Solar tap via meter base adapter

[Terrier]

Meter-base adapters, that are inserted between the meter base and meter, have been available for a few years, providing a connection on the customer side of the meter for solar or vehicle chargers, without needing to find branch circuit space in the customer's main panels. While these may appear to avoid some costly main-panel expansions, do they meet all the NEC rules?

Most modern residential meter bases are rated 200 amperes, and most main panels have 200 ampere main breakers (that also serve as the service disconnect). The meter-base adapter adds another main breaker/service disconnect.

• the sum of the two separate service equipment overcurrent protective devices can now exceed the rating of the meter base. Is this permitted?
• the sum of the two separate service equipment overcurrent protective devices may exceed the rating of the service entrance cable, but this appears to be permitted by 230.90(A) Exception 3. Is using exception 3, allowing the sum of the over-current to exceed the rating of the service conductors, permitted?

In our area, most service equipment is indoors (basements), while the meters are outside. Using a meter-base adapter, with its own service disconnect, means the existing main panel disconnect (basement) and solar or vehicle charging circuit disconnect, are not grouped per 230.72, and do not meet the exclusion to grouping provided in 230.72(A) exception.

• Would the provisioning of a second service disconnect, not grouped with the existing service disconnect be permitted?

 

[jaggedben]

Meter-base adapters, that are inserted between the meter base and meter, have been available for a few years, providing a connection on the customer side of the meter for solar or vehicle chargers, without needing to find branch circuit space in the customer's main panels. While these may appear to avoid some costly main-panel expansions, do they meet all the NEC rules?

Most modern residential meter bases are rated 200 amperes, and most main panels have 200 ampere main breakers (that also serve as the service disconnect). The meter-base adapter adds another main breaker/service disconnect.

• the sum of the two separate service equipment overcurrent protective devices can now exceed the rating of the meter base. Is this permitted?

Yes. See next point.

• the sum of the two separate service equipment overcurrent protective devices may exceed the rating of the service entrance cable, but this appears to be permitted by 230.90(A) Exception 3. Is using exception 3, allowing the sum of the over-current to exceed the rating of the service conductors, permitted?

Yes, that's exactly what 230.90(A) Exception 3 actually says. It's important to realize that the exception is also dependent on a load calculation. That load calculation might be an issue if the meter adapter is used to add load (e.g EV charger), whereas a solar system does not add load. I'm not aware of these being used to add load and that strikes me as somewhat less legit since there are always other ways to add load to an existing service panel if the service size is sufficient and the only issue is breaker space (e.g. you can move circuits to a new subpanel). Article 705 often presents other limitations that solar systems have to get around that legitimize the meter adapter moreso as a solution.

In our area, most service equipment is indoors (basements), while the meters are outside. Using a meter-base adapter, with its own service disconnect, means the existing main panel disconnect (basement) and solar or vehicle charging circuit disconnect, are not grouped per 230.72, and do not meet the exclusion to grouping provided in 230.72(A) exception.

• Would the provisioning of a second service disconnect, not grouped with the existing service disconnect be permitted?

This again depends on whether it is being used to add a load (vehicle charger) or a solar system. 230.71(B) allows a separate disconnect or group of service disconnects "for each set of service entrance conductors permitted by 230.40 Exceptions 1,3,4 or 5." A load is likely not covered by those exceptions, but a solar system is covered by Exception 5, by way of 230.82(6). So, it's okay for solar, but not for a vehicle charger being added to the same structure on a single family home.

 

[ceb58]

I will bet anything that the POCO's are going to put a stop to these adapters. Some POCO's already have language that prohibits an extension of the meter. Some years ago they came out with the whole house surge protector that plugged in, good fast money for the EC's but the power company put a stop to it saying they would not allow the meter being pulled and plugged into the protector. Funny thing is they came back and offered to install one in the customers home for a monthly fee and could get away with it.

 

[jaggedben]

Of course no POCO wants you removing their meter without being part of the process. But I believe SDG&E actually was touting one of these for solar installations. Better than having people pull the meters to do supply side taps without asking, right? Of course they wanted charge a very uncompetitive fee for coming to put it in for you, just enough less than a service panel upgrade to make it slightly more attractive.