3 wire feeder tap Solar; ATS, remote meter/main

[darunedefig]

I was granted permission to do a feeder tap by the AHJ.
I have concerns about making sure there is a proper ground to neutral connection.
There is a remote post mounted meter/main combination panel that is rated at 200 amps.
From the feed through lugs the wire goes to a 200A Generac ATS inside the house. (see images for example)
The L1,L2, Neutral three wire feeder is in a nonmetallic conduit to the ATS in house.
The remote Meter/Main panel has a ground to neutral connection. GEC to ground rod next to post.
The ATS has a ground to neutral connection and a "GEC" to ground rod at house.
The existing ATS was done recently 2023, but the 3 wire and ground to neutral connection was there before.
I come across several jobs where an ATS is load-side and there is a ground to neutral connection in the ATS.
I am adding a solar PV dedicated panel and tapping the feeders.
My questions are:
A) If the ground to neutral connection is allowed in the ATS then we would also need a ground to neutral connection in the solar PV dedicated panel?
B) Is a three wire load-side tap allowed? Seems like old code yes, but new code no. Apparently my AHJ is allowing this.
C) Is a load-side ground to neutral allowed in automatic transfer switches (in this example with a remote main)? I see this quite frequently on jobs.
D) Are there code considerations for a post mounted remote Meter/Main since it is not a "separate building"?

E) A solution could be to run an EGC from remote main panel to ATS then disconnect G-N in ATS. No G-N connection in PV panel, just connect PV panel EGC to the new EGC in ATS? ..what would you all do?

 

[electrofelon]

It seems the only way your 3 wire between the pedestal and the house is compliant is if you call the breaker in the meter main the "emergency disconnect, not service equipment". In that case they remain service conductors and the breaker in the ATS is your service disconnect. You can tap ahead of the breaker in the ATS but note it will be a " service tap" which would essentially fall under 230.40 exception # 2, or 5 depending on what you want to call it: a PV tap, or a general tap that happens to also serve PV.

What code cycle are you under?

 

[jaggedben]

My questions are:

A) If the ground to neutral connection is allowed in the ATS then we would also need a ground to neutral connection in the solar PV dedicated panel?

Absolutely not.

B) Is a three wire load-side tap allowed? Seems like old code yes, but new code no. Apparently my AHJ is allowing this.

The tap is not what is at issue for me here.
What's at issue is that the code nowadays requires an EGC between the meter/main at the post and the ATS at the house.
However 250.32(B) has an exception that allows you to use the neutral as the ground fault return path if the underground feeder was installed in compliance with the code at the time. (pre-2005 NEC). If this is how it will be done, then neutral-ground bonding in the ATS should absolutely stay. I'm not clear if this is what the AHJ has approved for you to do this under that exception, or if what they have said they will allow is in reference to a different issue.

C) Is a load-side ground to neutral allowed in automatic transfer switches (in this example with a remote main)? I see this quite frequently on jobs.

It has nothing in particular to do with transfer switches. (Especially not in this case where the neutral isn't switched by the ATS.) Generally, there can't be a N-G bond on the load side of the service disconnect in the same system. (The exception in 250.32(B) is the only one I know of.) If an ATS is used as a service disconnect then having the N-G bond there is correct.

D) Are there code considerations for a post mounted remote Meter/Main since it is not a "separate building"?

It is considered a separate structure. Having grounding electrodes at both the post and the house is correct.

E) A solution could be to run an EGC from remote main panel to ATS then disconnect G-N in ATS. No G-N connection in PV panel, just connect PV panel EGC to the new EGC in ATS? ..what would you all do?

This could be a solution but I would first try to get explicit approval from the AHJ for invoking the exception in 250.32(B).

 

[electrofelon]

I missed that the 3 wire was there before and thus possibly/likely allowed at the time. So, it seems that there are two ways to call the 3-wire ok and that is either that it was ok at the time of original installation (the code section JB quoted), or you could go the emergency disconnect route I mentioned. One method will make those conductors serving the house a feeder and the other will make them SEC's. I think either will work with what the OP has drawn. the feeder route will make the PV panel a "subpanel", and the SEC route will make it a service panel that has load side PV in it. Do you agree @jaggedben ?

 

[jaggedben]

If the meter/main is within sight of (less than 50ft) from the house then I think 230.85 could also work, yes. If on the 2020 or 2023 NEC.

 

[darunedefig]

It seems the only way your 3 wire between the pedestal and the house is compliant is if you call the breaker in the meter main the "emergency disconnect, not service equipment". In that case they remain service conductors and the breaker in the ATS is your service disconnect. You can tap ahead of the breaker in the ATS but note it will be a " service tap" which would essentially fall under 230.40 exception # 2, or 5 depending on what you want to call it: a PV tap, or a general tap that happens to also serve PV.

