CT Cabinet Interconnection

If a PV system pushes energy onto unprotected conductors ahead of the first OCPD, even if there are several of them, it is a supply side interconnection; I don't care what you call it.
Its not whether there are one or several service disconnect/OCPD's, my point is that the PV is/can be ONE OF THEM. Sorry if it seems like I am being argumentative, I just want to be clear that you understand my position. It seems like you do not acknowledge any ambiguity between a supply side connection and a "normal" 230.40 exception #2 install. Take a look at the attachment. Let me list some options for what the question mark is and you tell me if you think it is a supply side connection or a service with two (or more) service disconnects per 230.40 exception #2:

1. A main breaker panelboard containing only one or several breakers serving inverters.
2. A main breaker panelboard containing several breakers serving inverters and a breaker serving a light and a receptacle for a blender (milkshakes)
2. A fused disconnect switch, serving a MLO PV combiner panel with several inverter breakers.
3. A fused disconnect switch, serving a MLO panel with several inverter breakers and a breaker for a light and a receptacle for a blender (milkshakes)
4. A MLO service rated panelboard with two breakers serving inverters and a breaker for a light and a receptacle for a blender (milkshakes)
5. A MLO service rated panelboard with only two breakers serving inverters (no milkshakes :( )
 

Attachments

While I acknowledge that you're being perfectly logical and knowledgeable, I don't trust AHJs to be the same, and that's why I'd oppose your proposal. :cool: These days in my area most AHJ's are probably more familiar with 705.12(A) than with 230.40. (Yes, believe it.) Moreover one major AHJ actually has modified their local code to prohibit multiple service disconnects. So notwithstanding you're being technically correct, eliminating 705.12(A) or pairing it down would be in effect outlawing the method as ggunn states it. At the very least it could only work if replaced with a long informational note explaining why eliminating the section does not mean it was eliminated. :p
Fair enough. It is strange they came up with the whole supply side thing to begin with. Its almost like they went out of their way to make it convoluted - like thats never happened in the code before lol.
 

jaggedben

Senior Member
I vote for milkshakes.(y)

I agree with ggunn in one respect, which is that as far as overcurrent protection and the non-applicability of the load side interconnection rules they are all supply side connections. So I think it's right that 705 say something about that regardless. This semantic argument over whether it is a service disconnect or not affects only the details I mentioned above.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
I vote for milkshakes.(y)

I agree with ggunn in one respect, which is that as far as overcurrent protection and the non-applicability of the load side interconnection rules they are all supply side connections. So I think it's right that 705 say something about that regardless. This semantic argument over whether it is a service disconnect or not affects only the details I mentioned above.
I agree. All I am concerned about is how large a PV system I can connect load side vs. line side of the service OCPD. Whether it has to be treated as a separate service or not as things stand now is up to the AHJ; some say yes, others say no. I know how to design it in either case; I ask them and do what they say. Most likely I misunderstood what you were saying; if you are proposing outlawing any PV interconnection on the line side, I am strongly against it, but if all you are saying is to treat it like a service, I don't much care, at least for commercial applications. For residential systems, however, I prefer the status quo; dropping in a couple of IPC's in the MDP ahead of the main breaker is easy peasy.
 
I vote for milkshakes.(y)

I agree with ggunn in one respect, which is that as far as overcurrent protection and the non-applicability of the load side interconnection rules they are all supply side connections. So I think it's right that 705 say something about that regardless. This semantic argument over whether it is a service disconnect or not affects only the details I mentioned above.
I agree. All I am concerned about is how large a PV system I can connect load side vs. line side of the service OCPD. Whether it has to be treated as a separate service or not as things stand now is up to the AHJ; some say yes, others say no. I know how to design it in either case; I ask them and do what they say. Most likely I misunderstood what you were saying; if you are proposing outlawing any PV interconnection on the line side, I am strongly against it, but if all you are saying is to treat it like a service, I don't much care, at least for commercial applications. For residential systems, however, I prefer the status quo; dropping in a couple of IPC's in the MDP ahead of the main breaker is easy peasy.
Yes I am proposing "outlawing" line side connections, but again its just semantics. I still seem to not be getting my point accross. I am open to the possibility that I am overlooking something and if so I would like to know what it is. Take a look at the drawing and #2 from my list. You both think that is a line side PV connection? I see that definitely as 230.40 exception #2 with a load side Pv connection. It seems like you guys are saying WHENEVER you have multiple service enclosures (with PV in one of them) then you have a supply side connection? Is there anything your mind that make a 230.40 ex 2 with a load side PV then?
 
Maybe I missed it, but what is the upside in treating a PV line side connection under 230.40 exception #2 instead of exception #5?

Cheers, Wayne
No practical difference, just simplicity and consistency. 230.40 #2 is a long established and very commonly used practice, avoids having "normal disconnecting means" and the ambiguous "PV disconnect" and the confusion in nomenclature and grounding that goes along with it. Some POCOs have an aversion to line side perhaps because they think its a "tap". Why introduce more terms and articles when something call simply fall under an existing article?
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
Yes I am proposing "outlawing" line side connections, but again its just semantics. I still seem to not be getting my point accross. I am open to the possibility that I am overlooking something and if so I would like to know what it is. Take a look at the drawing and #2 from my list. You both think that is a line side PV connection? I see that definitely as 230.40 exception #2 with a load side Pv connection. It seems like you guys are saying WHENEVER you have multiple service enclosures (with PV in one of them) then you have a supply side connection? Is there anything your mind that make a 230.40 ex 2 with a load side PV then?
We aren't communicating, obviously. You are talking about code exceptions and I am talking about whether or not the conductors with which I am interconnecting are protected by the customer's OCPD. If not I don't see how you can call it a load side connection, but you can call it anything you like as long as I can still connect to the line side of a customer's OCPD(s).
 
