Solar System G-N bond

[MisterMoSparky]

Then that would be the first disconnect for the solar system. Unless it isn't accessible with the meter installed? Weird.

I would have agreed until he mentioned the 70A breaker. Now I'm not sure.

I will have pictures here soon when I get back there today but it’s one flat head screw on the meter adaptor to access the breaker switch and the connections are 4 Phillips head screws away from accessing

 

[tortuga]

I'd just throw that meter adapter away and land the solar on a 70A breaker next to your surge protector.

 

[jaggedben]

I'd just throw that meter adapter away and land the solar on a 70A breaker next to your surge protector.

That'd require a 200A main breaker in the subpanel downstream.

 

[tortuga]

That'd require a 200A main breaker in the subpanel downstream.

Yeah if he does not have a 200A main inside I'd put one in, and while I am throwing stuff away I'd remove that divider as there is no underground service feed and simply nipple into the left side of the service panel.

 

[MisterMoSparky]

Updated photos of the complete setup

 

[MisterMoSparky]

I'd just throw that meter adapter away and land the solar on a 70A breaker next to your surge protector.

Would this not effect the way the digital meter reads how much power is being sent back into the grid and determine his electric bill?

 

[MisterMoSparky]

Yeah if he does not have a 200A main inside I'd put one in, and while I am throwing stuff away I'd remove that divider as there is no underground service feed and simply nipple into the left side of the service panel.

AHJ and POCO frown upon that in my area unfortunately. I have been many times needing that side of the meter only to LB - 45 - 90 + 10 more bends just to get a hole that’s right below the meter.

 

[MisterMoSparky]

Yeah if he does not have a 200A main inside I'd put one in, and while I am throwing stuff away I'd remove that divider as there is no underground service feed and simply nipple into the left side of the service panel.

There is a 200A Main Breaker inside

 

[tortuga]

Would this not effect the way the digital meter reads how much power is being sent back into the grid and determine his electric bill?

No its really just an adapter to make solar installs on old dilapidated services less costly (solar guy does not need to do a line side tap), you apparently just replaced the old service with a nice new one and with a 200A main in the panel and a 200A inside your good to get rid of it.

 

[tortuga]

AHJ and POCO frown upon that in my area unfortunately. I have been many times needing that side of the meter only to LB - 45 - 90 + 10 more bends just to get a hole that’s right below the meter.

Its removable with two screws, not necessary for the UL listing, and I've seen multi gang meter packs with bigger gaps inside the enclosure, AHJ you could argue with, POCO on the other hand no so much.

 

[MisterMoSparky]

No its really just an adapter to make solar installs on old dilapidated services less costly (solar guy does not need to do a line side tap), you apparently just replaced the old service with a nice new one and with a 200A main in the panel and a 200A inside your good to get rid of it.

That makes sense. Me and the lineman were wondering why they didn’t replace the service while they were at it but I believe they are not licensed electricians? I’m not sure how West Virginia is but many solar installs get put on outdated equipment. This specific homeowner asked us to put an RV plug in from his garage. Discovered his garage was fed off a 60Amp breaker and 12 AWG wire, then snowballed into his old General Switch Panel and his SE cable going up the side of his house was all tore apart.

 

[MisterMoSparky]

Its removable with two screws, not necessary for the UL listing, and I've seen multi gang meter packs with bigger gaps inside the enclosure, AHJ you could argue with, POCO on the other hand no so much.

This specific area of WV which, unfortunately is where most of my work is contained, have it out for us now because I would pull meters to replace panels when no disconnect was available. Other areas with the same POCO understood and would allow us to if needed especially in emergency situations but this specific area makes it their goal to provide as many obstacles as possible for us. We provided gifts to all the local POCO offices as a part of Linemen appreciation day and this specific office refused due to “policy”. I could go on but I feel the relationship is getting better but man I had to pull the meter today to replace the liquid tight and I honestly feared they were gonna come out and threaten to get my license taken away.

 

[ggunn]

Then that would be the first disconnect for the solar system. Unless it isn't accessible with the meter installed? Weird.

I would have agreed until he mentioned the 70A breaker. Now I'm not sure.

I took his word for it that there was a N-G bond in the Envoy box even though I did not see why Enphase would do that. Looking at the photo I agree that the blue box is some sort of device, and N and G are not bonded there.

As we have discussed many times, there are AHJs who still want N and G isolated in a line side connected PV AC disconnect, so possibly that is why the inspector unbonded them.

 

[wwhitney]

As we have discussed many times, there are AHJs who still want N and G isolated in a line side connected PV AC disconnect, so possibly that is why the inspector unbonded them.

Do these AHJs, if on the 2020 or 2023 NEC, recognize that this is in conflict with 250.25, and have therefore formally amended that section?

Cheers, Wayne

 

[ggunn]

Do these AHJs, if on the 2020 or 2023 NEC, recognize that this is in conflict with 250.25, and have therefore formally amended that section?

Cheers, Wayne

That's a good question to which I do not have the answer, although the main one I deal with has adopted the 2023 NEC. I just know what I need to do to get the system to pass inspection. Mine is not to reason why.

This isn't the only "special" rule that this AHJ has.

 

[jaggedben]

Here's an install manual for the ConnectDER socket adapter.

https://connectder.com/wp-content/uploads/2023/08/ConnectDER_Solar_MSA_v5.1_Installation-Manual-v1.0f.pdf

It appears to be a newer version but it seems unlikely that the basic design has changed.

The manual states there's a factory installed N-G bond. It tells you to land a neutral (only) in the meter socket and to the ConnectDER. Its j-box is removable, and has four pins that plug into the socket adapter, for a 4 wire connection. It also has the breaker in the bottom, which it claims is readily accessible. I'm still a little weirded out by considering that breaker a readily accessible service/PV disconnect, But supposing I accept that, your N-G bond is in the socket adapter and shouldn't be made again downstream. The manual doesn't quite come out and say that you can't leave out the green wire and make an N-G bond downstream, but it also doesn't say you can or even to ask your AHJ! Regardless, in our OP's case they landed a green wire in the ConnectDER j-box, which is bonded to the neutral there, so the inspector was correct to remove the additional N-G bond in the fused disconnect. And in fact I don't see why that fused disconnect is even necessary, assuming I accept the pretty-hidden-and-questionably-accessible breaker in the DER as the service/PV disconnect.

 

[MisterMoSparky]

I took his word for it that there was a N-G bond in the Envoy box even though I did not see why Enphase would do that. Looking at the photo I agree that the blue box is some sort of device, and N and G are not bonded there.

As we have discussed many times, there are AHJs who still want N and G isolated in a line side connected PV AC disconnect, so possibly that is why the inspector unbonded them.

I guess the area that I’m struggling with is in a normal dwelling when there’s a ground fault, the fault current travels through the equipment ground and returns to the neutral from the first disconnect bond, travels through the secondary neutral at the transformer which then eventually makes its way back to the breaker to trip. In this setup with the solar panels I see the EGC coming out of the 3/4” EMT. If there’s a ground fault for example inside the conduit does the fault current want to travel back to the transformer neutral or back to the solar panels? Either way I see the path for the EGC to take back to the breakers I just don’t understand what it’s “source” is that it needs to travel back to.

 

[MisterMoSparky]

Here's an install manual for the ConnectDER socket adapter.

https://connectder.com/wp-content/uploads/2023/08/ConnectDER_Solar_MSA_v5.1_Installation-Manual-v1.0f.pdf

It appears to be a newer version but it seems unlikely that the basic design has changed.

