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Required Safety devices NEC 2020 code Powerwall installation

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doesn't the powerwalls and solar still power the house with the proposed system? gateway thinks utility is down and powerwalls and solar keep working. utility worker is safe, but not the fireman. solar is hot as well as house...
or am i wrong? i've seen tesla installs just like this on the net...
Yes, that is the core of my concern. ESS is required to be shut down from the exterior of the home.
Add a remote battery disconnect at the location of the rest of the service disconnects. This will take down the ESS, which will take down the PV as soon as the grid drops or the main breakers are opened.
 
does the emergency shutdown switch use a EOL resistor? (end of line)
that way if the wire short out (due to fire) the system will shut down...
I do not know the answer to this. Tesla might know, but since it is not code required I doubt it is implemented.

We use a double shielded TC-ER wire in conduit for our ESS disconnect buttons. This wire could still be melted internally but it would take a lot more heat than a simple twisted pair, or an exposed control cable.
 
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Tesla says the big red button only works for pw2+. So this is what they came up with, installing a second 400 amp panel outside to shut down the system.
They are installing inverter inside, perhaps they need another disconnect switch inside the garage for the Tesla inverter.
So Fort Worth want a outside service disconnect for the left non backup panel outside. Does anyone have a recommendation for a service disconnect fort two 200 amp panels? Combining the blade disconnect and the service disconnect.
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Tesla says the big red button only works for pw2+.
This confuses me. Are they saying that the regular Tesla Solar Inverter doesn't include provisions for wiring in a Rapid Shutdown Initiation switch? I could not find the installation manual for the regular Tesla Solar Inverter, but the one picture of the innards I found look identical to the diagram of the Solar portion of the PW+ innards in the PW+ installation manual. Including the Rapid Shutdown Initiation connections.

There's no requirement to have one device that initiates shutdown of both the PWs and the solar inverters. So you could have two big red buttons side by side. The Backup Gateway 2 certainly supports a big red button, and I would be very surprised based on the above if the Tesla Solar Inverter doesn't support a big red button. And I would expect your existing PV system can stay as is, whatever its Rapid Shutdown compliance status is.

Cheers, Wayne
 
i would think the big red button would shutdown the Powerwalls and the solar would shutdown on its own since it is not grid forming.
There's 3 power sources--grid, PW, and PV. Killing both grid and PW will kill PV, as it is not grid forming. But the PW big red button just kills the PWs, it doesn't disconnect from the grid, so the PV would still be running. If the PW big red button also opened the GW disconnecting the backed up loads from the grid, that would kill the PV, but the effect is that all your backed up loads would be unpowered. Which would be undesirable when you want to just service the PV, say.

The NEC requires that you have: 1-6 breakers that when you turn them off you disconnect from the grid ; a button/switch that will kill the PWs; and a button/switch that will kill PV. The buttons need to individually achieve the specified deenergization regardless of the state of the other buttons or service disconnects.

Cheers, Wayne
 
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Tesla says the big red button only works for pw2+. So this is what they came up with, installing a second 400 amp panel outside to shut down the system.
They are installing inverter inside, perhaps they need another disconnect switch inside the garage for the Tesla inverter.
So Fort Worth want a outside service disconnect for the left non backup panel outside. Does anyone have a recommendation for a service disconnect fort two 200 amp panels? Combining the blade disconnect and the service disconnect.View attachment 860497View attachment 860498
This whole question can get pretty complicated especially when you include the utility requirements. There is no single enclosure I know of that would be both a bladed lockable disconnect and a second breaker enclosure.

I do not know about your area, but around here the utility sometimes requires a bladed AC disconnect from a short list of approved AC disconnects. Regardless of whatever else happens, this bladed AC disconnect needs to be on the list and interrupt current back to the utility.

I know almost nothing about your location, AHJ and design, but if I was blindly asking questions I might ask why not put the 200A disco W in between the TEG and the generation sources? Interrupting the AC feed between the Powerwall+PV and the GW2 will shutdown the batteries and the PV in one handle. Then the 400A sub doesn't need to be outside and the 200A main breaker in the TEG becomes the exterior means of disconnect for the loads once the disconnect handle is turned off to shutdown the backup system and in either order.

What is objectionable to you about the current design? Number of panels, location of them, both?

I also don't really understand why not just land all the PV inside the same sub as the Powerwalls are landing in. Must be a location thing? Why have the second 400A subpanel V at all? Are there existing loads along with the 100A subfeed with the existing solar?

In my perfect mind, the 200A subfeed to the existing loads subpanel to be backed up can just also land in panel Y instead of the TEG lugs, and then no main breaker is needed in either (or the one) of the 400A subpanels.

I am sure there are things I missed here as I really didn't dive too deep into this.
The NEC requires that you have: 1-6 breakers that when you turn them off you disconnect from the grid ; a button/switch that will kill the PWs; and a button/switch that will kill PV. The buttons need to individually achieve the specified deenergization regardless of the state of the other buttons or service disconnects.

