supply side PV connection

Smart $

Esteemed Member
Location
Ohio
what about electric power production source conductors per 705.31
That is a valid possibility... but it seems in adding that section to the 2014 NEC, the proponents forgot to specifically note it as an amendment to 230.40.

Also, doesn't a connection to the load end of service-entrance conductors qualify as a connection to the service?

I'd swear most all the proposals to Code either want to coin new terms or someone wants to practice their legalese... and they completely forget about the simple matters they are attempting to support. For example, 705.31 requires OCPD within 10 feet of supply side connection to a service... but where does 705 specify a disconnecting means between the connection and the OCPD?
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
Look, if you want to give me an argument that 250.24(C) ought to be stricken from the code because there's no safety justification for it, I'm happy to listen to that argument. I do not know why that rule was put in and whether it is truly justified and important. But I begin from the assumption that all of these code sections are in there because there was a legitimate safety reason for them. I would need to be presented with an argument concerning each such rule before I accept that it doesn't undermine safety to ignore them.
So, anything that deviates from your interpretation of the code is inherently unsafe? We are just going to have to agree to disagree on that one. Just because one interpretation of the code describes a way to do something that is safe, that doesn't mean that it is the only way to do it safely and compliant to a different interpretation of the NEC. The alternate interpretation that most of the AHJ's in Texas use is just as safe, IMO, and utility engineers whom I know and respect stand by their interpretation.

If you were building supply side interconnected PV systems in Texas, I am afraid you would find it a frustrating experience, at least in Austin. It would not matter whether you accept it or not; the argument you would be presented with is that you must design and build your systems the AHJ's way or fail your inspection.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
So, anything that deviates from your interpretation of the code is inherently unsafe? We are just going to have to agree to disagree on that one. Just because one interpretation of the code describes a way to do something that is safe, that doesn't mean that it is the only way to do it safely and compliant to a different interpretation of the NEC. The alternate interpretation that most of the AHJ's in Texas use is just as safe, IMO, and utility engineers whom I know and respect stand by their interpretation.

If you were building supply side interconnected PV systems in Texas, I am afraid you would find it a frustrating experience, at least in Austin. It would not matter whether you accept it or not; the argument you would be presented with is that you must design and build your systems the AHJ's way or fail your inspection.
Look, I don't mean to be harsh, and rereading my response to you it does sound harsh to me, so I apologize for that. At the end of the day it really doesn't matter what you or I think. I design and build to the AHJ's specifications because I don't have a choice, and I do not challenge this particular interpretation (I do challenge some and I have won a few) because the code itself is not clear and unambiguous. Maybe the code writers will fix this in 2017 and we will all build these systems the same way forever thereafter.

I can dream, can't I? :D
 

jaggedben

Senior Member
ggunn, I appreciate your last response.

My comments in this thread are really entirely with a mind to what the code ought to say to improve the situation and reduce confusion for everyone. With respect to safety, it just seems to me that declaring these conductors service conductors would be the most conservative call with regards to safety. It might not be much less safe to determine otherwise, and I'm open to hearing arguments, but that's how I see it right now.

When it comes working with AHJs, or giving advice to others doing so, my approach is pretty much exactly what yours is, and I'm sure that if I were working in Texas I would have come to it even sooner than I have in California. :happyyes:
 

Solar Harris

Member
Location
NYC
(NEW HERE) Supply Side PV Connection-Inspectors Don't Want Neutral Bonded?

(NEW HERE) Supply Side PV Connection-Inspectors Don't Want Neutral Bonded?

Hey gang,

I'm new here so bare with me if I posted this in the incorrect spot. I've read through alot of this post but someone might've answered this already. I recently had an inspector who told me a new rule for NYC (where I install solar):

We typically install supply side connections. He told me that since my disconnect is not a service disconnect, I shouldn't have bonded the neutral. I know 705.12 permits connecting to the supply side but the equipment is not described as a "service disconnect" as in 230. We always earthed that disconnect by bonding the neutral and adding a supplementary gec as required in 690.47.

