4# cable. Maybe for the starter run, and the battery to 1-2-both/150A breaker I need to move up to 2#??? The run is ~12 ft.

Thanks for the info CB, the boat had stiff 4# cable so I replaced it with same...except used welding cable, which is smaller gauge wires packed in the sheathing and much more flexible than the garbage from 1977.

+1 on genuinedealz.com - that is where I have gotten about 90% of my electrical stuff!!! I really like their shrink wrap termination fittings. They are awesome.

[joe_db]

If you do use welding cable, use closed end lugs and heat shrink them. You do not want water wicking into the untinned copper cable and ruining it.

Shawn: I've found this chart useful

http://www.westmarine.com/WestAdvisor/Marine-Wire-Size-And-Ampacity

Watch out for voltage drop over longer runs, especially high current runs. It will drive a positive feedback loop - the more the voltage drops, the higher the current needs to be, the more the wire heats... I sized all my wiring for 3% or less, but that means bigger cable$.

Welding cable and diesel locomotive cable is great stuff, but doesn't have individual strand tinning for corrosion resistance. That's why marine UL1426 cable is so expensive.

[Cool Beans]

I should apologize, didn't mean to worry you, lol. . .I thought all wiring should be 3% on a boat, which is what I have sized all my rewiring for so far. . .

As a comparison, the repro cables for my mustang are #4 and are turning over a 289 and no fuse