ESS Disconnects and 2017 NEC 705.22

[Vines41]

I am an ESS installer and am in discussion with an AHJ about whether or not a locking device is needed for AC Coupled energy storage systems (ESS). I also want to understand more about when locking open is required, what satisfies this requirement? I am specifically looking at the Tesla Powerwall, but I imagine other AC Couples ESS are similar. We are under the 2017 NEC (2019 CEC)

These AC coupled Energy Storage Systems have a UL 1741 listed inverter as part of them, so they shutdown very quickly when the breaker that feeds them is opened. I understand this anti-islanding feature to be the reason why PV circuits are often not required by many AHJ to add a locking disconnect, though some still do require it.

When locking the disconnect is required by the AHJ, what sort of equipment satisfies the requirements of 110.25?
1. It is pretty clear that Bladed Disconnects are allowed, but they are a bit large and ugly. We could use them with only the aesthetic issues, but those are significant with many of our customers.
2. Locking the enclosure seems somewhat reasonable, except for 705.22 (3) indicates this won't allow the user to see whether the breaker is still in the off position.
3. Using add-on breaker accessories like the BRLW below should be compliant in my eyes, but the local AHJ will not allow it. They are requiring the bladed lockable disconnects only.

 

[wwhitney]

3. Using add-on breaker accessories like the BRLW below should be compliant in my eyes, but the local AHJ will not allow it. They are requiring the bladed lockable disconnects only.

What is their code citation and reasoning? Or are they just being irrational?

Cheers, Wayne

 

[Vines41]

At first I got a general callout to 706.7 Only (2) seems to require locking, and this case does not apply since we are talking about the breaker within sight of the Powerwall. I pushed back and have argued this point.

When I pushed in another jurisdiction I have come up against the wall of 705.22, so I suspect this is the next pushback. The 2 jurisdictions talk extensively and seem to come up with similar requirements within weeks of each other.

NEC 2020 706.15(A)(3) seems to obviously require it, so looking forward does not support the lack of locking disconnects.

 

[wwhitney]

I was specifically asking about the code citation and reasoning for requiring a bladed disconnect, rather than a breaker accessory like the BRLW you post a photo of.

The latter are generally understood to be sufficient for disconnects that are required to be "capable of being locked in the open position in compliance with 110.25." If they were not, we'd be seeing lots of bladed disconnects for things like hard-wired dishwashers (see 422.31).

Cheers, Wayne

 

[Vines41]

I do not have any further citation for that, though I did quote 110.25 and bring up the specific accessories in question.

The AHJ seems to allow a breaker lock that is a part of the breaker housing. Here is the exact wording they used regarding the BRLW
"This item does not work, since it is easily removed and is not a permanent part of the disconnect."

 

[wwhitney]

My response (uninformed by your far more extensive experience dealing with AHJs) would be along the lines of:

"Manufacturer's breaker lock accessories are attached to the breaker body and are held in place by the panel cover. As such they can not be removed without removing the panel cover, in contrast with simple set screw breaker locks that attach only to the breaker handle. Manufacturer's breaker lock accessories are generally recognized as complying with 110.25, in contrast with set screw breaker locks, which do not.

Manufacturer's breaker lock accessories are commonly used for other "lockable open" disconnect requirements such as those in 422.31. The language there is semantically identical to the language in 705.22(7). Therefore if they meet the NEC requirements for a hardwired dishwasher, they meet the NEC requirements for an electric power production source."

Cheers, Wayne

 

[Vines41]

My response (uninformed by your far more extensive experience dealing with AHJs) would be along the lines of:

"Manufacturer's breaker lock accessories are attached to the breaker body and are held in place by the panel cover. As such they can not be removed without removing the panel cover, in contrast with simple set screw breaker locks that attach only to the breaker handle. Manufacturer's breaker lock accessories are generally recognized as complying with 110.25, in contrast with set screw breaker locks, which do not.

