According to Article 2018 IRC M1307.3, appliances that could ignite vapors must be positioned at least 18 inches off the garage floor. Does this mean that all batteries, such as those from Tesla and Solaredge, must also be placed 18 inches above the ground? If we cannot place the batteries at this height, should a platform be added to achieve the required clearance?
Battery ground clearance ( inside garage)
- Thread starter MSI
- Start date
hbiss
EC, Westchester, New York NEC: 2014
- Location
- Hawthorne, New York NEC: 2014
- Occupation
- EC
EVs have no vapors to ignite. I'm sure the article refers to gas powered vehicles.
I would want to know how you would build a platform in a garage for a Tesla...
-Hal
I would want to know how you would build a platform in a garage for a Tesla...
-Hal
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
I think he is talking about Tesla PowerWall batteries.
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
No, generally speaking. These energy storage systems don't meet the definition of an ignition source in that code just by being electrical. If the ESS had an integral breaker or switch that would end up less than 18" from the floor then that could count, but ordinarily they don't. I've never run into this being a problem for energy storage installations.
ModbusMan
Senior Member
- Location
- Cleveland, OH
- Occupation
- Building Automation Engineer
Tire ramps. And hopefully some sort of "STOP NOW!!!!" mechanism so you don't go too far and drive off the ends of the ramps like a certain teenager did while in a rush to change the oil thirty-odd years ago :sweatdrop:
Fred B
Senior Member
- Location
- Upstate, NY
- Occupation
- Electrician
I've yet to see a Powerwall that would not fit at such an elevation. And yet to see a garage that didn't have head room that couldn't be stood up within so technically plenty of room for elevation of the Powerwall.
Under normal operation there would not be any sparking components for a Powerwall, but in the event of a fault or failure there is that potential so the minimum height would be adhered to.
Perhaps getting the dimensions of the proposed equipment might clear up this concern.
AFA a platform, what do you want to elevate to need a platform?
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
Powerwalls have provisions for floor mounting so it's partly a question if those provisions would be allowed in a garage, but also the discussion extends beyond that brand. Some ESS (such as Enphase) have dimensions that allow for two rows of equipment on a wall but the height of a typical garage wall may be a constraint to where you need to put the lower row within 18" of the floor. I've done exactly that many times.
The definition of ignition source in the mechanical code is:
"IGNITION SOURCE. A flame, spark or hot surface capable of igniting flammable vapors or fumes. Such sources include appliance burners,
burner ignitors and electrical switching devices."
To me that would apply to circuit breakers, switches, and receptacles where there might be a spark under normal operation, but not to wiring or equipment that would not normally be expected to produce such things. The point here is to prevent normally expected flame, spark or heat, from igniting vapors that might be in a garage (from a gasoline spill? I don't know what other low lying vapors they are specifically worried about.) I don't think the requirement should be extended to all items that could theoretically catch fire, or all items that are electrically energized, but which are not supposed to produce flame, spark or meaningful heat under normal operations. If a Powerwall catches fire that is its own problem; it's not a spark or flame that would otherwise be okay outside of the presence of vapors. So I strongly disagree with you on this statement, for the general case. Most lithium battery ESS have environmentally enclosed cell packs and would not necessarily produce external spark or flame for every internal fault. Some have integral switches or circuit breakers, so I would apply the rule to those components when present. But as long as the switch or circuit breaker is above 18" I would consider the requirement adhered to even if other parts of the ESS were below 18".
He was asking if elevating the equipment using a floor mount option would comply with the 18" requirement, if that applied. A platform would comply, in my opinion. (Probably rarely would it be the best option; with ESS that have wall mount options it would probably be easier to go that route. But you could do it if you wanted to.)
wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
Presumably that doesn't include solid state devices.
So I guess the question for something like Tesla Powerwall would be whether the enclosure has any vents or openings less than 18" above the bottom of the unit, and then if it does, whether it has any contactors or other electrical switching devices also less than 18" above the bottom unit.
I understand Powerwall 3 is designed to be flood resistant for up to 600 mm, so I expect that means it has no vents or openings less than 600 mm (~24") above the bottom. Not sure about Powerwall 2, although I expect that one has been discontinued?
Probably all a non-issue, but still worth confirming.
Cheers, Wayne
Elect117
Senior Member
- Location
- California
- Occupation
- Engineer E.E. P.E.
