Installing a Nema 14-50 on a 30 Amp Breaker

[RaeW]

Sure, it CAN work fine. But you can't tell us that there isn't a possibility that the perfect storm of the car forgetting the setting and a faulty breaker couldn't occur and cause a fire. Doesn't seem like it's worth saving a few bucks. Anyway, the main thing is that it would be irresponsible to recommend it to newbies asking for guidance here, even if it works for you.

I don't recommend anything. Perhaps you did not see my post to whoster69 who raised this issue to begin with. Here it is as previously posted:

I did this exact same thing, but there are cautions.

My electric dryer outlet, while dedicated, is fed from the panel to a junction box in the basement rafters. This is because the genius electrician who did original construction knew I had a gas dryer and tried to save a few bucks by running a line in the basement only (dryer is above box on first floor). I made him complete the job before we moved in. Several years ago I disconnected the dryer outlet at the junction box and ran the line to the garage (luckily the electrician had used a deep junction box). I have been using this 30 amp circuit for charging my MS (at 24 amps) since 2015.

NOTE THE REQUIREMENTS:
Check your local building code.
You must use the proper gauge wire for the distance (your dryer line may or may not meet this requirement).
You must use the proper outlet (don't use the dryer outlet).
You can only charge at 80% of breaker rating (24 amps on a 30 amp breaker).

 

[eladts]

I have a 240 v circuit fused for 20 amps. I use a NEMA 6-20 adapter that does not limit the amps rate. I have the car set to limit the amps rate to 16 amps (80% of the circuit breaker rating) and have had no trouble charging. I get 13 miles/hour and charge every night to 80% capacity. The only other place that I charge is at superchargers when I travel. The 16 amp rate restriction does not affect charging at superchargers and I believe that it is location dependent so if I charged with the same setup at a different location I would have to reenter the rate restriction.

I assume that your outlet is NEMA 6-30. If Tesla sells a NEMA 6-30 adaptor, that would be ideal. If they do not so you have to use a third party device, you need to limit the amps rate in the car to 24 amps (80% of the 30 amp circuit breaker rating).

Why not do it the safe way and just buy the Tesla NEMA 6-20 adapter? The official adapter will automatically limit the current to 16A. It costs only $35, a tiny price to pay for the safety of you and your family.

 

[Vines]

I too have done things that aren't code complaint in my own home. I rebuilt some walls with 2x4 rather than 2x6 framing.
However imagine the case when someone ran some #18 wire to a location and you really wanted to re-use that wire for an standard duplex outlet. You really only want to put one small light there, and it only draws like 2 amps. Would you go ahead and wire up that outlet with 18 gauge wire and put a sticker on the cover plate that says "2A only"?

Not trying to jump all over you and I agree if nothing changes it will likely be fine 999 times out of 1000 or even better. It is clear that you have not overloaded this circuit to this point, and that to this point your cars programming has maintained the 24A limit on this circuit. Hopefully this 30A breaker isn't in a zinsco panel, as its the last line of defense if something changes!

Then 1 in 1000 times someone in your situation will get sick and never remember to pass along that info about that special non code compliant outlet they installed. Then the real estate agent goes to plug in her Tesla...

While I am inventing an edge case to represent that 1 in 1000 chance of things going wrong, codes and standards protect from these edge cases without having to rely on one persons current state of mind, or tribal knowledge that may or may not get passed on to the next generation.

Anyway, its up to you. Yours wouldn't be the first non compliant wiring in a home, nor the last.

 

[Whoster69]

We have decided to put in a Nema 14-50 (sorry about the earlier error, for some reason my brain wants to reverse this to 15-40), 6 gauge wire and a 50 amp breaker.

 

[ben1628]

I just don't understand why someone spent at least $50K on a Tesla can go cheap in setting up a home charging system. How much does it costs to get a professional to do it if you are not comfortable?

Just wire 6 gauge wire, put a 14-50 and a 50 Amp circuit breaker, and YOU are done, and now you can enjoy the car and get a good night sleep.