I was told that the minimum I could use for my tap conductors was #4 and my disconnect has to be rated at a minimum of 100a. I asked for a reference but was told it was in the NEC. I thought 230.21 gave permission to rate the conductors at 10% of the services ocpd. Our job was a 52A solar system. We used #6 to tap, 60a service rated disconnect with 55a fuses.

We connect our solar to the supply side. So is it not considered a service disconnect? And if the tap rules apply to those conductors is there a minimum of #4 and where would that be? My Polaris taps show #10-1/0 rating so I have no idea where this rule comes from. And do you think he is on the right side of the neutral bonding debate?

Thanks anyone who comments.
 

jaggedben

Senior Member
Hey gang,

I'm new here so bare with me if I posted this in the incorrect spot. I've read through alot of this post but someone might've answered this already. I recently had an inspector who told me a new rule for NYC (where I install solar):

We typically install supply side connections. He told me that since my disconnect is not a service disconnect, I shouldn't have bonded the neutral. I know 705.12 permits connecting to the supply side but the equipment is not described as a "service disconnect" as in 230. We always earthed that disconnect by bonding the neutral and adding a supplementary gec as required in 690.47.

I was told that the minimum I could use for my tap conductors was #4 and my disconnect has to be rated at a minimum of 100a. I asked for a reference but was told it was in the NEC. I thought 230.21 gave permission to rate the conductors at 10% of the services ocpd. Our job was a 52A solar system. We used #6 to tap, 60a service rated disconnect with 55a fuses.

We connect our solar to the supply side. So is it not considered a service disconnect? And if the tap rules apply to those conductors is there a minimum of #4 and where would that be? My Polaris taps show #10-1/0 rating so I have no idea where this rule comes from. And do you think he is on the right side of the neutral bonding debate?

Thanks anyone who comments.
Whether it is a service disconnect is what is up for debate. So if he says it's not a service disconnect according to the code, well, fine, that's not an unreasonable interpretation. However, once he makes that decision he ought to be consistent in his reasoning. For example, stop enforcing any requirements of article 230.

As for the ratings of conductors and switches, did he tell you his reasoning? Because if it's related to the minimum requirements for services then he's totally off base. But if he just thinks that's what's required for your solar output, he could be making sense. If your inverter output is 52A then your output needs to be rated 65A for continuous use. However if your 52A already includes the 125% factor for continuous use, then he's just wrong. He shouldn't be looking at any sizing requirements except 705.60, in my opinion, and 60A would be fine. For that matter, a 60A service disconnect is fine, too. See 230.79(A) or (D).

As far as bonding the neutral, one could make an argument that your disconnect is still 'at the service' per 250.92, even if it's not a service disconnect itself. But if he doesn't agree and cites objectionable current, fine, remove the green screw. I always run both a neutral and ground in these situations (on small systems), and install the screw. If the inspector asks why, I say it's a service disconnect and my ground is a GEC. If the inspector doesn't agree, I remove the screw and say my ground now an EGC. The ground has to terminate at another service disconnect enclosure for this to work. On bigger systems you probably want to know the answer before you install.

When you said 230.21 you must mean 240.21(B). The problem with using that section is that the OCPD is typically the one on the supply side of the tap. When you say the service OCPD you're referring to one on the load side of your tap. It makes no sense to use this rule (which is one reason I think the NFPA should not be telling people it's a feeder.) I don't know what more to say about that, except that again, the only sizing requirements that definitely apply are in 705.60.

Bottom line, the code is not clear, and it usually costs more to argue with the AHJ after you've installed a system than to either find out what they think beforehand, or install with options.
 
Last edited:

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
Hey gang,

I'm new here so bare with me if I posted this in the incorrect spot. I've read through alot of this post but someone might've answered this already. I recently had an inspector who told me a new rule for NYC (where I install solar):

We typically install supply side connections. He told me that since my disconnect is not a service disconnect, I shouldn't have bonded the neutral. I know 705.12 permits connecting to the supply side but the equipment is not described as a "service disconnect" as in 230. We always earthed that disconnect by bonding the neutral and adding a supplementary gec as required in 690.47.

