I’ll try to keep this short I performed an inspection in May for one of my regular pre-listing realtors, (guess they’re just now reading my report?) She texted me today saying they’re in contract with a buyer but having a disclosure issue with our client, the seller, about the ampacity for the electrical service. Our client stated in disclosure that she is paying/paid for 400 amp service and they’re confused because my report states 200 amps for main service panel / disconnect and 100 amps for ADU sub panel / disconnect.
This system was unusual for me as it had two meters, as well as solar. In the pics, you’ll see a dual meter bank enclosure with the main home disconnect of 200 amps on top, and the ADU 100 amp disconnect below. The service panel on the left to the main home also had a 200 amp breaker on the top.
The dual meter bank enclosure states 400 amp bus / 225 amp branch. Would the ampacity rating of that bank be 400 amps or 225 amps? I did not mention that rating in the report, …should I have added something about the meter bank rating? As I said before, the only ampacity rating I put in the report was 200 amp for main service panel and 100 amp for ADU sub panel.
I want to make sure I’m reporting properly and would also like to help my realtor with her question, if possible. I told her to have the client call the POCO for confirmation but she’s still asking me. I thought the POCO bill might have the total service ampacity rating listed on the bill but I looked up my own bill and couldn’t find it.
Are you sure that the 100A panel is a sub-panel? There are three meter sockets (two with meters and one without a meter). It looks like you have two services, not one, and a dedicated solar backfeed (the socket on the left). The answer to your question is that it looks like you have a 100A and a 200A service. It wouldn’t make sense to have two meters and only one service. The separate building almost certainly has its own service with its meter being on the main structure.
Overhead outdoor taps are generally OK up to 100’. However, some jurisdictions do not permit overhead runs to detached structures, so you should check with the local inspection authority to see if the are any local restrictions on overhead feeds.
From my understanding, yes. A service disconnect breaker rated and labeled at 100 amps for the ADU was located at the dual meter bank feeding the ADU distribution panel. The distribution panel in the ADU was a MLO. My understanding is that a MLO distribution panel after the service disconnect is called a distribution panel / sub panel. Am I mistaken?
AND, did you not read my previous post where I stated that there were two services? I realize InterNACHI’s website is being updated right now. Maybe there was a glitch and my post didn’t make it to your computer?
That’s right. You are not mistaken. However, you juxtaposed your comment about the subpanel next to “Main panel” in your original post. It looked like you thought there was a main (Service) and a sub-panel downstream of it. Your comment would have been clearer if you had referred to two sub-panels instead of a main and a sub.
That is unless one has its service disconnect in its load center and the other had its service disconnect in the meter cabinet. That would be a very unusual arrangement. Based on what I can see in the photos, that doesn’t look like what you have. It looks to me as though you have two service disconnects in the same enclosure.
So, your use of “Sub-panel” is correct for the panel in the detached structure, but your use of “Main panel” to describe the other sub-panel is confusing.
A single service with two 200A panels in parallel would be a 400A service, but they would be supplied by a single meter. in this instance, there are two services with each being supplied by its own meter. That’s why it is not a 300A service, it’s a 200A and a 100A.
It probably would be clearer if you were looking at an older installation where there is a single tri-plex drop coming from the pole and supplying two sets of conductors with two masts going to two separate meter sockets and from the meter sockets to two service panels.
I see arrangements like that on old duplexes. There are houses in my area that started life as one big house, a mansion, then split into two or more dwellings many years later. They usually had small services for each unit. It was common to see 30A services when they were originally split. When I would rewire them, I’d replace the individual meter sockets with a multi-gang meter enclosure with a common mast or SE cable.
Outdoor service disconnects are rare in my area. However, some of the big houses that were split into multiple units provided some additional challenges compared to a building that was originally designed as a duplex, triplex, or quadplex. It was often necessary to place one or more units” panel far enough away from the meter bank to require an outdoor service disconnect.
The difference in the installation we are discussing here is that the meter housing and the service disconnects are combined in a single enclosure. That’s why I said in one of my earlier comments that it would be unusual to have only one service in the combination enclosure because there are two service disconnects. It would be confusing to the casual observer to see two disconnects but one of them being bypassed.
This is one of the most confusing NEC sections and IMO needs to be completely rewritten because it is very hard to navigate. In general a building of this type can only be fed by one service which is what is shown in the photo below because it does not meet one of the exceptions (A)-(D) below. The size of the service entrance conductors (those conductors after the service point) is calculated by the total calculated load of the structure. If the service point is the terminals at the meter enclosure then there are no NEC defined service entrance conductors as they are controlled by the utility company and not under the purview of the NEC. If the service point is at the transformer out near the curb or somewhere in between then the conductors feeding the meter enclosure would be the SEC’s. The utility company will typically define where the service point is (NEC definition below).
In this case the 200 amp and 100 amp circuit breakers are the service disconnects. So in answer to the question about service size from the information given it would be impracticable to determine an actual size. What can be determined is that there are two service disconnects, 100 and 200 amps. Here’s some information from Mike Holt as to when you would be permitted to have an additional service.
Number of services
There are many possible combinations of what is considered one service drop or one service lateral. A building can be served by only one service except as permitted by 230.2(A) through (D).
(A) Special Conditions. Additional services are permitted for the six reasons listed in 230.2(A). These include fire pumps and emergency systems.
(B) Special Occupancies. Additional services are permitted for either multiple-occupancy buildings where there’s insufficient space for supply equipment accessible to all occupants, or a building so large that one service doesn’t cut it.
(C) Capacity Requirements. Additional services are permitted for buildings with capacity requirements exceeding 2000A, or if the load requirements of a single-phase installation exceeds the serving electric utility’s power capacity.
(D) Different Characteristics. Additional services are permitted for different voltages, frequencies, or phases but also different uses such as varying electricity rate schedules.
If a building has more than one service, a permanent plaque or directory must be installed at each service disconnect location indicating the location of other services supplying that building [230.2(E)].
Service Point.
The point of connection between the facilities of the serving utility and the premises wiring.
Informational Note: The service point can be described as the point of demarcation between where the serving utility ends and the premises wiring begins. The serving utility generally specifies the location of the service point based on the conditions of service.
I performed an inspection in May for one of my regular pre-listing realtors, (guess they’re just now reading my report?) She texted me today saying they’re in contract with a buyer but having a disclosure issue with our client, the seller, about the ampacity for the electrical service. Our client stated in disclosure that she is paying/paid for 400 amp service and they’re confused because my report states 200 amps for main service panel / disconnect and 100 amps for ADU sub panel / disconnect.
