NEC 2023: 705.11 "Source Connections to a Service"

[pkhosravani]

Comparing NEC 2020: 705.11 to NEC 2023: 705.11, there looks to be some important changes - possibly helpful changes - for the PV industry. With that said, I'm not an expert and because NEC 2023 was just released, I've been unsuccessful in finding clarification thus far, so I'm putting it to the members of this forum to help a novice, like myself, understand the changes and their implications for interconnecting PV to the supply side.

In particular, NEC 2020: 705.11 (c) (1) through (c) (2) are totally gone, missing, disappeared from the NEC 2023 code.

The NEC 2020: 705.11 (c) (1) required an overcurrent device be located within 3m (10 ft) of conductor length in dwelling units and 5m (16.5 ft) in other than dwelling units from the point of connection to the service. Followed by section (c) (2) that allows for current limiters on all ungrounded conductors if the overcurrent device is located within 20m (71 ft) of conductor length from the point of connection to the service, etc, etc.

With both (1) and (2) gone from the code, it looks to me that we when making a supply-side connection of electric power production sources (aka PV) we can now have an infinite length of conductor between the our supply-side connection point (usually an IPC or a insulated multi-tap connector commonly referred to as a Polaris block) to the nearest OCPD, which is usually the PV-Utility AC disconnect switch located outdoor & fused. Is that correct? Did I miss anything? Am I way off base?

 

[ggunn]

Comparing NEC 2020: 705.11 to NEC 2023: 705.11, there looks to be some important changes - possibly helpful changes - for the PV industry. With that said, I'm not an expert and because NEC 2023 was just released, I've been unsuccessful in finding clarification thus far, so I'm putting it to the members of this forum to help a novice, like myself, understand the changes and their implications for interconnecting PV to the supply side.

In particular, NEC 2020: 705.11 (c) (1) through (c) (2) are totally gone, missing, disappeared from the NEC 2023 code.

The NEC 2020: 705.11 (c) (1) required an overcurrent device be located within 3m (10 ft) of conductor length in dwelling units and 5m (16.5 ft) in other than dwelling units from the point of connection to the service. Followed by section (c) (2) that allows for current limiters on all ungrounded conductors if the overcurrent device is located within 20m (71 ft) of conductor length from the point of connection to the service, etc, etc.

With both (1) and (2) gone from the code, it looks to me that we when making a supply-side connection of electric power production sources (aka PV) we can now have an infinite length of conductor between the our supply-side connection point (usually an IPC or a insulated multi-tap connector commonly referred to as a Polaris block) to the nearest OCPD, which is usually the PV-Utility AC disconnect switch located outdoor & fused. Is that correct? Did I miss anything? Am I way off base?

I have not yet seen a 2023 NEC, but that would be an interesting development. We frequently see commercial MDPs in electrical rooms in the middle of buildings with service conductors run all the way to them; why should PV conductors be any different?

 

[don_resqcapt19]

Those are now very clearly service conductors and must comply with Parts VI, and VII of Article 230.
If the line side tap is outside, you would have an unlimited length. If it is inside the disconnect/OCPD would have to be at the point of the tap.

 

[don_resqcapt19]

I have not yet seen a 2023 NEC, but that would be an interesting development. We frequently see commercial MDPs in electrical rooms in the middle of buildings with service conductors run all the way to them; why should PV conductors be any different?

If those conductors are actually inside the building, that is a code violation as the service disconnect would not be nearest the point of entrance of the service conductors. 230.6 gives conditions that would permit those service conductors to be run to the service equipment in the middle of a building

 

[jaggedben]

Those are now very clearly service conductors and must comply with Parts VI, and VII of Article 230.
...

How does 2023 now make this clear? I don't have my copy yet.

 

[pkhosravani]

Those are now very clearly service conductors and must comply with Parts VI, and VII of Article 230.
If the line side tap is outside, you would have an unlimited length. If it is inside the disconnect/OCPD would have to be at the point of the tap.

I'm not following, could you dumb it down to a layman's level.

Let's say we have a commercial property, and the main service disconnect is the actual main breaker in the MDP. We have PV on the roof and we run our conduit down over the side of the building to the inverter then to our PV-Utility AC disconnect switch.The PV system exceeds the busbar rating of the MB MDP, so we have to perform a supply side connection using IPC. We punch out of our external disconnect and into the electrical room, the PV point of interconnection is inside the MDP which is inside the building. The PV POI is below the Main Breaker, which is 100' of conductor length away from our last OCPD which is outside the building...is that code compliant according to the 2023 NEC?

