Safety Switch

[Cudal81]

Hi, Do I still need the safety switch here? I have a load center with 150A main breaker. is the 150A main breaker considered as disconnecting means? Thank you

 

[electrofelon]

Maybe. You need overcurrent protection within 10 feet of the tap location. Also, some utilities require a visual load break disconnect for PV systems. That said, the solar industry does seem to have an irrational proclivity toward fusible disconnects. I actually have never used one for a line side tap.

 

[Carultch]

Maybe. You need overcurrent protection within 10 feet of the tap location. Also, some utilities require a visual load break disconnect for PV systems. That said, the solar industry does seem to have an irrational proclivity toward fusible disconnects. I actually have never used one for a line side tap.

Irrational proclivity?

I agree with your response that it is just OCPD in general that is needed, code-wise, to meet 705.11, or 705.31 in previous editions, but other factors commonly come in to play. I think the tendency to choose a fused disconnect over some of the alternatives is based on several factors. They may not necessarily apply to the OP, but they could apply in general.

1. The tradeoff of cost between an enclosed circuit breaker vs a fused disconnect, when necessary for it to be a separate device from the load center or panelboard. Either because of separate locations, or because of a preference to externalize the disconnect.
2. The ability to series-rate the fuses for protecting the breakers, when fault current is significant.
3. The ability to solve two problems with one solution, when the utility requires a disconnect with a visual break. This is commonly the reason for choosing a disconnect instead of a breaker, to meet this rule.
4. A separate disconnecting means has the advantage of completely de-energizing the entire panelboard, including the main wires that feed it. It is one way to meet 408.3(A)(2), such that the panel becomes a subpanel instead of a service panel, and can be de-energized upstream of it. Terminal covers work for meeting 408.3(A)(2), but there is a safety advantage to completely de-energizing it.
5. If there is any customer-owned metering, it will most likely need to be on the load side of a disconnect (cold sequence), and that would be a reason for an upstream disconnecting means.