Mounting a DC subpanel in a truck

[texas taco]

I just purchased a Blue Sea fuse panel for my dbcab taco. The panel is rated at 100 amp. I am an electrician, but my DC theory is a little rusty. We use #4 for 100 amp things.. It seams that the wire for things in my factory harness are over fused " by the judge of wire size .which is a big no no in my line of work. Do i need to run #4 to my panel or do you think #6 would do. Or i guess what i am asking is can i fuse #6 at 100 amps DC or go with #4 Which seem way over kill? What are you all with these panels running to feed it? I am going to run an Engle, some lights a ham and maybe some misc things.
Sorry to be so long winded by the way...

 

[Robthebrit]

#6 is about the smallest you can safely and reliably put 100amps through. Which cable you really should use depends on how long your runs are, larger cables are used for longer runs, 12V suffers much worse from voltage drop than 110 or 240. For a given amperage through a given wire the volt drop is constant regardless of voltage but a 2v drop in 110 is irrelevent but for 12 volts dropping 2v is 16%. This problem is compounded because 12v systems usually involve high currents.

Running at 100Amps, with #6 you can run about 6 feet with a 4-5% volt drop, #4 about 14 feet, #2 about about 20 feet.

On this same subject: The number of winches I have seen badly wired is startling. Then the people complain the winch is not as good as it should be and because the wires are getting hot its obviously working very hard! Every winch should have next to zero volt drop on its wires at full load.

Rob

 

[RoundOut]

#6 is about the smallest you can safely and reliably put 100amps through. Which cable you really should use depends on how long your runs are, larger cables are used for longer runs, 12V suffers much worse from voltage drop than 110 or 240. For a given amperage through a given wire the volt drop is constant regardless of voltage but a 2v drop in 110 is irrelevent but for 12 volts dropping 2v is 16%. This problem is compounded because 12v systems usually involve high currents.

Running at 100Amps, with #6 you can run about 6 feet with a 4-5% volt drop, #4 about 14 feet, #2 about about 20 feet.

On this same subject: The number of winches I have seen badly wired is startling. Then the people complain the winch is not as good as it should be and because the wires are getting hot its obviously working very hard! Every winch should have next to zero volt drop on its wires at full load.

Rob

What is the current draw on a Warn 9000 lb winch? The Warn wiring harness kits for their multi-mount come with some pretty stout wire, I think it is 2#.

I have a dual battery system that I am fixing to relocate to the rear of my truck under my bed where the spare is normally kept. I was going to run three cables of 2/0 or larger back there for the two positive leads and one negative lead, also running a shorter ground to the frame back there.

Like Texas Taco, I was planning an auxiliary fuse panel, and would require making a decision similar to his, providing power to that panel. Surely the winch comes with its own inline fuse?

On the fuse blocks I have found, the individual circuits are max 30 amp. I cannot imagine a simple 30 amp fuse would be enough for a winch. Also, the fuse blocks that I have found have the push-on connectors which won't accomodate wire guages larger than 10, in most cases.

 

[texas taco]

Well it looks like #4 welding lead it is. Has any one used one of those 100 amp breakers that Sierra Expeditions sells? It looks like a good unit. Thanks for the info....

 

[flyingwil]

The 100 Amp CB would suit the Fuse Block perfectly. I know Wilman just got one not too long ago, you can try and PM him if he doesn't see this first. They are pretty HD, and waterproof... but I'll let someone that doesn't sell them chime in.

 

[Robthebrit]

What is the current draw on a Warn 9000 lb winch? The Warn wiring harness kits for their multi-mount come with some pretty stout wire, I think it is 2#.

I have a dual battery system that I am fixing to relocate to the rear of my truck under my bed where the spare is normally kept. I was going to run three cables of 2/0 or larger back there for the two positive leads and one negative lead, also running a shorter ground to the frame back there.

If you stall the motor you'll probably hit 500+amps. A couple of 2/0s will be fine. Be careful wiring the negative to the frame as the battery to frame connector has to suitably sized for the winch power vs its length.

Rob