AC PV disconnect count towards six service disconnect rule

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hhsting

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Attached MLO main service switchboard is service entrance rated equipment 208/120V three phase 4000A. The main service switchboard is MLO and has Six main service disconnects breakers feeding loads in residential apartment complex building four floors.

In the picture there is note #29 which says to provide 800AF space provision for future PV system feedback breaker in addition to the six main service breakers.

Following questions:

1. Would the note #29 PV system backfeed breaker be counted as seventh disconnect or not based on NEC 2017?

2. As of right now its 800AF space can that count towards six main service disconnect rules?

3. Does MLO service entrance rated equipment with sections as shown in picture come with eight disconnects?

4. From the way I see it the future PV system feedback breaker would be connected In the main service disconnects Not ahead of main service disconnecting means. Correct or incorrect

a6751068628341ab6301037a6c17ae0d.jpg
 
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hhsting said:
Attached MLO main service switchboard is service entrance rated equipment 208/120V three phase 4000A. The main service switchboard is MLO and has Six main service disconnects breakers feeding loads in residential apartment complex building four floors.

In the picture there is note #29 which says to provide 800AF space provision for future PV system feedback breaker in addition to the six main service breakers.

Following questions:

1. Would the note #29 PV system backfeed breaker be counted as seventh disconnect or not based on NEC 2017?

2. As of right now its 800AF space can that count towards six main service disconnect rules?

3. Does MLO service entrance rated equipment with sections as shown in picture come with eight disconnects?

4. From the way I see it the future PV system feedback breaker would be connected In the main service disconnects Not ahead of main service disconnecting means. Correct or incorrect

a6751068628341ab6301037a6c17ae0d.jpg
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Anyone know?
 
This is controversial under the 2017 code. Mike Holt once put out an opinion that it does not count because the powerflow direction doesn't accord with the definition of a service in that cycle, therefore it is not a service disconnect. However the definition of a service changed in 2020 to take away that argument. From a common sense point of view, I see no reason it shouldn't be counted.
 
If it were in a separate panel, you would be better positioned to argue that it does not count as the seventh disconnect under the 2017 Code.
If it is in the MLO panel with all of the other six breakers, a responder wanting to disconnect buillding power at the service panel would have no way of instantly knowing that it did not need to be opened, On that basis (logically and therefore anathema to the Code) I would count it as number seven even under 2017.
 
jaggedben said:
This is controversial under the 2017 code. Mike Holt once put out an opinion that it does not count because the powerflow direction doesn't accord with the definition of a service in that cycle, therefore it is not a service disconnect. However the definition of a service changed in 2020 to take away that argument. From a common sense point of view, I see no reason it shouldn't be counted.
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I dont have NEC 2017 on me but connection ahead of service disconnecting means is allowed But would you say the connection in post #1 is made in service disconnecting means Not ahead?
 
Another thing is Service entrance rated equipment that is MLO would it come with the seventh breaker specifically for solar? Anyone know manufacturer allow this?
 
GoldDigger said:
If it were in a separate panel, you would be better positioned to argue that it does not count as the seventh disconnect under the 2017 Code.
If it is in the MLO panel with all of the other six breakers, a responder wanting to disconnect buillding power at the service panel would have no way of instantly knowing that it did not need to be opened, On that basis (logically and therefore anathema to the Code) I would count it as number seven even under 2017.
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If you can provide me with code section as plan reviewer i cannot any argument if its not on design basis
 
hhsting said:
I dont have NEC 2017 on me but connection ahead of service disconnecting means is allowed But would you say the connection in post #1 is made in service disconnecting means Not ahead?
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Any disconnect connected to a MLO bus is on the line side of the service disconnecting means. This is not a physical condition, it is an electrical condition. Any connecting that is not supplied by a service disconnect is ahead of the service disconnecting means.
 