 

[RaeW]

We have decided to put in a Nema 14-50 (sorry about the earlier error, for some reason my brain wants to reverse this to 15-40), 6 gauge wire and a 50 amp breaker.

This of course assumes you have code panel capacity to add a 50 amp breaker? In my case I did not.

 

[RaeW]

I too have done things that aren't code complaint in my own home. I rebuilt some walls with 2x4 rather than 2x6 framing.
However imagine the case when someone ran some #18 wire to a location and you really wanted to re-use that wire for an standard duplex outlet. You really only want to put one small light there, and it only draws like 2 amps. Would you go ahead and wire up that outlet with 18 gauge wire and put a sticker on the cover plate that says "2A only"?

Not trying to jump all over you and I agree if nothing changes it will likely be fine 999 times out of 1000 or even better. It is clear that you have not overloaded this circuit to this point, and that to this point your cars programming has maintained the 24A limit on this circuit. Hopefully this 30A breaker isn't in a zinsco panel, as its the last line of defense if something changes!

Then 1 in 1000 times someone in your situation will get sick and never remember to pass along that info about that special non code compliant outlet they installed. Then the real estate agent goes to plug in her Tesla...

While I am inventing an edge case to represent that 1 in 1000 chance of things going wrong, codes and standards protect from these edge cases without having to rely on one persons current state of mind, or tribal knowledge that may or may not get passed on to the next generation.

Anyway, its up to you. Yours wouldn't be the first non compliant wiring in a home, nor the last.

I hear your Nth degree concern. Perhaps I will look into changing the 14-50 to a 14-30 (dryer socket that I have) and getting a 14-30 adapter from TESLA. As I tested the line and the 30 amp panel breaker trips at 28, I don' think this will make me feel any safer. It's just semantics. In my view a 30 amp line with a 30 amp breaker that trips at 28 with the car set to 24 and, if it fails, will revert to 40 on a breaker that trips at 28 is about as safe as one can be.

 

[TexasEV]

This of course assumes you have code panel capacity to add a 50 amp breaker? In my case I did not.

Then install the circuit you have capacity for, meaning the matching breaker, wire size, and outlet. Buy the UMC adapter for that outlet. Don’t be stubborn and insist your kludge setup is just as safe. It isn’t. Even if you don’t care that a confluence of rare events could cause a fire, the rest of us do because the headline will say “Tesla charging causes fire”, not “improperly wired garage causes fire”.

 

[RaeW]

Then install the circuit you have capacity for, meaning the matching breaker, wire size, and outlet. Buy the UMC adapter for that outlet. Don’t be stubborn and insist your kludge setup is just as safe. It isn’t. Even if you don’t care that a confluence of rare events could cause a fire, the rest of us do because the headline will say “Tesla charging causes fire”, not “improperly wired garage causes fire”.

Wow! You have convinced me! I have ordered the 14-30 adapter from TESLA. Now I can use my disconnected dryer socket! Anyone that has posted 7,292 messages must know what they are talking about!

 

[timk225]

I have 85 feet of 6/3 wire running from a 50 amp breaker to the 14-50 outlet in my driveway for daily charging, it has been in use since October. I also have about 60 feet of 12/2 wire running from a 20 amp breaker to a 6-20 outlet, it handled my charging needs until the driveway was built. I also have a 15 foot long 14-50 Camco extension cord, which I used in conjunction with my oven's 14-50 outlet, to charge the car until the 6-20 was put in. Setting up and taking down that extension cord every time I had to charge the car got old fast.

When the 14-50 begins to charge and is still under 10 amps or so, it has 241 volts, and once it ramps up to the full 32 amps, voltage drops to 235 / 236.

 

[ohmman]

mod note: 15-40 in title amended to 14-50.

 

[LCR1]

You can’t put NEMA 14-50 receptacles on a 30A circuits! Not only that would be a code violation, but it would cause immediate problems when charging a Tesla! Here is why.
The type of the NEMA plug (adapter) you use with the UMC tells your car what’s the highest current the car is allowed to draw. If you use the 14-50 adapter, the car will assume you have a 50A rated circuit and will charge at a higher current than it’s supposed to! At best this will trip your circuit breaker, at worst, this can cause fire!

DO NOT DO IT!!!

You can still manually adjust the amps pulled via the car.

 

[Goodtohave]

You can still manually adjust the amps pulled via the car.

Again why would you not buy a $35 adapter from Tesla and be 100% safe at the correct draw?

We also have to reset the car sometimes when it doesn’t work...the car may make a mistake and draw too much, the adapter won’t.

I think it’s great that Tesla offers all the adapters, such an inexpensive easy solution compared to what it cost me to set up my EVSE for my Leaf years ago

 

[G78M3]

I hear your Nth degree concern. Perhaps I will look into changing the 14-50 to a 14-30 (dryer socket that I have) and getting a 14-30 adapter from TESLA. As I tested the line and the 30 amp panel breaker trips at 28, I don' think this will make me feel any safer. It's just semantics. In my view a 30 amp line with a 30 amp breaker that trips at 28 with the car set to 24 and, if it fails, will revert to 40 on a breaker that trips at 28 is about as safe as one can be.

I agree that your setup is as safe as one can be, as long as you are the one using it.
But *sugar* happens in life, and today you are here but tomorrow you may not; someone else moves in and then it’s not the safest setup anymore. Not even close.

 

[LCR1]

Again why would you not buy a $35 adapter from Tesla and be 100% safe at the correct draw?

We also have to reset the car sometimes when it doesn’t work...the car may make a mistake and draw too much, the adapter won’t.

I think it’s great that Tesla offers all the adapters, such an inexpensive easy solution compared to what it cost me to set up my EVSE for my Leaf years ago

Because I wasn't talking to you, which is why I didn't quote you.

 

[sublime8365]

Not looking to hijack this thread, but my situation is very similar (in fact I signed up for this forum to ask similar questions here)...

I had an electrician come to install a 14-50 outlet for charging in my garage with the intent to install a 50 amp breaker, however the guy that came to install looked at the 14-50 mobile adapter and there was something written on it that said 30 amp (can't remember the exact print and I'm not at home to look now) and so he insisted to me that a 30 amp breaker needed to be installed (even though I pulled up the installation PDF for him from the Tesla site). What he did was install the 14-50 outlet and the correct gauge wire that can handle a 50 amp breaker, but used a 30 amp breaker in the box (so presumably my dangers are more limited than the OP here but the heat in a 30 amp breaker getting 32 amps through is a concern). I can confirm that my Tesla phone app has said it's pulling the full 32 amps and the breaker never tripped during 2 charging cycles (about 4.5 hours each). It did get hot but not nearly hot enough to start a fire (not exactly something that puts my mind at ease but I wanted to provide that anecdotal information). I was going to change the breaker out myself but I'll be reaching back out to the electrician mostly to ensure that this guy isn't making this mistake on future customers who might not catch the mistake like I did.

Questions I'm hoping someone can answer for me:

• After 2 charging cycles, is there any chance that there's any damage/concern I should have on my battery or anything problematic with my car? I've noticed after the 2nd charge that my regenerative breaking has been limited but the temp has been dropping into the 40's here in Texas so I am hoping that these two issues are unrelated
• If I have the standard range plus model 3, should I be using a 40 or 50 amp breaker? The 14-50 installation guide on the Tesla site says 50 but the onboard charging information page says 40 (see links below)

This shows 40 amp
Onboard Charger

This shows 50 amp
https://www.tesla.com/sites/default.../NEMA_14-50_installation_guide_NA_US_2017.pdf

 

[LCR1]

Not looking to hijack this thread, but my situation is very similar (in fact I signed up for this forum to ask similar questions here)...

