2020 NEC and solar tap

[reader2580]

The 2020 NEC will now require an exterior emergency disconnect at the service. I have a solar tap that I need to redo. I believe it is considered line side because it is between the meter and my main breaker.

Does anyone know if I need to have the exterior emergency disconnect also disconnect the solar tap? Is it legal to place the solar tap between the emergency disconnect and the main load center?

[PVAndy]

Generally no. You need to run the inverter ac output to the exterior ac disconnect and then and back into the fused ac disconnect for the supply side connection. Is your a Rapid Shutdown compliant system?

BTW in New England all Utilities require external AC Disconnects and most require it to be within 10 feet of the Utility meter

Andy

[reader2580]

I have Solaredge so fully rapid shutdown compliant.

The exterior emergency disconnect is new in the 2020 NEC and is not solar specific. It shuts off service to the dwelling. Yes, I have to have a solar safety switch also, but that is separate.

[bcroe]

. BTW in New England all Utilities require external AC Disconnects
and most require it to be within 10 feet of the Utility meter. Andy

That could be very difficult, for example my inverters being in another building 270 feet
from the meter. The installer put the AC disconnects close to the inverters. Bruce Roe

[solarix]

Let me guess - another negligibly safer code rule pushed by the microinverter companies that happen to benefit from it....

[reader2580]

Let me guess - another negligibly safer code rule pushed by the microinverter companies that happen to benefit from it....

This is not a solar rule.

All single family dwellings, solar or not, will be required under the 2020 NEC code to have an exterior emergency disconnect on the main service for firefighters to shut off power to house in an emergency. I am trying to figure out if under the 2020 code I would need to have my solar line side tap protected by such a disconnect. Meaning, would I put the tap before or after this new disconnect?

My utility requires an exterior disconnect for my solar that is completely separate from this new NEC rule.

[badwithusernames]

Does the whole house disconnect do away with the need for a separate solar AC disconnect? Because shutting the whole house down will kill the inverter and activate the rapid shutdown. I would think that having too many disconnects could lead to the wrong one NOT getting switched. imagine off the solar was shut off and the main was not; its a good argument to have it all on one.

[reader2580]

Does the whole house disconnect do away with the need for a separate solar AC disconnect? Because shutting the whole house down will kill the inverter and activate the rapid shutdown. I would think that having too many disconnects could lead to the wrong one NOT getting switched. imagine off the solar was shut off and the main was not; its a good argument to have it all on one.

My question is if it meets the 2020 NEC to put my solar tap after the service disconnect. Could I use a meter base like below and put the solar tap after the breaker? I have read sections 230 and 690 of the 2020 NEC and didn't come away with an answer.

meterdisconnect.png
I would need to check with my utility if the requirement for the solar disconnect switch would go away. The utility's concern is being sure the solar is dead if they have to work on my service. The reality is that rapid shutdown would occur if power is disconnected by the utility, but they don't trust that.

[bob-n]

You want to meet NEC. You need to meet the approval of the agency having jurisdiction (AHJ), which is typically the city or town inspector. They may demand more or accept less. They may have a preference for a particular style of disconnect. I really think you need to talk with them and get them to tell you what to install.

In my town, these people are willing to talk with you before you start construction and tell you what you need. I simply walked into the town office Monday morning before people started on their field work, and asked to speak with an inspector. I showed the person my drawing, asked my questions, and left with 100% of the answers. It helps them to set you straight early because it saves them from denying your permit and having to inspect twice.

You mentioned that the utility crew wants to be sure that the lines are unpowered when they work on them. Rapid shutdown should satisfy that need, but any manual AC disconnect near the power meter will give them extra comfort.

Another concern is that firefighters want to be sure that the wires are unpowered if they need to attack your house with an axe. For the DC string, again, rapid shutdown should satisfy that need.

Your proposed meter box could be a good solution, but in my area, the public utility will not allow me to use a different style meter box. Start with the local inspector. They will know what the utility requires.

[reader2580]

Another concern is that firefighters want to be sure that the wires are unpowered if they need to attack your house with an axe. For the DC string, again, rapid shutdown should satisfy that need.