Does the powerwall suck in air from the bottom to cool the internals?
I don't know how accurate the image is below. I would mount it above 18" to be safe and move on. As Wayne mentioned, you wouldn't want the guys who come through cleaning the garage with water and soap soaking it either. That might not do anything with water "resistance" but long term it can wear away the paint and start rusting stuff.
I don't know how accurate the image is below. I would mount it above 18" to be safe and move on. As Wayne mentioned, you wouldn't want the guys who come through cleaning the garage with water and soap soaking it either. That might not do anything with water "resistance" but long term it can wear away the paint and start rusting stuff.
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
This is the language of the residential code requirement.
You guys are gonna have to convince me why the 18" would apply to vents when the language simply says the source of ignition.
Also even on ESS that have vents for active cooling there's typically going to be many layers of material between the airflow sections and the actual cells, i.e. still nothing normal that could ignite vapors.
You guys are gonna have to convince me why the 18" would apply to vents when the language simply says the source of ignition.
Also even on ESS that have vents for active cooling there's typically going to be many layers of material between the airflow sections and the actual cells, i.e. still nothing normal that could ignite vapors.
- Location
- Illinois
- Occupation
- retired electrician
So we can't have ICE cars in our garages...the normal operating temperature of the catalytic converter is 500 to 800 degrees F and the auto ignition temperature for gasoline is around 550 F. (note am calling the car an appliance here 
)
)rlqdot
Member
- Location
- St. Louis, MO - USA
- Occupation
- Professional Engineer (multiple states) - building design
oil-based paint, paint thinners, alcohol (even in windshield washer fluid if stored in large enough quantities), gasoline, etc. vapors are almost all heavier than air - that is where the 18 inches AFF comes from, the code is trying to prevent ignition sources from a zone where those vapors might be. if an air intake sucks up those flammable vapors / gasses, the moving air may dilute them adequately so that they are no longer flammable / explosive, but i wouldn't want to take that gamble in my garage. i know we can't change the way the Power Wall is manufactured, but it almost seems like it would be better if the fans were at the top but drew ventilating air IN at the top and drove it OUT at the bottom.
wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
Good question. I have a Powerwall 2, it sucks in air on the top of the left side and blows out air on the top of the right side. Powerwall 3 could be different, but there are claims of flood resistance to 2', so if there is an air intake low, I infer the air passage is sealed from the rest of the unit for at least the bottom 24".
Cheers, Wayne
wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
It doesn't, so you can ignore my comments about vents. So all we need to do is confirm that there are not contactors in the bottom 18" that are open to ambient atmosphere. Which is surely true, given how long the product has been on the market and that I've never heard of this possible issue before.
Cheers, Wayne
Elect117
Senior Member
- Location
- California
- Occupation
- Engineer E.E. P.E.
I don't know why my head went to parking garage. Like a high rise building. Though 511.3(A) covers that as non classified because of venting in garages.
Is it reasonable that someone might do work on a car in their own garage? Sure.
Is it reasonable that oils, fumes, soaps, detergents, etc. could be spilled? Sure.
Do I think impact protection is more important? Yes.
It isn't my garage or install. It could be safely installed on the floor. It could also be unsafe. I think that will depend more on the location it is in the garage and the user.
I have seen plenty of garages filled with clutter, kids throwing their bikes around, etc. that could be more of an issue than fumes.
Is it reasonable that someone might do work on a car in their own garage? Sure.
Is it reasonable that oils, fumes, soaps, detergents, etc. could be spilled? Sure.
Do I think impact protection is more important? Yes.
It isn't my garage or install. It could be safely installed on the floor. It could also be unsafe. I think that will depend more on the location it is in the garage and the user.
I have seen plenty of garages filled with clutter, kids throwing their bikes around, etc. that could be more of an issue than fumes.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
It's hydrogen, which is not a vapor. It's a very light gas that heads for the ceiling whenever it is released.
You're right, technically, it's not vapor
For lithium batteries, this requirement ( 18" off the ground)does not come from something the batteries are off-gassing; it comes from the environment they are in. All battery systems currently in production are an arc flash hazard. Garages store a multitude of things including chemicals, one of the most common chemicals to be stored in a garage is gas. As gas fumes are heavier than air it is one of the reasons the code requires things that may cause a spark to be at least 18” off of the floor.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems