Lithium-ion battery fires do not depend upon external oxygen to burn. The materials inside the cell provide both fuel and oxidizer.
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Powerwall install location
- Thread starter esquid2
- Start date
I think of the drywall as buying you time to flee the house... Hopefully the multiple smoke/heat alarms go off early. A fire from a Powerwall in a crawl space or open basement could damage a great deal of the house quickly. I suspect that is why code specifies drywall. Personally, I would think about thicker layers than code to buy everyone time.
One of our first houses had a fuel oil tank in the basement with a floor to ceiling brick wall enclosure, and a window to the outside, which always struck me as a good way to buy time in the event of a fire.
For anyone considering enclosing a Powerwall (nearly had a Freudian slip there and wrote Firewall
), I recommend looking at some of the online videos of battery fires. These can be hot intense fires, and I would consider upping the barriers with multiple heat sensors and smoke detectors.
As with the video @sunwarriors posted, I don't think I would want to be anywhere near a battery fire, even wearing nomex.
And no, I am not a fireman, nor do I play one on tv...
All the best,
BG
One of our first houses had a fuel oil tank in the basement with a floor to ceiling brick wall enclosure, and a window to the outside, which always struck me as a good way to buy time in the event of a fire.
For anyone considering enclosing a Powerwall (nearly had a Freudian slip there and wrote Firewall
), I recommend looking at some of the online videos of battery fires. These can be hot intense fires, and I would consider upping the barriers with multiple heat sensors and smoke detectors.As with the video @sunwarriors posted, I don't think I would want to be anywhere near a battery fire, even wearing nomex.
And no, I am not a fireman, nor do I play one on tv...
All the best,
BG
Technically, since it is UL listed for stacking it is a single unit in the eyes of the code. Agree most AHJs consider all electrical equipment to require access while energized. Transformers used to be an exception 10-20 years ago, but not today in most places.
I also found the code citation for that:
2017 NEC 706.10(C) or 2020 NEC 706.20.C.2 Specifically allows working space between components within the system in accordance with the manufacturer's recommendations and listing.
the installation instructions specify the clearance needed on all sides. It's mostly for thermal management ventilation.
I would give it much more space, as there are replaceable parts that are only accessed from either side, like 3 feet either side. The tech needs to be able to get to the sides as well. You don't want a tech having to take the Powerwall off the wall just to service something small.
Thanks @miimura and @BGbreeder for replies! FWIW @miimura the install manual available from Telsa (page 41) gives very small clearances:
Nothing about front though. Thanks @BGbreeder, I didn't know how common such servicing is but assumed most of that would be done via the front taking off a front panel and that 12" on each side would likely be sufficient. Wouldn't be too hard to give more side clearance.
Main thing I really don't know is how much front clearance is required and whether a standard (32"?) fire door in front of the Powerwall would be adequate for whatever clearance is required. Either way, the ventilation definitely seems like an issue and not something I see specified at all in the installation manual. Quite the opposite it seems like it expects to be installed somewhere open with air flow, rather than somewhere fire sealed like the AHJ is requesting.
| Minimum clearance from left side (air intake) | 2 in (50 mm) |
| Minimum clearance from right side (air exhaust) | 6 in (150 mm) |
| Minimum clearance above single Powerwall | 2 in (50 mm) |
| Minimum clearance above side-by-side Powerwalls | 12 in (300 mm) |
| Minimum clearance between side-by-side Powerwalls | 10 in (250 mm) |
Nothing about front though. Thanks @BGbreeder, I didn't know how common such servicing is but assumed most of that would be done via the front taking off a front panel and that 12" on each side would likely be sufficient. Wouldn't be too hard to give more side clearance.
Main thing I really don't know is how much front clearance is required and whether a standard (32"?) fire door in front of the Powerwall would be adequate for whatever clearance is required. Either way, the ventilation definitely seems like an issue and not something I see specified at all in the installation manual. Quite the opposite it seems like it expects to be installed somewhere open with air flow, rather than somewhere fire sealed like the AHJ is requesting.
I think that you are right to be concerned about ventilation. Each Powerwall throws off 100W or so in idle, so heat will build up quickly in a small space. BUT, you want to vent this to the outside directly, so that any flames go outside rather than across your basement, which is what the AHJ is concerned about, right?
Someone with more experience with NEC should comment, but generally the set backs are on the order of 36" in front. Here, each Powerwall has to be 36" away from its neighbor.
All the best,
BG