I was told that the minimum I could use for my tap conductors was #4 and my disconnect has to be rated at a minimum of 100a. I asked for a reference but was told it was in the NEC. I thought 230.21 gave permission to rate the conductors at 10% of the services ocpd. Our job was a 52A solar system. We used #6 to tap, 60a service rated disconnect with 55a fuses.

We connect our solar to the supply side. So is it not considered a service disconnect? And if the tap rules apply to those conductors is there a minimum of #4 and where would that be? My Polaris taps show #10-1/0 rating so I have no idea where this rule comes from. And do you think he is on the right side of the neutral bonding debate?

Thanks anyone who comments.
If you have been reading this thread and/or the others like it, you can see that this is a much debated and occasionally highly contentious issue. If you are looking for concise unambiguous language in the code to use to prove the inspector wrong, you are out of luck, I'm afraid, and that would be true whichever stance the inspector takes. Your best bet is to have a preconstruction meeting with the AHJ to find out which way they swing on this issue and do it their way.
 

Smart $

Esteemed Member
Location
Ohio
.... He told me that since my disconnect is not a service disconnect, I shouldn't have bonded the neutral. I know 705.12 permits connecting to the supply side but the equipment is not described as a "service disconnect" as in 230. We always earthed that disconnect by bonding the neutral and adding a supplementary gec as required in 690.47.
...
Welcome! :thumbsup:


Regardless of whether the disconnect is a service disconnect or not, as a matter of fact in this particular case you are permitted to bond the grounded conductor to the equipment grounding terminal/bus and enclosure. See 250.142. Note it does not provide any specifics for sizing, so I'd base it on 250.102.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
Welcome! :thumbsup:


Regardless of whether the disconnect is a service disconnect or not, as a matter of fact in this particular case you are permitted to bond the grounded conductor to the equipment grounding terminal/bus and enclosure. See 250.142. Note it does not provide any specifics for sizing, so I'd base it on 250.102.
If you do that in Austin I am pretty sure the inspector will make you separate them.
 

jaggedben

Senior Member
Smart$, thanks for pointing out that reference. I had been unaware of or had forgotten it.

It raises an interesting question though: If the PV disconnect is on the supply side of the service disconnecting means, but the disconnect is not a service disconnect, then is the entire PV system on the supply side? Could I bond the entire PV system to the grounded conductor (or at least as far as the inverter?) And don't bring up objectionable current for inverters that only use the neutral for sensing voltage! :D

Yes, I'm being a bit facetious. Really, it's just another reason for me to think that the best way to clarify the whole question would be to declare the PV disconnect a service disconnecting means.
 

Smart $

Esteemed Member
Location
Ohio
If you do that in Austin I am pretty sure the inspector will make you separate them.
It's like when the doctor touches a sore spot and asks if it hurts. You say yes, then he says, "Then don't do that!" That said, and continuing the analogy in a manner of speaking, the doctor is not required to touch the sore spot... but it'll still be sore.

:D
 

Smart $

Esteemed Member
Location
Ohio
Smart$, thanks for pointing out that reference. I had been unaware of or had forgotten it.

It raises an interesting question though: If the PV disconnect is on the supply side of the service disconnecting means, but the disconnect is not a service disconnect, then is the entire PV system on the supply side? Could I bond the entire PV system to the grounded conductor (or at least as far as the inverter?) And don't bring up objectionable current for inverters that only use the neutral for sensing voltage! :D

Yes, I'm being a bit facetious. Really, it's just another reason for me to think that the best way to clarify the whole question would be to declare the PV disconnect a service disconnecting means.
Facetiousness aside, yes, the entire PV system can be considered on the supply side of the service disconnecting means. And I believe the combo EGC/GEC of 690.47(C)(3) does exactly what you are asking.
 

Solar Harris

Member
Location
NYC
Whether it is a service disconnect is what is up for debate. So if he says it's not a service disconnect according to the code, well, fine, that's not an unreasonable interpretation. However, once he makes that decision he ought to be consistent in his reasoning. For example, stop enforcing any requirements of article 230.