Cheers, Wayne
Not sure if my plan above accomplishes what you are trying to say, but many local AHJ has accepted a 2 or 3 step process to shut things down. Do you have some code to support the interpretation about each button/switch needs to act independently? We typically put the process on a placard and put that placard obviously on the Service and Power sources if not in line of sight.
 
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Not sure if my plan above accomplishes what you are trying to say, but many local AHJ has accepted a 2 or 3 step process to shut things down. Do you have some code to support the interpretation about each button/switch needs to act independently?
Well, mostly I was trying to say that there's one section that requires a service disconnect (in Article 230), another that requires a PV rapid shutdown initiation device (in Article 690), and another that requires an ESS shutdown device (in Article 706).

I don't mean to say that a single device can't perform more than one of those functions, but I don't see the language in 690.12(C) as allowing rapid shutdown initiation for a single PV system to be accomplished by more than 1 action (e.g. throwing two switches). If you have multiple PV systems (multiple inverters, say), each one could have its own rapid shutdown initiation device, to my reading.

(2020) 706.15(A)'s language is a bit less clear, but it does refer to "the" disconnect for an ESS. [Apparently 705.16(A)'s language about a readily accessible ESS disconnect outside the building for one and two family dwellings is new for 2020?]

Cheers, Wayne
 
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Well, mostly I was trying to say that there's one section that requires a service disconnect (in Article 230), another that requires a PV rapid shutdown initiation device (in Article 690), and another that requires an ESS shutdown device (in Article 706).

I don't mean to say that a single device can't perform more than one of those functions, but I don't see the language in 690.12(C) as allowing rapid shutdown initiation for a single PV system to be accomplished by more than 1 action (e.g. throwing two switches). If you have multiple PV systems (multiple inverters, say), each one could have its own rapid shutdown initiation device, to my reading.

(2020) 706.15(A)'s language is a bit less clear, but it does refer to "the" disconnect for an ESS. [Apparently 705.16(A)'s language about a readily accessible ESS disconnect outside the building for one and two family dwellings is new for 2020?]

Cheers, Wayne
I only had really reviewed 2017 code to this point on rapid shutdown, but the below discussion isn't specific to this job.

Loss of AC (grid) power is typically accepted as a means of PV rapid shutdown but when you have a battery then there may be an instant or delayed reconnection of the PV when the island is created. I would try to argue that eliminating the multiple sources of power calls for disconnecting each one, though I might lose lol. When there are 2 other sources of power like an ESS and grid this seems reasonable for there to be 2 switches. I see the 2017 RSD code doesn't have the same 2020 language that says it must be a single switch for a single PV system, so my argument gets really bad Jan 1.

The 2020 NEC 690.12.C does start off that "The initiation Device(s) shall initiate rapid shutdown function of the PV system." So it is clear multiple devices are allowed. However, the later sentence (new to 2020) seems to imply that this must be a single switch "For a single PV system the rapid shutdown shall occur by the operation of any single initiation device. Devices shall consist of at least one or more of the following: 1. Service Disconnecting Means 2. PV System Disconnecting means 3. Readily accessible switch that plainly indicates in the on or off position.

As far as the new section of 706.15(A) there was no requirement in 2017 to have an exterior ESS disconnect for 1 and 2 family dwellings, so that part is all new.

When talking about the ESS disconnect, we have to talk about multiple disconnects since that is the way the NEC defines ESS. 706.2 says that an ESS is one or more components assembled together. The Tesla Powerwall 2 AC, is AC coupled multimode system with up to 10 ESS components possible. The 30A breaker for each Powerwall is the ESS disconnect, and the disconnect feeding the TEG on the grid side is the Interactive system disconnect.

I do not think the 2020 code intends that I provide a single breaker where someone could turn off every of the ESS on the exterior of the building with a single switch. However it would be quite confusing if I placed single Powerwalls all around the building, with a separate disconnect next to each of them and no other obvious way to shut all of the ESS down, though it may be code compliant. To make matters worse, the Tesla Powerwall signal light doesn't obviously change colors or flash rapidly or anything when it is shutdown. Firefighters hate that! How do they know they found and turned off 5 batteries assuming they arent grouped and the lights do not change regardless?

It's clear that the fire service has a part to play here as emergency responders and they unfortunately get input later, or not at all. My design practice is to always use the fewest switches possible and less than 6, group them together and put disconnects at or in sight of the service wherever possible. I prefer using the battery disconnect button to make an easy shutdown procedure for the first responders whenever possible (hit the button and turn off the main in any order). However if someone accidentally presses it while the grid is down, it is usually a service call to 12v jump the system and wake it up. For whatever reason people often bump the button or maybe they press it because they can't help themselves.

Ah, disconnect discussions are some of my favorites, I guess I have a lot to say about this lol.
 