If not, please help me understand how to make it code compliant. Thank you in advance!

 

[ggunn]

Those are now very clearly service conductors and must comply with Parts VI, and VII of Article 230.
If the line side tap is outside, you would have an unlimited length. If it is inside the disconnect/OCPD would have to be at the point of the tap.

That is the way it is in the 2020 NEC, where "at the point of the tap" means within 16.5 feet in a non dwelling building per 705.11. Apparently the language specifying the maximum conductor length has been removed or moved.

For the moment the point is moot, though; it will be a while yet before we see AHJ's starting to adopt the 2023 NEC.

 

[wwhitney]

How does 2023 now make this clear? I don't have my copy yet.

You can read it online at nfpa.org/70 with a free account. Basically 705.11 repeatedly refers to the conductors for the line side connection as service conductors.

Cheers, Wayne

 

[jaggedben]

I'm not following, could you dumb it down to a layman's level.

Read article 230 and familiarize yourself with the rules for service conductors and service disconnects. IMO the way it always should have been, more or less.

... We punch out of our external disconnect and into the electrical room, the PV point of interconnection is inside the MDP which is inside the building. The PV POI is below the Main Breaker, which is 100' of conductor length away from our last OCPD which is outside the building...is that code compliant according to the 2023 NEC? ...

The total distance doesn't matter, but the conductors may not be run inside the building for any meaningful distance. Depending on how your AHJ interprets 'nearest the entrance' to the building. If you put an additional disconnect inside. directly next to the MDP inside, you're probably okay. If you can 'punch out' of the MDP directly outside, you're probably okay to continue outside as far as you like to your outside disconnect, so long as it all stays outside.

 

[don_resqcapt19]

I'm not following, could you dumb it down to a layman's level.

Let's say we have a commercial property, and the main service disconnect is the actual main breaker in the MDP. We have PV on the roof and we run our conduit down over the side of the building to the inverter then to our PV-Utility AC disconnect switch.The PV system exceeds the busbar rating of the MB MDP, so we have to perform a supply side connection using IPC. We punch out of our external disconnect and into the electrical room, the PV point of interconnection is inside the MDP which is inside the building. The PV POI is below the Main Breaker, which is 100' of conductor length away from our last OCPD which is outside the building...is that code compliant according to the 2023 NEC?

If not, please help me understand how to make it code compliant. Thank you in advance!

It is my opinion that if your line side connection is at the service disconnect inside the building, you need a service disconnect for the PV conductors at that point.

 

[don_resqcapt19]

How does 2023 now make this clear? I don't have my copy yet.

There was a lot of fighting going on between CMP 4 and CMP 10 to the point that CMP 10 accepted Public Input to create a new Article 231 to handle the line side conductors which are in fact service conductors. The Correlating Committee stepped in and forced the two panels to come to agreement on this issue. The result is that any conductors connected on the line side of the service disconnect are service conductors and must be installed in accordance with the rules in Article 230 for service conductors. The same with the PV system disconnect...it is a service disconnect and must be installed in accordance with Article 230. The rules I referenced in Parts VI and VII of Article 230 are the disconnect rules. 705.11(E) & (F) sends you to the Article 230 rules. 705.11(B)(2) specifically calls these conductors service conductors.

 

[ggunn]

There was a lot of fighting going on between CMP 4 and CMP 10 to the point that CMP 10 accepted Public Input to create a new Article 231 to handle the line side conductors which are in fact service conductors. The Correlating Committee stepped in and forced the two panels to come to agreement on this issue. The result is that any conductors connected on the line side of the service disconnect are service conductors and must be installed in accordance with the rules in Article 230 for service conductors. The same with the PV system disconnect...it is a service disconnect and must be installed in accordance with Article 230. The rules I referenced in Parts VI and VII of Article 230 are the disconnect rules. 705.11(E) & (F) sends you to the Article 230 rules. 705.11(B)(2) specifically calls these conductors service conductors.

OK, but going back to the original question, under the 2023 NEC how long can the conductors be from a supply side POI to the OCPD in an inside non dwelling situation without cable limiters? 705.31 used to say 10 feet and then 705.11 said 16.5 feet.

 

[wwhitney]

OK, but going back to the original question, under the 2023 NEC how long can the conductors be from a supply side POI to the OCPD in an inside non dwelling situation without cable limiters? 705.31 used to say 10 feet and then 705.11 said 16.5 feet.

The logical result from what Don described (I didn't trace through all the references) is that it would need to be immediately adjacent. As the inside service disconnect would need to be "nearest the point of entry" of the service conductors, and the same language would apply to the PV service disconnect.

Cheers, Wayne

 

[jaggedben]

OK, but going back to the original question, under the 2023 NEC how long can the conductors be from a supply side POI to the OCPD in an inside non dwelling situation without cable limiters? 705.31 used to say 10 feet and then 705.11 said 16.5 feet.

If it's all inside, they can't be any meaningful length. Disconnect directly next to the POI. Unless the AHJ has a liberal interpretation of 'nearest.'

Typing at the same time as Wayne.

 

[ggunn]

If it's all inside, they can't be any meaningful length. Disconnect directly next to the POI. Unless the AHJ has a liberal interpretation of 'nearest.'

If that is the correct interpretation, then supply side connections inside some electrical rooms could be problematic. It's weird that the rules would first get more permissive (10 feet to 16.5 feet) and then less. Stranger things have happened with the NEC, I guess.

 

[shortcircuit2]

Article 231 never made it in the Code. So the 2020 NEC 10ft, 16.5ft and 71 ft permissive rules in 705.11(C)(1) & (2) are gone for the 2023 NEC.

New 2023 section 705.11(D) says to follow part VI thru VII of article 230 where "nearest the poit of entrance" language is.

I agree with Don's interpretation that the "taps" inside the building ahead of the normal main breaker will be subject the AHJ allowance , if at all. Any supply-side connection to the service entrance conductors in that panel ahead of the main that "extends" those service entrance conductors, would be beyond what is already been permitted with the existing installation.

Make your taps outside after the meter in a (12x12 PVC jbox for example) and before entering the building, then put the disconnect outside or "nearest the point of entrance" inside. This is residential. Commercial will be a bit more difficult.

 

[electrofelon]

There was a lot of fighting going on between CMP 4 and CMP 10 to the point that CMP 10 accepted Public Input to create a new Article 231 to handle the line side conductors which are in fact service conductors. The Correlating Committee stepped in and forced the two panels to come to agreement on this issue. The result is that any conductors connected on the line side of the service disconnect are service conductors and must be installed in accordance with the rules in Article 230 for service conductors. The same with the PV system disconnect...it is a service disconnect and must be installed in accordance with Article 230. The rules I referenced in Parts VI and VII of Article 230 are the disconnect rules. 705.11(E) & (F) sends you to the Article 230 rules. 705.11(B)(2) specifically calls these conductors service conductors.

Sounds like they are moving a bit toward what I have been saying for years: get rid of this ambiguous "supply side of the normal service disconnect" nonsense and just let the 230.40 exceptions cover it (usually #2). Although sounds like they are still making it way too complicated

 

[don_resqcapt19]

If that is the correct interpretation, then supply side connections inside some electrical rooms could be problematic. It's weird that the rules would first get more permissive (10 feet to 16.5 feet) and then less. Stranger things have happened with the NEC, I guess.

Not really...it seems that a lot of the panel members on 4 don't understand the dangers of service conductors. That is what triggered the fight between the two code making panels. No matter what the function of conductors connected on the line side of the service equipment may be, they have the same hazards as any other service conductors and need to be treated as such. That is really the change for the 2023 code.

 

[ggunn]

Make your taps outside after the meter in a (12x12 PVC jbox for example) and before entering the building, then put the disconnect outside or "nearest the point of entrance" inside. This is residential. Commercial will be a bit more difficult.

I'll say. Many times the meter CTs are on the secondary lugs on the transformer; the service conductors dive underground inside the transformer enclosure and come up in the MDP. Come to think of it, would those conductors still considered to be outside the building until they come up through the slab? That would explain why the electrical room and the MSD could be in the middle of a building

 

[Tulsa Electrician]

I'll say. Many times the meter CTs are on the secondary lugs on the transformer; the service conductors dive underground inside the transformer enclosure and come up in the MDP. Come to think of it, would those conductors still considered to be outside the building until they come up through the slab? That would explain why the electrical room and the MSD could be in the middle of a building

230.6