The manual states there's a factory installed N-G bond. It tells you to land a neutral (only) in the meter socket and to the ConnectDER. Its j-box is removable, and has four pins that plug into the socket adapter, for a 4 wire connection. It also has the breaker in the bottom, which it claims is readily accessible. I'm still a little weirded out by considering that breaker a readily accessible service/PV disconnect, But supposing I accept that, your N-G bond is in the socket adapter and shouldn't be made again downstream. The manual doesn't quite come out and say that you can't leave out the green wire and make an N-G bond downstream, but it also doesn't say you can or even to ask your AHJ! Regardless, in our OP's case they landed a green wire in the ConnectDER j-box, which is bonded to the neutral there, so the inspector was correct to remove the additional N-G bond in the fused disconnect. And in fact I don't see why that fused disconnect is even necessary, assuming I accept the pretty-hidden-and-questionably-accessible breaker in the DER as the service/PV disconnect.

The breaker was accessible from a hand removable screw. I guess it’s the same process as sliding the hinged cover off the meter combo to reach the main disconnect or opening the door to a panel.

 

[jaggedben]

I guess the area that I’m struggling with is in a normal dwelling when there’s a ground fault, the fault current travels through the equipment ground and returns to the neutral from the first disconnect bond, travels through the secondary neutral at the transformer which then eventually makes its way back to the breaker to trip. In this setup with the solar panels I see the EGC coming out of the 3/4” EMT. If there’s a ground fault for example inside the conduit does the fault current want to travel back to the transformer neutral or back to the solar panels? Either way I see the path for the EGC to take back to the breakers I just don’t understand what it’s “source” is that it needs to travel back to.

See what I said in post #11.

"As I said in the other thread, for grounding and bonding purposes it's best to completely ignore that energy will flow from the solar system to the service in the opposite direction of normal loads. The utility is still the source of major fault current and the only thing that will trip any breakers, since the solar output is limited to less than its overcurrent devices. All of the grounding and bonding safety considerations are the same as if the solar system was a load."

The solar is connected in parallel to the grid which means either or both sources can feed a fault on on the solar system circuits. The fault current will still flow through the N-G bond in the ConnectDER, and will still go back to the neutral center tap of the utility transformer. (From the center tap it can complete the circuit either directly, for utility sourced fault current, or through the other side of the transformer to get back to inverter.) For a typical residential service the available fault current from the utility is 100 to 1000 times more than from the solar, so if the utility is likely to trip the breaker in a fault when the solar isn't outputting current (say, at night) then it's just about as likely to do so when the solar is outputting current.

 

[tortuga]

In this setup with the solar panels I see the EGC coming out of the 3/4” EMT. If there’s a ground fault for example inside the conduit does the fault current want to travel back to the transformer neutral or back to the solar panels?

My understanding is if there is a line to ground fault in the AC output circuit of a grid tied inverter, say at the inverter housing, any current output by the inverter will flow back to inverter the shortest path it can take. So if the inverter can output a max of 56 amps and the fault happens in full sun when its putting that out, 56 amps will flow back to the inverter the shortest path it can take.
I suspect modern inverters will detect this condition rather quickly and disconnect themselves.

And likewise all the available current from the utility transformer will try to take the shortest path back to the transformer. In essence fault current flows on all possible paths back to its source.

As for the DC side if the inverter is putting out 56 amps @ 240VAC then you could have a DC side of say 20Amps @ 700 VDC or some similar high voltage/low current depending how the solar panels are stringed together, and I imagine the wire sizes on the DC side can carry a bolted DC fault continuously.
During a catastrophic bolted inverter AC side fault (say internal to the inverter) I don't think the DC side would see anything other than a large load.
I still think of the DC side of an inverter as a 'one way gate valve' isolated from the AC side, (there is no isolation transformer in a grid tied inverter) but I am no expert on inverter design. I imagine the isolation provided by the electronics of an inverter is equivalent to that of a transformer and what we think of as a 'Separately Derived System' though they are not considered that code wise.
I have never herd of a grid tied inverter failure mode where say fault current from the grid flows thru the inverter or high voltage DC flows out on the AC side, but obviously faults happen during accidents, storms and unforeseen events so anything is possible.