Your proposed meter box could be a good solution, but in my area, the public utility will not allow me to use a different style meter box. Start with the local inspector. They will know what the utility requires.

In Minnesota electrical inspectors are contractors on behalf of the state. Only the largest cities in the state employ their own electrical inspectors. The contract inspector who does inspections in my city doesn't like to help homeowners. If you can't tell him what section of the NEC pertains to the question he won't help. A lot of sections of the NEC are vague as to what is really allowed and I am trying to get clarification so I pass the inspection and don't waste my time and the inspector's time. The inspector should be able to say what is allowed.

The whole 2020 NEC exterior emergency disconnect rule is so new I think nobody really has a good answer on what is/is not allowed for the areas of the country that typically have the load center / breaker panel inside the house instead of inside. An electrician I know thinks a lot of manufacturers will be coming out with equipment to meet this requirement as more states adopt the 2020 NEC.

I do not have any solar on the roof of my house. My solar is on roof of detached garage and on a ground mount. All of my solar is moving to a ground mount.

I have talked extensively with my utility about what meter bases are allowed. It came down to any UL listed meter base with a heavy duty bypass is acceptable. I actually talked to the guy who reconnects/connects the power to a new meter base. He decides if the new meter base is compliant and told me any UL listed meter case with heavy duty bypass will pass.

[reader2580]

Let's take solar out of the equation here. This new emergency disconnect rule applies to any house, solar or not.

Let's say I have a meter base with a 200 amp breaker integrated into my meter base. Can I hook up my main load center and a sub panel after the 200 amp breaker by putting a tap in for the sub panel? (My solar actually has a two or three space load center because I have multiple inverters so my solar is technically a sub panel.)

[reader2580]

Here is a diagram of what I want to do. The sub panel is for my solar as I have two inverters.

[foo1bar]

I don't explicitly see the breakers for your subpanels.

But I'll assume that what you'll have is:

Utility line ==> meter ==> 200A main breaker ==> pair of 100A breakers within same box as 200A main ==> two sets of wires, each going to one of the multiple subpanels.

Note that I said multiple subpanels - your 200A breaker IS your main panel. I think normal nomenclature is that you have 1 main panel - anything else is a subpanel - including the subpanel that previously was your main panel and had all the breakers for your house. So what you have in this diagram as "main panel / load center" is not a main panel -it's a subpanel.

It might be possible to have a 200A breaker, and not have multiple breakers for the subpanels in your main panel - but you'd have to make sure you met all the rules for that type of setup, and I don't know what they are (or if it's possible under NEC rules.) I'm guessing it probably is possible, but breaker for each subpanel is easy and I think would be cheapest/easiest way to do things.

[bob-n]

I did some digging, and meter boxes like the one you show seem to be specifically engineered to meet NEC 2020 230.85 emergency disconnect requirements. So you're definitely on the right track.

How are you getting two wires per phase out of the meter box? That picture shows a breaker with a single screw output. Some meter boxes have provisions for secondary breakers, such as Milbank U5168-XTL-200. I'm sure that there are many other choices.

Keep in mind that large cables are not trivial to join and you certainly need excellent connections. Polaris and Milbank make good connectors to join large wires. But I don't know if they are permissible in a meter box. You may be better off with a meter box engineered for two connections per phase.

[reader2580]

I did some digging, and meter boxes like the one you show seem to be specifically engineered to meet NEC 2020 230.85 emergency disconnect requirements. So you're definitely on the right track.

How are you getting two wires per phase out of the meter box? That picture shows a breaker with a single screw output. Some meter boxes have provisions for secondary breakers, such as Milbank U5168-XTL-200. I'm sure that there are many other choices.

Keep in mind that large cables are not trivial to join and you certainly need excellent connections. Polaris and Milbank make good connectors to join large wires. But I don't know if they are permissible in a meter box. You may be better off with a meter box engineered for two connections per phase.

My plan would be to use Polaris connectors. I'm not sure the Milbank meter base has enough room inside for all the connectors and wires.

My concern with a meter main is the 120% bus bar capacity rule probably applies to it. I would go with a meter main if allowed.