I'm reading the US NEC 2020 article 706 and trying to understand the required over-current protection needed between the battery and the inverter.

My understanding is that a disconnect is required outside the house by the electrical grid meter that disconnects both Positive and Negative cables. But this disconnect doesn't necessarily need to provide over current protection.

Inside the house, I'll have a breaker to provide over-current protection, but I'm not seeing if that protection applies to both cables or just the positive.

I've seen that UL listed LFP batteries have their own built-in breaker that only disconnects one of the cables. I'm thinking though, that if I had more than one battery, code requires a single over-current protection device for the whole LFP battery bank?

So to sum up: do I need an over-current device if the batteries already have one? And would it need to protect both cables or just one?

I'm reading the US NEC 2020 article 706 and trying to understand the required over-current protection needed between the battery and the inverter.

My understanding is that a disconnect is required outside the house by the electrical grid meter that disconnects both Positive and Negative cables. But this disconnect doesn't necessarily need to provide over current protection.

Inside the house, I'll have a breaker to provide over-current protection, but I'm not seeing if that protection applies to both cables or just the positive.

I've seen that UL listed Lithium Iron Phospate (LFP) batteries have their own built-in breaker that only disconnects one of the cables. I'm thinking though, that if I had more than one battery, code requires a single over-current protection device for the whole (LFP) battery bank?

So to sum up: do I need an over-current device if the batteries already have one? And would it need to protect both cables or just one?