We aren't communicating, obviously. You are talking about code exceptions and I am talking about whether or not the conductors with which I am interconnecting are protected by the customer's OCPD. If not I don't see how you can call it a load side connection, but you can call it anything you like as long as I can still connect to the line side of a customer's OCPD(s).
bottom line is there is always an OCPD. You are never connecting to unprotected conductors. You are just calling that OCPD a PV disconnect, I am calling it a service disconnect per 230.40 Ex 2. Its the same thing. The PV stuff is on the load side of whatever you call that OCPD, so everything is a load side connection if you think about it that way.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
bottom line is there is always an OCPD. You are never connecting to unprotected conductors. You are just calling that OCPD a PV disconnect, I am calling it a service disconnect per 230.40 Ex 2. Its the same thing. The PV stuff is on the load side of whatever you call that OCPD, so everything is a load side connection if you think about it that way.
Well, of course service conductors are protected somewhere upstream of the customer's OCPD but the available current is usually so much higher than the ampacity of the service conductors that they may as well not be. Call them "underprotected" if you like.

If I am connecting ahead of the customer's OCPD I can usually connect a much larger PV system than I could behind it; that's my only concern, that I can continue to do that. Whatever perambulations you guys go through with the language of the code isn't on my radar as long as you don't remove that option from my designs.
 
Well, of course service conductors are protected somewhere upstream of the customer's OCPD but the available current is usually so much higher than the ampacity of the service conductors that they may as well not be. Call them "underprotected" if you like.

If I am connecting ahead of the customer's OCPD I can usually connect a much larger PV system than I could behind it; that's my only concern, that I can continue to do that. Whatever perambulations you guys go through with the language of the code isn't on my radar as long as you don't remove that option from my designs.
Using 230.40 ex 2 to install another service disconnect and making a load side connection to that would offer the same capacity as a supply side connection.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
Using 230.40 ex 2 to install another service disconnect and making a load side connection to that would offer the same capacity as a supply side connection.
But it would require that we treat them all as new services with the N-G bond in the disco and all that entails. It would make residential systems thus connected harder to install. I'm not for it.

I don't see anything dangerous in pulling the EGC through the disco and keeping N and G separate in the disco. IMO this is a solution looking for a problem.
 
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kwired

Electron manager
Location
NE Nebraska
I have ,mentioned this before, but one potential way to get around a silly utility requirement like "no line side taps/interconnections in the meter/CT cabinet" is bring out another set of conductors to feed another service disconnect per 230.40 Exception 2 and make a load side connection in it qualifying the bus under 705.12(D)(2)(3)(c). Its really the same thing, but use a panelboard grouped with the existing one to make it "look like" a typical 230.40 ex 2 install.
My thoughts as well, just add another service disconnect is probably simplest way to handle this. Didn't look it up, but might even be allowed to be one of those disconnects that is allowed beyond the basic rule of only six allowed.
 
But it would require that we treat them all as new services with the N-G bond in the disco and all that entails. It would make residential systems thus connected harder to install. I'm not for it.

I don't see anything dangerous in pulling the EGC through the disco and keeping N and G separate in the disco. IMO this is a solution looking for a problem.
Fair point. Many (most?) areas treat the supply side disco as a service disconnect so one does the GEC anyway. One would use the tap method or common location method for the GEC and it wouldnt be much of a difficulty most of the time. Really, I dont see why the PV disco should be treated differently that an additional service disconnect enclosure so I would be happy to see harmonization there. What really should happen, IMO is the GEC connection requirements should be more lax so the existing GEC in the existing service disconnect would be sufficient. I dont see what is gained by moving the GEC connection a foot away to the outside of the service disconnect and reconnecting it there to comply with the "common location" provision (250.64(D)(3))
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
Fair point. Many (most?) areas treat the supply side disco as a service disconnect so one does the GEC anyway.
I cannot speak for what happens elsewhere, but everywhere in Texas with the exception of CPS in San Antonio and one or two other very small AHJ's, supply side interconnections are just a disco connected on the line side via IPC's and an EGC run through it from the service to the array.
 
I cannot speak for what happens elsewhere, but everywhere in Texas with the exception of CPS in San Antonio and one or two other very small AHJ's, supply side interconnections are just a disco connected on the line side via IPC's and an EGC run through it from the service to the array.
Well, clearly, in the interests of code simplification and harmonization you need to take one for the team and support my proposal 😅
 

djd

Member
My apologies to the OP for getting


And my apologies to the OP if he considers the discussion between gunny and I as off topic. I have made a connection in a CT cabinet before. There are no issues other than utility rules.
I would like to know why and to the original poster the same question , why do you think you need too what am I missing no room in the panel ?
 
I would like to know why and to the original poster the same question , why do you think you need too what am I missing no room in the panel ?
There are restrictions on the amount of current one can feed into a busbar in a panelboard where there are multiple sources. Thus branching off the existing service conductors with another set is often done instead of modifying or replacing the panelboard.

As far as why connect into the CT cabinet: it is likely an easy convenient place to create a new set of conductors vs setting a box and making a splice.
 
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