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Loss of AC (grid) power is typically accepted as a means of PV rapid shutdown but when you have a battery then there may be an instant or delayed reconnection of the PV when the island is created. I would try to argue that eliminating the multiple sources of power calls for disconnecting each one, though I might lose lol. When there are 2 other sources of power like an ESS and grid this seems reasonable for there to be 2 switches. I see the 2017 RSD code doesn't have the same 2020 language that says it must be a single switch for a single PV system, so my argument gets really bad Jan 1.
While the language isn't as explicit in 2017, I'd say it's still implied that with one PV system, you only get one initiation device. Your interpretation would mean "one PV system, unlimited initiation devices; multiple PV systems, up to 6 initiation devices," which is nonsensical. So I take the language on "multiple systems can have up to 6" to imply that a single system can only have 1.

the disconnect feeding the TEG on the grid side is the Interactive system disconnect.
I don't see that as a code required disconnect, since it doesn't shut anything off.

BTW, apparently the big red button connected to the TEG does not satisfy 2020 706.15(B), as while it will put the PWs into a safe mode (per the manual), it does not actually activate the disconnect, which per 706.15(A)(3) has to be "lockable open". But a big red button could activate multiple shunt trip breakers, which could have permanently installed means to be locked open.

However it would be quite confusing if I placed single Powerwalls all around the building, with a separate disconnect next to each of them and no other obvious way to shut all of the ESS down, though it may be code compliant.
See also Article 710, including 710.10.

Cheers, Wayne
 
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While the language isn't as explicit in 2017, I'd say it's still implied that with one PV system, you only get one initiation device. Your interpretation would mean "one PV system, unlimited initiation devices; multiple PV systems, up to 6 initiation devices," which is nonsensical. So I take the language on "multiple systems can have up to 6" to imply that a single system can only have 1.
Well my interpretation is more like "To shut down all sources of power you might need that many switches."

I don't see that as a code required disconnect, since it doesn't shut anything off.
That breaker shuts down the loads from the exterior of the building per 2020 NEC 230.85, it's just that then another system comes on and re-energizes those loads. At that point you need to shut down both systems.

BTW, apparently the big red button connected to the TEG does not satisfy 2020 706.15(B), as while it will put the PWs into a safe mode (per the manual), it does not actually activate the disconnect, which per 706.15(A)(3) has to be "lockable open". But a big red button could activate multiple shunt trip breakers, which could have permanently installed means to be locked open.

From my understanding, the button activates the same internal relay as the switch on the side of the Powerwall. However finding a button that is lockable and plainly indicates on or off is a challenge, unless you give pretty wide definitions of lockable and plainly indicate. In some cases, we do use shunt trip breakers instead of the TEG button.
 
My certified Tesla installer put in a separate switch outside for each of our 3 batteries. So, in an emergency, 1 breaker (grid) and 4 handles must be thrown (PV + 3 PWs). I asked about putting in a single switch for all 3 PWs but they wouldn't do it. Would probably run out of wall for breakers if I had as many PWs as @h2ofun
 
My certified Tesla installer put in a separate switch outside for each of our 3 batteries. So, in an emergency, 1 breaker (grid) and 4 handles must be thrown (PV + 3 PWs). I asked about putting in a single switch for all 3 PWs but they wouldn't do it. Would probably run out of wall for breakers if I had as many PWs as @h2ofun
Yep, and if I install 2 more batteries, 2 more handles will be squeezed in
 
Well my interpretation is more like "To shut down all sources of power you might need that many switches."
That's not for all sources of power, just for the PV Rapid Shutdown. You could also have up to 6 switches to disconnect the grid (per service), and then an apparently unlimited number to turn off any ESSs.

That breaker shuts down the loads from the exterior of the building per 2020 NEC 230.85, it's just that then another system comes on and re-energizes those loads. At that point you need to shut down both systems.
A (or rather the upstream-most) breaker that kills all the grid power is certainly an NEC required disconnect. But I don't see a feeder breaker supplying the TEG with grid power as a disconnect that satisfies some NEC code section. If it is, what code section? E.g. consider the case of a service panel with a 400A bus, a 200A main breaker/service disconnect, various load breakers, and feed thru lugs supplying the TEG. Is it missing an NEC required disconnect?

As to the TEG "big red button," if it's lockable open (or a lockable open version can be had), on reflection, it sounds like it could be a single 706.15 disconnect for all the PWs connected to that TEG. That also makes think that perhaps a TEG plus its PWs should be considered a single ESS.

Cheers, Wayne
 
Tesla says the big red button only works for pw2+. So this is what they came up with, installing a second 400 amp panel outside to shut down the system.
They are installing inverter inside, perhaps they need another disconnect switch inside the garage for the Tesla inverter.
So Fort Worth want a outside service disconnect for the left non backup panel outside. Does anyone have a recommendation for a service disconnect fort two 200 amp panels? Combining the blade disconnect and the service disconnect.View attachment 860497View attachment 860498
Resurrecting this because I tried to order this 400A load center BR1224L400R, and tech support says that there is no way to retain a 200A backfed main breaker BJ2200. I wonder how Tesla manages this or if they just don't bother retaining the main?