If you agreed to a 50 amp circuit designed to charge your car then that is what you should have received. You have wire installed for a 40 amp circuit. The person needs to fix it in that case. I would ask the electrician if 8 gauge wire on a 50 amp breaker conforms to the Electrical code. Of course he/she might simply replace the breaker with a 40 amp breaker.
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Hot outlet reducing charging speed
- Thread starter Jpjpjp
- Start date
What amperage are you charging at where it gets so warm? Isn’t it limited to 32amps for model 3 now? Just read about this limiting....
voip-ninja
Give me some sugar baby
LR version of Model 3 has no problem charging all the way up to 48 amps. This person isn't encountering "limiting" of the car's charger, he has an improper outlet installation.
Any reason to use 8awg on a 30amp circuit? I know Tesla recommends 10awg for up to 100 ft, but I was going to ask for 8awg until reading their recommendation of 10.
https://www.tesla.com/sites/default.../NEMA_10-30_installation_guide_NA_US_2017.pdf
https://www.tesla.com/sites/default.../NEMA_14-30_installation_guide_NA_US_2017.pdf
https://www.tesla.com/sites/default.../NEMA_10-30_installation_guide_NA_US_2017.pdf
https://www.tesla.com/sites/default.../NEMA_14-30_installation_guide_NA_US_2017.pdf
voip-ninja
Give me some sugar baby
Why would it be a problem going to a larger wire? What's the concern? The only issue would be if you go to a wire gauge that isn't compatible with the outlet hardware or other things you would be using.
Butane
Member
Assuming you're in a garage where the ambient temperature can exceed 86 degF, then you can point your electrician to NEC Table 310.15(B)(2)(a) [PDF], and tell him that he's not derating the conductors properly.
Also, as others have said, the industrial grade NEMA 14-50 outlet is actually important. Tesla doesn't seem to recommend specific part numbers now, but these are the ones they used to and the only two semi common ones. Hubbell part HBL9450A or Cooper part 5754N. General rule, if the outlet cost less than $50, it's probably the wrong one.
Edit: Reviewing FlasherZ's excellent FAQ points out that NEC article 334.80 requires electricians to size NM cable by the 60degC column for installation, but allows use of the 90degC column for derating values. This makes the above temperature argument moot. 8AWG cable is only good for 40A per this article. Make sure you get what you paid for, no matter the actual current draw of the charger. Just tell the electrician you may park an RV in your garage one day.
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This would be correct, that and voltage drop is over a long (100+ ft) run, which is fairly uncommon. I used #10 for my install precisely because of cost. Also, my total run was like 35 ft (for 30 amp breaker install).
voip-ninja
Give me some sugar baby
There is no reason to use a larger conductor that what the electrical code calls for.
Some people oversize the wire if it's in a difficult installation location since it's easier to install new termination hardware like breakers, outlets, chargers, than to re-run the cable.
Limiting the charge current in your car's setting may temporarily reduce the overheating until you can get your electrician to fix the installation.
I have 6 AWG wire but unfortunately could not convince my electrician to use the industrial grade outlet. When he just showed up with the $10 receptacle I didn't have the time or energy to argue. I hate "professionals" who use the "you don't need it" argument.
I'm an electrical engineer. There's a reason the expensive parts are more - expensive.
I have 6 AWG wire but unfortunately could not convince my electrician to use the industrial grade outlet. When he just showed up with the $10 receptacle I didn't have the time or energy to argue. I hate "professionals" who use the "you don't need it" argument.
I'm an electrical engineer. There's a reason the expensive parts are more - expensive.
I also try to think of future usage - if there's a possibility of wanting to charge additional EVs or EVs that can take more current then it might make sense to run larger wires now and then just replace the breaker and receptacle down the road. For shorter runs the cost of the wire is a pretty small portion of the total cost of install so it can make sense to go up in size initially.
I just installed my outlet on my own at my house.
I used about 35ft of 6/3 copper wire from Home Depot: Southwire 50 ft. 6/3 Stranded Romex SIMpull CU NM-B W/G Wire-63950032 - The Home Depot
I used a 2-pole 50A circuit breaker from Home Depot: Eaton BR 50 Amp 2 Pole Circuit Breaker-BR250 - The Home Depot
I used this outlet from Home Depot: Leviton 50 Amp Flush Mount Shallow Single Outlet, Black-R10-00279-S00 - The Home Depot
My Model 3 charges at 32A max on my level 2 home power. It does not go to 48A.
It draws much more current when at a SuperCharger.
I used about 35ft of 6/3 copper wire from Home Depot: Southwire 50 ft. 6/3 Stranded Romex SIMpull CU NM-B W/G Wire-63950032 - The Home Depot
I used a 2-pole 50A circuit breaker from Home Depot: Eaton BR 50 Amp 2 Pole Circuit Breaker-BR250 - The Home Depot
I used this outlet from Home Depot: Leviton 50 Amp Flush Mount Shallow Single Outlet, Black-R10-00279-S00 - The Home Depot
My Model 3 charges at 32A max on my level 2 home power. It does not go to 48A.
It draws much more current when at a SuperCharger.
Butane
Member
Congrats! You may consider replacing the Leviton outlet with an industrial grade one, per Tesla's requirements. Common outlets that meet that spec are the Hubbell HBL9450A and Cooper 5754N. Do this especially if you plan on unplugging the mobile charging adapter repeatedly, as a big difference in the outlets are the number of mating cycles they're rated for.
Glamisduner
Active Member
Ok I have questions now.
