Rooftop discos - articles 225.32 & 690.14

[So Cal]

I'm having trouble getting signed off by a local building dept. The reason is that an Enhase microinverter system I installed has conduit that runs through the attic, they quote article 225.32 saying that the micros are a feeder and we need to add disco's where the conduit enters the building. I sent them a report from Enphase ( http://enphase.com/support-north-america/downloads/ ) under studies & White papers - "connectors as A/C disconnects...." that I thought would answer and I sent a copy of 690.31 (E) which, although it refers to DC circuits needing to be in metal raceways, states where the disconnect needs to be (not on the roof). They are unsure and won't approve the pv system as installed. They said they would have to get some word of authority on this as their concern is article 225.32 and their concept of a disco doesn't include "Connectors as A/C disconnects"


I could just comply and add the discos, but I feel responsible to get this building dept sorted out. We are all on the same page here in that we want safe systems etc. Plus it's a big fancy house & the discos won't look good.(the PV modules are grouped on 4 spots w/4 places that conduit enters the attic)

I don't seem to have the altitude of authority or the concise code references or explanation to satisfy them. Any suggestions?

 

[ggunn]

I'm having trouble getting signed off by a local building dept. The reason is that an Enhase microinverter system I installed has conduit that runs through the attic, they quote article 225.32 saying that the micros are a feeder and we need to add disco's where the conduit enters the building. I sent them a report from Enphase ( http://enphase.com/support-north-america/downloads/ ) under studies & White papers - "connectors as A/C disconnects...." that I thought would answer and I sent a copy of 690.31 (E) which, although it refers to DC circuits needing to be in metal raceways, states where the disconnect needs to be (not on the roof). They are unsure and won't approve the pv system as installed. They said they would have to get some word of authority on this as their concern is article 225.32 and their concept of a disco doesn't include "Connectors as A/C disconnects"


I could just comply and add the discos, but I feel responsible to get this building dept sorted out. We are all on the same page here in that we want safe systems etc. Plus it's a big fancy house & the discos won't look good.(the PV modules are grouped on 4 spots w/4 places that conduit enters the attic)

I don't seem to have the altitude of authority or the concise code references or explanation to satisfy them. Any suggestions?

You don't need a disco on the roof. The inverters' conformance to UL1741 ensures that when the AC disconnecting means at the point of interconnect is opened, the AC circuit is dead all the way back to the inverters. A disco on the roof would only shut down the lines between the disco and the inverters while leaving the conductors between the disco and the interconnect energized.

 

[GoldDigger]

You don't need a disco on the roof. The inverters' conformance to UL1741 ensures that when the AC disconnecting means at the point of interconnect is opened, the AC circuit is dead all the way back to the inverters. A disco on the roof would only shut down the lines between the disco and the inverters while leaving the conductors between the disco and the interconnect energized.

DC disconnects are more of a contentious issue, since the panel DC production is self-contained, but on the AC side with microinverters as with string inverters there will be no AC voltage at the inverter once it has been disconnected from the grid. The code addresses the DC disconnect separately for this reason among others.

 

[Zee]

The Code uses terms such as Photovoltaic System Disconnect in ways that may confuse them. They seem to refer at times to AC discos at times to DC. They are defined terms. If you spend the time on 690 you will see that no AC disco is needed.

This question, "when inverter output enters building envelope do i need a disco?" IS common, And often answered wrong as in "Yes, you do".
It was an issue even with string inverter output circuits.

I am sure the inspector reads "PV SYS DISCO" in the NEC to mean the disco you often need at the service interconnect (PV BREAKER or switch).
It is not.

These circuits, in addition, really are no different from AC branch circuits.
These are NOT "PV source circuits" , again another critical defined term.

IF you get nowhere: consider a two pole switch (240 Vac) over a bell box under a panel attached to a rail. For aesthetics. With an outdoor metal switch cover.

 

[augie47]

This is not an opinion, but an observation as I am still attempting to learn Art 690. That said Art 225.31 and 225,32 seem pretty definite without any exception to PV systems.

 

[GoldDigger]

This is not an opinion, but an observation as I am still attempting to learn Art 690. That said Art 225.31 and 225,32 seem pretty definite without any exception to PV systems.

OK, Let me try an exercise in code lawyering. Please give me a thorough critique:

A. There does not have to be an exception within 225 itself for PV because the following is found in 690:

690.3 Other Articles. Wherever the requirements of other articles of this Code and Article 690 differ, the requirements of Article 690 shall apply and, if the system is operated in parallel with a primary source(s) of electricity, the requirements in 705.14, 705.16, 705.32, and 705.143 shall apply.