What code cycle are you under?

2017 NEC

 

[electrofelon]

2017 NEC

Ok so a feeder tap it is then. Note your EGC is too small. Also make sure you use the 10 foot tap rule as your ampacity is a hair to low to use the 25' rule.

 

[darunedefig]

This situation does seem to meet the 3 points needed for the exception found in 250.32(B).
The ATS will remain with the N-G bond even though it is load-side.
You said"

Absolutely not.

" to the N-G bond in the PV dedicated panel.
Since not on the 2020 NEC yet then 230.85 does not exist for me yet and can't use the "emergency disconnect" route that @electrofelon mentioned. (though my future self thanks you)
It sounds like if we were able to use 230.85 then the meter/main would be the "emergency disconnect" and the ATS would be the "service disconnect" (assuming within 50'/line of sight). In this case the PV panel could have the N-G bond? (and absolutely not would be a maybe/yes?)

For the 250.32(B) exception, The PV dedicated panel would have it's neutral connect to the ATS neutral.
The EGC from PV dedicated panel would connect to the ATS ground bar.
The N-G bond would not happen in the PV dedicated panel, but instead in the ATS.

Below is not for this job described in original post, but
Just FYI, NY requires that a N-G bond happen in the PV dedicated panel when we do a supply side connection inside a main service disconnect. The N-G bond happens in two places the MSP and the PV dedicated panel.

 

[electrofelon]

This situation does seem to meet the 3 points needed for the exception found in 250.32(B).
The ATS will remain with the N-G bond even though it is load-side.
You said"

" to the N-G bond in the PV dedicated panel.
Since not on the 2020 NEC yet then 230.85 does not exist for me yet and can't use the "emergency disconnect" route that @electrofelon mentioned. (though my future self thanks you)
It sounds like if we were able to use 230.85 then the meter/main would be the "emergency disconnect" and the ATS would be the "service disconnect" (assuming within 50'/line of sight). In this case the PV panel could have the N-G bond? (and absolutely not would be a maybe/yes?)

well probably. Might depend on what you call it. If it's a 230.40 exception #2 additional service disconnect panel then yes it's just like any other service panel fed with 3 wire and with a main bonding jumper. If it's a line side tap, earlier codes ( I think 2017 applies here) weren't clear on whether you Bond or run 4 wire to your PV disconnect.

For the 250.32(B) exception, The PV dedicated panel would have it's neutral connect to the ATS neutral.
The EGC from PV dedicated panel would connect to the ATS ground bar.
The N-G bond would not happen in the PV dedicated panel, but instead in the ATS.

correct

Below is not for this job described in original post, but
Just FYI, NY requires that a N-G bond happen in the PV dedicated panel when we do a supply side connection inside a main service disconnect. The N-G bond happens in two places the MSP and the PV dedicated panel.

Remember a supply side connection is essentially the same thing as just adding another "normal" service disconnect under 230.40 exception #2. If you are in NY, I have called my PV disconnects 230.40 ex #2 and #3 disconnects on my NYSERDA applications and they accept it. This is particularly useful for residential ground mounts because with ex #3 you can get around the 10-ft to the disconnect requirement and run three wire service conductors all the way to the array.

 

[jaggedben]

Yeah I was not viewing the PV panel as being in any way a service disconnect. But I suppose it's possible to go down that route and muddy the waters. Not my preference as it creates a looping parallel path for normal neutral current. But if that is what you have to do...

 

[darunedefig]

Ok so a feeder tap it is then. Note your EGC is too small. Also make sure you use the 10 foot tap rule as your ampacity is a hair to low to use the 25' rule.

Instead of upsizing the EGC, I downsized the conductors going from 40A breaker in PV panel to the feeder tap.
200 * 0.1 = 20A
which < 40A .. ok
I previously had sized for 60A because wasn't sure if I needed to apply to the PV panel
as I would for a Supply Side Connection to a Main Service Disconnect:
230.79 Rating of Service Disconnecting Means. (D) service disconnecting
means shall have a rating of not less than 60 amperes.
Now I know with the 3 feeder wire load-side tap the PV panel should never have N-G bond.

I also see if I did go with #6 wire then I would have needed to upsize the EGC for the 200A (NEC table 250.122) to #6, but
also taking into consideration 250.122(A) "in no case shall they be required to be larger than the circuit conductors supplying the equipment"
which would also be #6.

Thanks!