I just changed out some 10-30 outlets to Nema 14-30's (they have 4 prongs). Re-wired my dryer and replaced the 20 amp breaker that was there with a 30 amp breaker (seemed to me they had used the wrong one). For some reason run length didn't occur to me, I thought it wasn't as relevant in 240v applications for some reason, I guess I was just not thinking about it. While I can't measure the run exactly I would guesstimate it pretty close to 100 feet or less (maybe closer to 80) (will get some measurements when I get home to get a better idea).
Should I change the breaker back to a 20 amp? I guess my dryer does not pull much since it wasn't tripping the 20 amp, but I was doing these changes in case I am not able to install a 14-50 or a wall charger before I get my model 3. I'm currently using the outlet to also charge my Chevy volt @ 16amps.
The wiring is old copper / paper romex from the 60's.
As for the original question, I would think 8awg may be fine if the run is very short, but if it's a long run you would want 6awg.
I'm actually tempted to run some 6awg myself but I'm afraid. I need to run it up through my crawl space, so does it need to be inside some sort of conduit?
I just changed out some 10-30 outlets to Nema 14-30's (they have 4 prongs). Re-wired my dryer and replaced the 20 amp breaker that was there with a 30 amp breaker (seemed to me they had used the wrong one). For some reason run length didn't occur to me, I thought it wasn't as relevant in 240v applications for some reason, I guess I was just not thinking about it. While I can't measure the run exactly I would guesstimate it pretty close to 100 feet or less (maybe closer to 80) (will get some measurements when I get home to get a better idea).
Should I change the breaker back to a 20 amp? I guess my dryer does not pull much since it wasn't tripping the 20 amp, but I was doing these changes in case I am not able to install a 14-50 or a wall charger before I get my model 3. I'm currently using the outlet to also charge my Chevy volt @ 16amps.
The wiring is old copper / paper romex from the 60's.
As for the original question, I would think 8awg may be fine if the run is very short, but if it's a long run you would want 6awg.
I'm actually tempted to run some 6awg myself but I'm afraid. I need to run it up through my crawl space, so does it need to be inside some sort of conduit?
The mobile connector is limiting the current, not the Model 3. If you were to install a HPWC on a 60A circuit then you could charge at the full 48A.
Butane
Member
Run length for a given wire size is generally limited by the voltage drop across the line when under load. No more the 5% off nominal = 114V minimum, though I have not seen any electrician care about this in my area. Other things that can impact wire size are deratings due to number of conductors in a conduit (likely not a problem for you now) or maximum expected ambient temperature.
NM-B (Romex) is permissable in crawlspaces, assuming no local restrictions. If using conduit, you cannot use romex and must run individual THHN conductors.
Some other concerns: You swapped from an outlet without a neutral to one with a neutral. Devices hooked up to a 14-30 (or any 14 series) can expect to get 120V between a hot and the neutral conductor. Not having this available can cause catastrophic failures. Was there a 4th wire in the wall already, just not hooked up? If not, you really need to put the 10-30 back on.
The problem with breaker sizing is you need to assume the entire lenth of wire is up to code for 30A capacity. It is bad practice, but not generally against code to mix wire sizes (assuming splices are in boxes, etc...) on a run, as long as the breaker is sized to the minimum capacity of wire in the circuit. If you can't inspect the whole run, I would be very hesitant to move to 30A breakers.
30A outlets on a 20A breaker are a code violation though, as 20A outlets exist. Only exception I'm aware of is 50A outlets on a 40A breaker.
Glamisduner
Active Member
Yea, I'm always hesitant to just change to a larger breaker, however it was a 30A outlet with a 20amp breaker, not sure this would have ever been to code in the last 50 years?.... I thought it should be a 30amp breaker as the wire is 10/3 and I was replacing a 10-3 outlet. When we had the panel redone, maybe the guy put in the wrong one, or maybe thats what was there before so he just coppied it.... I imagine it's one continuous run as there is no reason for it to not be, but can't see much in the crawl space due to ducting, insulation etc. Yea the ground wire (4th wire) was in the cable, just not connected to anything, or run into the box (had to pull off some drywall to find it).
Sounds like I should be good to go, so long as the run isn't over 100 feet? It's from one side of the house to the other but we don't have a large home, 1400 sqft...
One more thing, I'm reading that in a crawl space (non permanent stairs or ladder) you can simply run romex, but it has to be 6' away from the entrance hole. This would not be possible as you can't really get to 6 feet away as you can only crawl down the center. Guess that means I'm stuck with THHN and a separate conduit (we have a metal one already but it's for the solar Inverters that backfeed into the panel).
I want to save some cash, but I also like everything to be to code and not burn my house down.
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I won't be removing it until I move, so maybe never. Thanks for looking out
My hardware stays cool.
Edit: Also, what is "industrial". Tesla does not specify the brands you suggest or any brand for that matter. In fact, the bond between the pins of my adapter cable and the sockets of the receptacle is very strong.
If you have actual information/specifications for what is "industrial", please do share. Otherwise, I am taking your reply with a grain of salt.
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I will be extremely annoyed if he asks for more money. I called a few electricians for quotes and told them I wanted a 14-50 installed for my EV. This guy says he’s done a bunch before and gives me the lowest quote of the bunch. I literally picked him BECAUSE of the lowest quote. If he comes back and tells me he wants to charge me more, it pretty much feels like a bait and switch because depending on how much extra, i could’ve went with someone else instead.
I guess i have no one else to blame but myself for being a cheapskate
32amps. It drops to 16amps when it senses it’s getting too hot. I went to my car to check on it when I kept seeing it drop to 16amps on my app. That’s when I saw the message in the car that I attached on the original post
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