Charge using house air conditioner circuit with a switch?

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PaulK

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#1
We have a 30 amp circuit feeding a shut-off box connected to our compressor at the side of our house next to our garage wall. I'm thinking of hiring an electrician and asking them to add a 30amp DPDT switch to toggle between the ac compressor and a hardwired wall charger (set to 24amps).

Has anyone seen this done, or know any reason it may not meet code? I'd like to have some more knowledge on the idea before presenting it to an installer.

Thanks,
Paul
 
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Boyds, MD
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#2
I wish I could have found some sort of automated relay box that could share a circuit. We have a 50A aux heat circuit on my zone 1 geothermal heat pump, which gets used maybe 10 times a year when it is really cold. It is very close to the garage. So that would have been the ideal place to connect. My panel is on the opposite side of the house and installation quotes were $2,000+ for a new 50A circuit to be brought into the garage.

My dryer connection is in the mudroom adjacent to the garage, so I am purchasing a fully automated Dryer Buddy, with NEMA 10-30 plugs on it because this was the easiest thing for me to do. It gives priority to the dryer plug, so when the dryer runs it gets the circuit and when the dryer is off the Tesla mobile connector gets the power. It is schedule to arrive tomorrow.
 

PaulK

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#3
That's a good idea. I wonder if I install a dryer buddy and connect the Air Conditioner compressor where the dryer goes. Then the air conditioner would still run when called, interrupting the charging.

The two possible issues I can see would be 1) is putting a 30 amp plug on the air conditioner compressor feed ok... and 2) will the tesla charger mind being interrupted every 20-30 minutes when the house AC needs to run in summer.

Let me know how the install goes.

Thank you,

Paul
 
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#4
It isn't really an install. The dryer buddy requires no electrician. It's just like an extension cord. I unplugged the dryer from the wall plug the dryer buddy in. Then plug the dryer into the primary "outlet" on the dryer buddy, and plug the Tesla mobile connector into the secondary plug. I ordered the secondary plug to be on the end of a 35 foot extension cord. It worked perfectly.

The only weirdness is that if charging is interrupted (by someone using the dryer) I'm not sure if the car restarts charging. I gave it 10 minutes and it didn't start charging again. I did receive a notification on my phone that charging was interrupted, and you can restart the charging from the Tesla app. Seems weird that it doesn't just restart when the power comes back on. As a 1 day owner I strongly recommend this as a very quick and easy solution.
 

PaulK

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#5
Got it, thanks for the info about the charging not restarting. This would be an issue. Let me know what you learn.

For my "home A/C" situation, I would need to have a 30-amp outlet installed and a plug added to the A/C compressor. If that's allowed.

Paul
 

Sandy

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#6
Got it, thanks for the info about the charging not restarting. This would be an issue. Let me know what you learn.

For my "home A/C" situation, I would need to have a 30-amp outlet installed and a plug added to the A/C compressor. If that's allowed.

Paul
I like your idea of a double pole double throw disconnect. I considered one for the stove circuit but eventually did a service/panel upgrade so I can run the WC at 48 amps when required.
 
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#7
We are hoping to repurpose an unused cooktop circuit (40A) for the charger in order to avoid replacing the panel, which has no further room to add high amperage breakers. There is room for a 20A breaker in there, but I'd like to do better than charging at 10-15 mph if I can. Highly recommend considering this if you have a gas cooktop (or dryer).
 
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#8
Hello - I actually just emailed my electrician about getting permit to install DPDT with my dryer circuit. Found one rated at 30amp for about $100. What is the latest with your plans on the AC unit? I am concerned with consistently killing power and restarting of the WC. We probably would flip it on and off 3 times a week. Of course a smart sensing system would be more ideal but I am wondering if there is something that is even timer run --- (i dont have experience yet with a tesla, but) would it work if I plugged it in when I parked assuming WC is powered off and then power comes on at say 2AM and cuts off again at 8AM?
 

PaulK

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North Bay, CA
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#9
My electrician said the DPDT 30amp switch should pass inspection if needed. I found one through Walmart for only $48: https://www.walmart.com/ip/Leviton-...le-Pole-AC-Quiet-Switch-NAFTA-White/125724290

Says 3 in stock now.

This is for a house where I will only occasionally charge. If it’s hot and we need the AC, then I will just forego charging. Both the house AC and the charger will be hard wired, running through this switch.

I also like CrickTic’s suggestion. The kitchen shares a wall with the garage, but this house has a natural gas oven so they only wired a 120 outlet behind it. The laundry room is upstairs so in this case the only “easy” solution I see is tapping into this existing 30 amp 240 line feeding the AC compressor in the side yard (sharing a wall with the garage).

Paul
 
Last edited:
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#10
That switch might work, I don't know enough about code and wiring of that switch. But remember you are going L1-L2 for the 240V and not Line-Ground... This is something like I was thinking of, https://www.homedepot.com/p/GE-30-A...-Double-Throw-Safety-Switch-TC35321/202978650

But the more I have been thinking about it, I may just convert a single 120V outlet on a 20-amp CB to a 240V 20-AMP CB since I have the room in my panel and can just change the outlet out to Nema 6-20 which gives 15mph charging on the M3. I am waiting to see if electrician thinks I can get approval for that. would be simple and with my commute I can live with that
 
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#11
I don’t think you can support the same amperage if you do that. You’re effectively doubling the power being delivered over that wire. Your electrician will know for sure though.
 
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#12
It should be no problem to convert the outlet to a 6-20 240v. The amperage is still 20A. You are just going from one hot wire and a neutral to two hot wires. The white wire that is now hot must be marked as a hot wire on both ends with coding tape.