Manufacturer's breaker lock accessories are commonly used for other "lockable open" disconnect requirements such as those in 422.31. The language there is semantically identical to the language in 705.22(7). Therefore if they meet the NEC requirements for a hardwired dishwasher, they meet the NEC requirements for an electric power production source."

Cheers, Wayne

Thanks for the feedback Wayne, though I might point out that the UL489 standard for breakers does not allow them to be held in only by the deadfront.

The BRLW has some tabs where it requires needle nose pliers to install or remove.

 

[ggunn]

Do you have solar and batter(ies) combined in a generation panel? Would the AHJ accept a bladed, lockable AC disconnect on the output of the generation panel as compliant? We have had some success with that approach under similar circumstances.

 

[wwhitney]

Thanks for the feedback Wayne, though I might point out that the UL489 standard for breakers does not allow them to be held in only by the deadfront.

I was referring to the deadfront blocking the removal of the BRLW, which I assume is the case.

The BRLW has some tabs where it requires needle nose pliers to install or remove.

Totally worth informing the AHJ about that; that certainly does not count as "easy to remove" in my book. [Although "not easy to remove" is not part of the 110.25 requirements, just that "The provisions for locking shall remain in place with or without the lock installed."]

The most generous interpretation of the response you got is that the AHJ is confusing the BRLW with the style that falls off when you remove the lock, or possibly a style that can be removed with a regular screwdriver while the panel cover is still on (assuming that exists). The former doesn't comply with 110.25; and the latter is arguable.

Cheers, Wayne

P.S. Is BRLW the correct part number? I'm getting different pictures when I search on that.

 

[Vines41]

Do you have solar and batter(ies) combined in a generation panel? Would the AHJ accept a bladed, lockable AC disconnect on the output of the generation panel as compliant? We have had some success with that approach under similar circumstances.

That is a good point and one that I will explore after the current questions are responded to. The issue is the inspector is confusing the requirements in 706.7 (B) with 706.7 (E) and requiring the locking whenever the ESS are more than 5' away from the breaker that serves them.

 

[Vines41]

I was referring to the deadfront blocking the removal of the BRLW, which I assume is the case.


Totally worth informing the AHJ about that; that certainly does not count as "easy to remove" in my book. [Although "not easy to remove" is not part of the 110.25 requirements, just that "The provisions for locking shall remain in place with or without the lock installed."]

The most generous interpretation of the response you got is that the AHJ is confusing the BRLW with the style that falls off when you remove the lock, or possibly a style that can be removed with a regular screwdriver while the panel cover is still on (assuming that exists). The former doesn't comply with 110.25; and the latter is arguable.

Cheers, Wayne

P.S. Is BRLW the correct part number? I'm getting different pictures when I search on that.

I agree I just wanted to point out that according to the UL standard, locks attached to the deadfront are not compliant.

I mentioned at the beginning of this conversation with the AHJ the BRLW needed needle nose pliers to remove, and sent the attached datasheet and the picture previously. The comment above was my response.

 

[wwhitney]

I agree I just wanted to point out that according to the UL standard, locks attached to the deadfront are not compliant.

That's a long standard, do you have a section number to reference? I'm a bit surprised by this, as there are manual transfer mechanisms that consist solely of interlocks that are attached to the deadfront, including ones sold by panel manufacturers.

I mentioned at the beginning of this conversation with the AHJ the BRLW needed needle nose pliers to remove, and sent the attached datasheet and the picture previously. The comment above was my response.

This is where I am very thankful I don't do this professionally.

If I had to continue the conversation, I might go with "110.25 has no requirement that the provisions for locking meet some standard of being hard to remove or of being 'permanent.' BRLW will remain in place with or without a lock installed."

And of course the AHJ just decreed that all hardwired dishwashers have to have blade disconnects.

Cheers, Wayne

 

[Vines41]

I agree I just wanted to point out that according to the UL standard, locks attached to the deadfront are not compliant.

I mentioned at the beginning of this conversation with the AHJ the BRLW needed needle nose pliers to remove, and sent the attached datasheet and the picture previously. The comment above was my response.

It's on standard page 166. Its possible that the standard for manual transfer switches have other different requirements. The UL489 standard in question only deals with circuit breakers.

I think a lot of this is just because ESS are so new. I plan to have a 1-page document for the IAEI meeting that I can ask different people a few simple questions about exactly this issue.

 

[wwhitney]

It's on standard page 166.

Thanks, good to know. For the curious, I transcribed UL 489 14.8 below.

For your AHJ, you could try referencing UL 489 14.8 and that the BRLW, as a listed product, complies with those requirements. [So I might edit my previous proposed response to instead say "UL 14.8.1(b) specifies the required standard of difficulty of removal, which BRLW complies with."]

Hopefully having a UL standard to fall back upon will allow them to approve it (assuming they have any interest in being cooperative).

Cheers, Wayne


UL489, in part

14.8 Lock-off device

14.8.1 A lock-off device supplied as a kit for field installation shall comply with all of the following:

a) Accommodate a padlock that will prevent the operation of the circuit breaker or switch with the padlock in place;
b) Require the use of a tool for removal;
c) Have the necessary mechanical strength to ensure reliable and positive mechanical performance;
d) Not depend on the panel enclosure cover to retain the device in place;
e) Not interfere with the normal intended operation of the circuit breaker or switch;
f) Ensure that the ON-OFF marking for the circuit breaker or switch is clearly visible with the padlocking attachment in place; and
g) Be marked in accordance with 17.9.

 

[jaggedben]

The type of breaker lock devices you are referencing are compliant with all those requirements. I had an AHJ who wanted these for all our solar breakers for a while (unless there was a separate lockable disco) and they were absolutely fine with these. (For a while I knew all the part numbers for the different brands.)

They are being unreasonable and naive. Making the lock difficult to remove is not the point. An unscrupulous person can open up and rewire a bladed disconnect about as easily. The purpose of the locking requirement is to allow lock-out-tag-out procedures and to signal to responsible people not to turn the thing on. Anyone who removes the deadfront in order to remove the locking device knows they are doing something wrong, and anyone who wants to do something wrong isn't gonna be stopped by the features on a bladed disco either.

The breaker lock meets the letter and intent of the code and if they can't see that then you're SOL because there's no reasoning with them.

 

[Ridikuluz]

Under 2017 code I would argue that 705 applies only to power production sources operating in parallel with the utility. 706 does not require the disconnecting means to be lockable. An ESS is not power production equipment per NEC definitions. Under 2020, it is clear that you need a locking disconnect.

 

[jaggedben]

An ESS is not power production equipment per NEC definitions.

Well, yes it is, although I agree that 705 does not apply if it does not operate in parallel with a utility, because that is explicitly the scope of 705. And for what it's worth, this thread wasn't about a situation where 705 didn't apply. Also, the majority of ESS are interactive AC outputting sources, so they are subject to 705.

 

[pv_n00b]

It's an interesting point if ESS has to comply with 705.12 if connected to another energy source. Has anyone noticed that the 2017 NEC has 706.8 which requires that ESS connections to other energy sources comply with 705.12 but in 2020 the wording was deleted and a new 706.8 was created that has nothing to do with the old one? I looked in TerraView and there is nothing on why 706.8 was deleted, it just disappears. That makes me wonder if ESS is supposed to comply with 705.12?

 

[Ridikuluz]

@jagged ben:
Thank you for the response. I am partly playing devils advocate, because I think the lockable disconnect is a valid safety measure that should be installed as a best practice. However, is it required by code under 2017 requirements? Is an ESS generating power, or is it storing power for future use?

705.1 Scope
This article covers installation of one or more electric power production sources operating in parallel with a primary source(s) of electricity

Power Production Equipment. The generating source, and all distribution equipment associated with it, that generates electricity from a source other than a utility supplied service.

Informational Note: Examples of power production equipment include such items as generators, solar photovoltaic systems, and fuel cell systems.

 

[wwhitney]

If the ESS never generates electricity from the chemical potential energy inside of it, it's not a very useful device. It seems obvious to me it fits the scope you quoted.

Cheers, Wayne