Where does a disconnect have to be according to 690? There are several references which have to be linked together:
B. First, 690.31(E)

690.31
(E) Direct-Current Photovoltaic Source and Output Circuits Inside a Building. Where dc photovoltaic source or output circuits from a building-integrated or other photovoltaic system are run inside a building or structure, they shall be contained in metal raceways, Type MC metal-clad
or metal enclosures from the point of penetration of the surface of the building or structure to the first readily accessible disconnecting means.
The disconnecting means shall comply with 690.14(A)and(D).
The wiring methods shall comply with the additional
installation requirements in (1) through (4)

Looks like under some conditions, the disconnecting means can be remote from the point of penetration.

C. 690.14(C)

(C) Requirements for Disconnecting Means. Means shall be provided to disconnect all conductors in a building or other structure from the photovoltaic system conductors.
(1) Location. The photovoltaic disconnecting means shall be installed at a readily accessible location either on the outside of a building or structure or inside nearest the point of entrance of the system conductors.
Exception: Installations that comply with 690.31(E) shall be permitted to have the disconnecting means located remote from the point of entry of the system conductors.

That looks promising. But now we need to look at 690.14 (A) and (D)

D.

690.14 Additional Provisions. Photovoltaic disconnecting means shall comply with 690.14(A) through (D).


(A) Disconnecting Means. The disconnecting means shall not be required to be suitable as service equipment and shall comply with 690.17.

...so far so good....

E.

(D) Utility-Interactive Inverters Mounted in Not-Readily-Accessible Locations. Utility-interactive inverters shall be permitted to be mounted on roofs or other exterior areas that are not readily accessible. These installations shall comply with (1) through (4):
(1) A direct-current photovoltaic disconnecting means shall be mounted within sight of or in the inverter.
(2) An alternating-current disconnecting means shall be mounted within sight of or in the inverter.
(3) The alternating-current output conductors from the inverter and an additional alternating-current disconnecting means for the inverter shall comply with 690.14(C)(1).
(4) A plaque shall be installed in accordance with 705.10.

And we are now very close. (3) lets the additional disconnecting means be remote, provided there is also an AC disconnecting means in sight of the inverter(s).
But (2) requires means local to the inverter. What could that be?

F. Home stretch:

690.6 Alternating-Current (ac) Modules.
(A) Photovoltaic Source Circuits. The requirements of Article 690 pertaining to photovoltaic source circuits shall not apply to ac modules. The photovoltaic source circuit, conductors, and inverters shall be considered as internal wiring of an ac module.
(B) Inverter Output Circuit. The output of an ac module shall be considered an inverter output circuit.
(C) Disconnecting Means. A single disconnecting means, in accordance with 690.15 and 690.17, shall be permitted for the combined ac output of one or more ac modules. Additionally, each ac module in a multiple ac module system shall be provided with a connector, bolted, or terminal- type disconnecting means

The local AC disconnecting means for the inverters, required by 690.14 can be the AC wiring harness connector at that inverter.

The additional disconnecting means is now the one which is required to be readily accessible and is allowed to be remote from the penetration.

QE(hopefully)D.

 

[ggunn]

OK, Let me try an exercise in code lawyering. Please give me a thorough critique:

A. There does not have to be an exception within 225 itself for PV because the following is found in 690:


Where does a disconnect have to be according to 690? There are several references which have to be linked together:
B. First, 690.31(E)

Looks like under some conditions, the disconnecting means can be remote from the point of penetration.

C. 690.14(C)

That looks promising. But now we need to look at 690.14 (A) and (D)

D.
...so far so good....

E.

And we are now very close. (3) lets the additional disconnecting means be remote, provided there is also an AC disconnecting means in sight of the inverter(s).
But (2) requires means local to the inverter. What could that be?

F. Home stretch:

The local AC disconnecting means for the inverters, required by 690.14 can be the AC wiring harness connector at that inverter.

The additional disconnecting means is now the one which is required to be readily accessible and is allowed to be remote from the penetration.

QE(hopefully)D.

Looks good to me, although common sense gets you there a lot quicker.

A DC disco on the roof de-energizes the conductors going through the building but an AC disco up there does not.

 

[jaggedben]

225 Part II is about feeders and branch circuits that originate in a building or structure that is different from the one they supply. Unless a PV system is connected to such a circuit, or unless it is a stand-alone system, that entire section has no relevance. As long as the PV system already has a disconnecting means on the structure where it is located, 225.31 and .32 don't require another one.

 

[So Cal]

If I had to go the route of convincing the AHJ myself I would have been very well armed, thanks to you fine gentlemen. What I did to handle it was to hook him up with someone that he felt had altitude. Who in this case was the Los Angeles Building Dept's resident Solar Guru and Senior Electrical inspector. Who only needed 2 words "Not needed"

Thanks though!

 

[Zee]

Glad the solar guru gave his blessing

Jben, agreed 225.31 and .32 doesn't apply. If it did, every outdoor light or outlet would need a disco at the wall!

GoldDigger,
Great points.
A. Good point about 690 precedence over many other code sections. I'll remember that.
B. 690.31(E) Does not apply to AC discos.

It is somewhat poorly written and has caused so much misreading.
The confusion stems from the term "dc photovoltaic" not being repeated in a redundant fashion to describe BOTH source and output circuits in this sentence.
Also "output circuit" sounds a lot like "inverter output circuit".
In other words, the phrase,
"Where dc photovoltaic source or output circuits...."
Should read:
"Where dc photovoltaic source or * dc photovoltaic * output circuits........"
It is more clear when backing up and seeing that the heading is titled "DC...."

On the other hand: "Inverter output circuit" is a defined term, and always used as such, elsewhere when AC discos are in fact under discussion.


I agree with your ultimate conclusion:
Yup, the connectors are the AC switches in line of sight.
BUt they cannot get authority from the heading titled AC Modules. These are inverters. (we both know they are functionally equivalent, but different Code treatment)

GGUNN: yeah, true that, an ac disco could even give a novice a false sense of safety when mounted on a rooftop. Utility is still live.....

 

[GoldDigger]

Yup, the connectors are the AC switches in line of sight.
BUt they cannot get authority from the heading titled AC Modules. These are inverters. (we both know they are functionally equivalent, but different Code treatment)

Thanks Zee.
There is no direct mention of micro inverters in the code. But they do talk about AC modules and mention that any interconnecting DC wiring is considered internal to the module and therefore none of the DC related rules apply. Depending on who you talk to, a normal panel wired by the installer to a micro inverter may be described as an AC module. If the panel and microinverter are connected together by a manufacturer instead of the installer, then most would agree that it is an AC module. Yet another opportunity for clarification in future code cycles.

 

[jaggedben]

B. 690.31(E) Does not apply to AC discos.

Except for something very stupid, namely that 690.14(D)(3), which specifically refers AC disconnects, refers to 690.14(C)(1) which in turn has an exception referring to 690.31(E).

I highly doubt this was intentional on the part of the CMP. The reference to 690.14(C)(1) should be changed to refer to 705.21 and 705.22. Either that, or the entire content of 690.14(D) should be removed and replaced with a simple reference to 705.70.

It is somewhat poorly written and has caused so much misreading.

Totally agree.

 

[Zee]

Well, you certainly know this issue well, Jben. I didn't know all the Code references that well, but i agree that their intention was never to have 690.31 (E) apply to AC.

GoldDigger,
Hey, no problem.
I want to treat micro.s + modules = ac mod.s, i just am not allowed to.:weeping:
Also Wiles strongly disagrees. And i pretty much just bow down to whatever he says.
AC modules need to be such that you never touch or connect the dc connectors /conductors, as far as i remember. And i agree that means factory built as one unit, liek you said.
IF ac mod. = micro + panel field installed, i could skip the GEC.
When they wrote COde re. AC Mod.s, true Ac mod.s had yet to be made.
Hence all the wording like "True" AC module when mfctrs describ etheir product..

 

[jaggedben]

The code definition for AC modules includes the phrase "environmentally protected". If a module has exposed DC wiring (factory assembled or not), is it "environmentally protected"? Seems like it's up to the AHJ.

 

[GoldDigger]

The code definition for AC modules includes the phrase "environmentally protected". If a module has exposed DC wiring (factory assembled or not), is it "environmentally protected"? Seems like it's up to the AHJ.

If the exposed wiring is PV, then it is as protected as it is required to be when up on the roof. But does that count?

 

[ggunn]

The code definition for AC modules includes the phrase "environmentally protected". If a module has exposed DC wiring (factory assembled or not), is it "environmentally protected"? Seems like it's up to the AHJ.

That has no bearing on the question at hand. An AC disco on the roof in an Enphase system would not make it any safer.

 

[jaggedben]

That has no bearing on the question at hand. An AC disco on the roof in an Enphase system would not make it any safer.

We all know a disco doesn't make things safer. The question is whether it's required by code.

 

[ggunn]

We all know a disco doesn't make things safer. The question is whether it's required by code.

Yeah, there I go again trying to use common sense...