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post #7 of Old 12-05-2010
Maine Sail
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Originally Posted by hellosailor View Post
"I have run 2/0 cables from the windlass directly to the house bank, with a 110 amp breaker in the feed."
You might want to doublecheck that. If you were to have a crowbar short at the winch (i.e. drop a crowbar across the power cables) and full battery power were to run in the cables through a dead short, it might weld the breaker shut instead of tripping it. Most common 12V breakers will weld shut and fail at something like 3300 amps, which even a common "automobile" battery can put into a dead short on a heavy battery cable. The breakers designed for higher loads (for direct use in battery cables) are often over $100 each. If you're already using one of those "nevermind". Otherwise, you might want to use an ANL fuse in that line as well.
This is good info and one reason to use ANL's, MRBF's or Class T fuses rather than breakers. I rearely if ever install thermal breakers in large loaded items directly connected to a large house bank.

The amperage interrupt rating (AIC) of the fuse or breaker used should exceed the banks cranking amp capacity. For instance three group 31 12V deep cycle batts can easily supply over 3000 CA at 70F. Many cheap breakers are a 3000 AIC rated product. You have to spend more money to get breakers that have a 5000 AIC rating. ANL's are 6000 AIC, MRBF's are 10,000 AIC and Class T fuses are 20,000 AIC rated.

-Maine Sail / CS-36T

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