Circuit Protection for the AC Input To a Battery Charger


Hello, I am hoping to get an expert opinion on a very important electrical issue. I need to replace my battery charger. The AC is wired directly, but the unit I bought, as many are, uses a 3 prong plug. I spoke to my surveyor about how to properly wire the AC to the charger. He advised to connect the wires (snip the 3 prong head) via butt connectors and junction box. House power is 30 amp, the unit is 20 amp. Instead of direct wiring the power lines, shouldn't I use an in-line fuse? Would appreciate your input. Regards, Michael


Hi Michael, your hunch is right, a battery charger installed aboard your boat needs to be connected to a circuit breaker to protect both the AC line to the charger and the charger itself. To meet ABYC code, you should install a main double-pole breaker for the 30 AC main and then a single 20 amp breaker for the battery charger.  Consider the following:  or  - Jeff

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