GoldDigger said:
If it were in a separate panel, you would be better positioned to argue that it does not count as the seventh disconnect under the 2017 Code.
If it is in the MLO panel with all of the other six breakers, a responder wanting to disconnect buillding power at the service panel would have no way of instantly knowing that it did not need to be opened, On that basis (logically and therefore anathema to the Code) I would count it as number seven even under 2017.
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The emergency responder would need to open it to disconnect building power.
 
don_resqcapt19 said:
Any disconnect connected to a MLO bus is on the line side of the service disconnecting means. This is not a physical condition, it is an electrical condition. Any connecting that is not supplied by a service disconnect is ahead of the service disconnecting means.
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If you approach it that way I would sure want some engineering due to that service section being labeled as 1200 amps and the proposed PV breaker is 800 amps (could not make out the size of the other breakers). Code may address it but I can't see it in Art 705 as far as line size buss.
 
augie47 said:
If you approach it that way I would sure want some engineering due to that service section being labeled as 1200 amps and the proposed PV breaker is 800 amps (could not make out the size of the other breakers). Code may address it but I can't see it in Art 705 as far as line size buss.
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How is it not a line side connection? Line side is everything on the line side of the service disconnect(s). I see the bus as being covered by the service entrance conductors and the overcurrent protection of the bus of a MLO panel would be per 230.90(A), Exception #3.
 
augie47 said:
I wouild mark the drawing "Violation of 230.72" and let the designer fight the battle.
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Ofcourse the engineer can come back saying he has grouped six disconnects associated with set of service entrance conductors for 230.40 exception no. 2 and for different set of service entrance for 230.40 exception no. 5 which is solar their is nothing to group. Engineer can say he met 230.72 not sure whats wrong


Then what i can say not exactly he hasnt complied with 230.71 since the engineer has also grouped disconnects associated with service entrance conductors of 230.40 exception no.2 and exception no. 5 while 230.71? Is that what your thinking?
 
It certainly isn't a load side connection so that would make it "line side". My concern, and the reason I would want engineering documentation, would be the fact that it appears that Section of the gear is rated 1200 amps, perhaps less than the PV 800 amps & other breakers in the Section.
705.12 goes to great length to assure load side bussing isn't overloaded unfortunately they don't seem to do so for line buss.
 
hhsting said:
Ofcourse the engineer can come back saying he has grouped six disconnects associated with set of service entrance conductors for 230.40 exception no. 2 and for different set of service entrance for 230.40 exception no. 5 which is solar their is nothing to group. Engineer can say he met 230.72 not sure whats wrong


Then what i can say not exactly he hasnt complied with 230.71 since the engineer has also grouped disconnects associated with service entrance conductors of 230.40 exception no.2 and exception no. 5 while 230.71? Is that what your thinking?
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don't post #9 I think negates my concern about 230.72.,,, my other concern remains but I will leave it to sharper minds to decide,.
 
augie47 said:
If you approach it that way I would sure want some engineering due to that service section being labeled as 1200 amps and the proposed PV breaker is 800 amps (could not make out the size of the other breakers). Code may address it but I can't see it in Art 705 as far as line size buss.
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The other two breakers are 600A
 
augie47 said:
don't post #9 I think negates my concern about 230.72.,,, my other concern remains but I will leave it to sharper minds to decide,.
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I see but also this is brand new service entrance rated MLO gear. Do manufacturer of the gear with MLO provide more than 6 breakers?
 
In the MLO service switchboard post #1 picture:

First 4000A section has 2x1200A breaker going to building load

Second 4000A section has 2x1200A breaker going to building load

1200A section has 2x600A breakers going to building load


Based on 700.12(A) the total overcurrent is 5000A and thats Without counting the solar breaker. The rating of service is 4000A. The sum of all overcurrent protection size exceeds utility rating which is 4000A. I dont see how engineer can even put 800A space and any solar breakers on line side of the switchboard. Am I correct or incorrect?
 
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augie47 said:
It certainly isn't a load side connection so that would make it "line side". My concern, and the reason I would want engineering documentation, would be the fact that it appears that Section of the gear is rated 1200 amps, perhaps less than the PV 800 amps & other breakers in the Section.
705.12 goes to great length to assure load side bussing isn't overloaded unfortunately they don't seem to do so for line buss.
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The PV isn't a load. Max amps the busbar can see is the sum of the load breakers regardless of whether the PV is there or not. This is why 705 has nothing to say about it, it's considered not to matter.
 
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