"There's the battery"

[ICE]

The inspection was for a Tesla battery system that was added to an existing solar system. I asked the person that met me to "Walk me through the system". He pointed at the battery and said, "That's the battery". I said, "What's the rest of it all about". He said that this is the first inspection that he has ever been on and he knows nothing about anything that's electrical.

Correction number two had to do with a clearance issue. There's little doubt that the solar company will call the manager to complain about correction number one.

 

[steveray]

The inspection was for a Tesla battery system that was added to an existing solar system. I asked the person that met me to "Walk me through the system". He pointed at the battery and said, "That's the battery". I said, "What's the rest of it all about". He said that this is the first inspection that he has ever been on and he knows nothing about anything that's electrical.

Correction number two had to do with a clearance issue. There's little doubt that the solar company will call the manager to complain about correction number one.

Battery sticking out past the panel? Watch out for 702.4B on those...They connect full load typically here and it will not transfer..IF they are saying it works as standby....Which they do...

 

[wwhitney]

Watch out for 702.4B on those.

702.4(B) does not apply to a battery ESS with MID. The MID is not a Transfer Switch per the Article 100 definition. 710.15(A) is the applicable requirement.

Cheers, Wayne

 

[steveray]

 

[wwhitney]

[An image of text that is not excerptable for replying.]

Some of that enhanced content is correct, some is debatable. Let me back up my earlier post. Definitions from the 2023 NEC:

"Transfer Switch. An automatic or nonautomatic device for transferring one or more load conductor connections from one power source to another."
"Microgrid Interconnect Device (MID). A device that enables a microgrid system to separate from and reconnect to an interconnected primary power source."

From these definitions, we can see that an MID is not a Transfer Switch. The dual-mode inverters (which can function as grid-following or grid-forming) never disconnect from the load; only the primary source is connected or disconnected by the MID. It's the difference between a double throw switch and a single throw switch.

So as far as 702.4(B) goes, with an MID only, there is no transfer equipment. The last sentence of the commentary above would apply when the stand-alone system is connected via transfer equipment.

Also, the first half of the Scope 710.1 clearly covers inverter-based ESS once the MID has opened: "This article covers electric power production sources that operate in island mode . . ."

Cheers, Wayne

 

[sclavette]

It's being used as an optional standby system and the equipment is automatically transferring the power over, why wouldn't 702.4(B) apply as well? The commentary specifically says that they aren't mutually exclusive.

If you want to go one step further, who says that it has to be defined as one or the other?

It's one thing to use these strictly for offsetting high-rate utility periods. It's another to use them as generator replacements and no reason they shouldn't be held to the same code requirements. Most output 20-25A max and people have them set up to power an entire 200A service. The likelihood of overload is extremely high

 

[wwhitney]

It's being used as an optional standby system and the equipment is automatically transferring the power over

It's not, actually. It's typically not standing by, it's being used all the time to load shift as well as offer backup capability. And nothing transfers, it's permanently connected all the time. It really is a different use profile, so while I won't say it's apples and oranges compared to an engine generator, it's at least grapefruit and oranges.

Cheers, Wayne

 

[sclavette]

It's being sold here in the Northeast as backed up power.

 

[wwhitney]

It's being sold here in the Northeast as backed up power.

Sure, it provides back up power. But it does so without any transfer equipment, as per the definitions in post #5.

Cheers, Wayne

 

[mark handler]

 

[mark handler]

 

[ICE]

That’s a pair of batteries. Items associated with the electrical installation are allowed to stick past the front of the panel above by a maximum 6”.

Something else to watch out for is sunlight. Batteries are generally not allowed in direct sunlight. That’s an example of value engineering at its finest.

 

[wwhitney]

Something else to watch out for is sunlight. Batteries are generally not allowed in direct sunlight. That’s an example of value engineering at its finest.

Tesla's Powerwall 2 installation manual says "For hot climates Tesla recommends keeping Powerwall out of direct sunlight. Installation in full sun raises the temperature inside the enclosure above ambient temperature. This temperature rise is not a safety risk, but may impact battery performance."

So not an inspection concern for this product.

Cheers, Wayne

 

[ICE]

So not an inspection concern for this product.

Tesla has two warnings related to sunlight. The level of warning is a caution due to minor injury or damage to the equipment. The information is not presented as a recommendation. I wonder what Tesla considers a minor injury or damage. I have no issue with enforcing the caution as an installation instruction and therefore, code..

 

[wwhitney]

Tesla has two warnings related to sunlight. The level of warning is a caution due to minor injury or damage to the equipment. The information is not presented as a recommendation.

1) The lengthier section I quoted clarifies the terser Caution you quoted. It makes it clear that the issue is possible equipment damage, not safety. As such, I don't see it as enforceable at inspection.

2) I see "Avoid X" as a recommendation, and not the same as "Do not do X".

For example, we have the Red Warning that says "WARNING: Do not expose Powerwall to ambient temperatures above 60°C (140°F) or below -30°C (-22°F)." Compare that to the Yellow Caution that says "CATION: Avoid installing the Powerwall and Backup Gateway where it will be exposed to . . . ambient temperatures greater than 35 deg C." The former is an absolute requirement, enforceable at inspection; the latter is just a recommendation.

Cheers, Wayne

 

[ICE]

Wayne,
I have always been on the side of asking for the recommended items. Requirements morph into recommendations. Too many letters in that word to summarily ignore it. Truth be told, I have recommendations of my own.