As for the ratings of conductors and switches, did he tell you his reasoning? Because if it's related to the minimum requirements for services then he's totally off base. But if he just thinks that's what's required for your solar output, he could be making sense. If your inverter output is 52A then your output needs to be rated 65A for continuous use. However if your 52A already includes the 125% factor for continuous use, then he's just wrong. He shouldn't be looking at any sizing requirements except 705.60, in my opinion, and 60A would be fine. For that matter, a 60A service disconnect is fine, too. See 230.79(A) or (D).

As far as bonding the neutral, one could make an argument that your disconnect is still 'at the service' per 250.92, even if it's not a service disconnect itself. But if he doesn't agree and cites objectionable current, fine, remove the green screw. I always run both a neutral and ground in these situations (on small systems), and install the screw. If the inspector asks why, I say it's a service disconnect and my ground is a GEC. If the inspector doesn't agree, I remove the screw and say my ground now an EGC. The ground has to terminate at another service disconnect enclosure for this to work. On bigger systems you probably want to know the answer before you install.

When you said 230.21 you must mean 240.21(B). The problem with using that section is that the OCPD is typically the one on the supply side of the tap. When you say the service OCPD you're referring to one on the load side of your tap. It makes no sense to use this rule (which is one reason I think the NFPA should not be telling people it's a feeder.) I don't know what more to say about that, except that again, the only sizing requirements that definitely apply are in 705.60.

Bottom line, the code is not clear, and it usually costs more to argue with the AHJ after you've installed a system than to either find out what they think beforehand, or install with options.

Excellent! This was my position with our licensee and our engineers who are all now scratching their heads. Our company engineers these systems and sets a list of requirements for the electricians to follow (obviously based on municipality and local codes). In every state we work in there are minor changes-like the ground rod argument and now this!

So if we are going to say that connecting to the supply side with a disconnecting means does not count as a service switch what about the special conditions in 230 2 (A) 1-6? So are AHJs going to start saying well fire pumps are acceptable because of the actual word "fire pump" but pv is not because it's not actually listed? Most AHJs I deal with would agree that PV falls under these special conditions and therefore by attaching via supply side tap now creates a service switch which requires to be earthed.

Hey thanks everyone who commented!
 

Smart $

Esteemed Member
Location
Ohio
...
So if we are going to say that connecting to the supply side with a disconnecting means does not count as a service switch what about the special conditions in 230 2 (A) 1-6? So are AHJs going to start saying well fire pumps are acceptable because of the actual word "fire pump" but pv is not because it's not actually listed? Most AHJs I deal with would agree that PV falls under these special conditions and therefore by attaching via supply side tap now creates a service switch which requires to be earthed.
It appears you do not completely understand what a [single] service is. In short, it is one drop or one lateral, and the special case of 230.40 Exception No. 2. From there you are generally only permitted one set of service-entrance conductors. That is the basic single service.

However, there are several exceptions which permit two or more service-entrance conductors... and each of those is permitted up to 6 grouped service disconnecting means (but the groups cannot be in the same location). This is still a single service. Connecting a PV system to the supply side of a service does not create an additional service. 230.2 does not apply.
 

jaggedben

Senior Member
230.2 is one of those sections that implies that the PV connection is, or at least can be, a service. But it only applies if you want a separate connection to the utility with a separate service point. (One problem with this in the real world is that the utility would want a separate meter and then net-energy-metering would not be possible.)
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
230.2 is one of those sections that implies that the PV connection is, or at least can be, a service. But it only applies if you want a separate connection to the utility with a separate service point. (One problem with this in the real world is that the utility would want a separate meter and then net-energy-metering would not be possible.)
Why not? It's simple math to subtract the reading on one meter from the reading on the other. For example, that's how community solar works; the two meters are not even in the same location.
 

Smart $

Esteemed Member
Location
Ohio
Why not? It's simple math to subtract the reading on one meter from the reading on the other. For example, that's how community solar works; the two meters are not even in the same location.
I believe with most POCO's where two or more meters are on one account, each meter is itemized separately. With net metering, it is just one meter, one reading value. But you are correct in that the net balance for multiple meters is calculated.
 
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