I had an electrician come to install a 14-50 outlet for charging in my garage with the intent to install a 50 amp breaker, however the guy that came to install looked at the 14-50 mobile adapter and there was something written on it that said 30 amp (can't remember the exact print and I'm not at home to look now) and so he insisted to me that a 30 amp breaker needed to be installed (even though I pulled up the installation PDF for him from the Tesla site). What he did was install the 14-50 outlet and the correct gauge wire that can handle a 50 amp breaker, but used a 30 amp breaker in the box (so presumably my dangers are more limited than the OP here but the heat in a 30 amp breaker getting 32 amps through is a concern). I can confirm that my Tesla phone app has said it's pulling the full 32 amps and the breaker never tripped during 2 charging cycles (about 4.5 hours each). It did get hot but not nearly hot enough to start a fire (not exactly something that puts my mind at ease but I wanted to provide that anecdotal information). I was going to change the breaker out myself but I'll be reaching back out to the electrician mostly to ensure that this guy isn't making this mistake on future customers who might not catch the mistake like I did.

Questions I'm hoping someone can answer for me:

• After 2 charging cycles, is there any chance that there's any damage/concern I should have on my battery or anything problematic with my car? I've noticed after the 2nd charge that my regenerative breaking has been limited but the temp has been dropping into the 40's here in Texas so I am hoping that these two issues are unrelated
• If I have the standard range plus model 3, should I be using a 40 or 50 amp breaker? The 14-50 installation guide on the Tesla site says 50 but the onboard charging information page says 40 (see links below)

This shows 40 amp
Onboard Charger

This shows 50 amp
https://www.tesla.com/sites/default.../NEMA_14-50_installation_guide_NA_US_2017.pdf

Change out the breaker and tell the electrician they're retarded. You ordered 50amp setup and they should have installed a 50amp setup. Who's to say you won't plug in a welder or something else that actually requires a 50amp breaker. On a 30amp breaker you're only supposed to be charging at 24amps. 30 x 0.8 = 24.

• You're charging at 32 amps has nothing to do with reduced regen and everything to do with the cold weather.
• You should be using a 50amp breaker because you have a 50amp outlet with 50 amp wiring. The plug in the tesla cord will automatically limit you to the 32amp. No reason to have 50amp outlet and wiring and put in a 40amp breaker, again the car will limit everything on it's own.

 

[davewill]

Not looking to hijack this thread, but my situation is very similar (in fact I signed up for this forum to ask similar questions here)...

I had an electrician come to install a 14-50 outlet for charging in my garage with the intent to install a 50 amp breaker, however the guy that came to install looked at the 14-50 mobile adapter and there was something written on it that said 30 amp (can't remember the exact print and I'm not at home to look now) and so he insisted to me that a 30 amp breaker needed to be installed (even though I pulled up the installation PDF for him from the Tesla site). What he did was install the 14-50 outlet and the correct gauge wire that can handle a 50 amp breaker, but used a 30 amp breaker in the box (so presumably my dangers are more limited than the OP here but the heat in a 30 amp breaker getting 32 amps through is a concern). I can confirm that my Tesla phone app has said it's pulling the full 32 amps and the breaker never tripped during 2 charging cycles (about 4.5 hours each). It did get hot but not nearly hot enough to start a fire (not exactly something that puts my mind at ease but I wanted to provide that anecdotal information). I was going to change the breaker out myself but I'll be reaching back out to the electrician mostly to ensure that this guy isn't making this mistake on future customers who might not catch the mistake like I did.

Questions I'm hoping someone can answer for me:

• After 2 charging cycles, is there any chance that there's any damage/concern I should have on my battery or anything problematic with my car? I've noticed after the 2nd charge that my regenerative breaking has been limited but the temp has been dropping into the 40's here in Texas so I am hoping that these two issues are unrelated
• If I have the standard range plus model 3, should I be using a 40 or 50 amp breaker? The 14-50 installation guide on the Tesla site says 50 but the onboard charging information page says 40 (see links below)

This shows 40 amp
Onboard Charger

This shows 50 amp
https://www.tesla.com/sites/default.../NEMA_14-50_installation_guide_NA_US_2017.pdf

You can use either a 40a or 50a circuit successfully with the mobile connector. 50a is preferred since you have the capacity and the wiring is done correctly for that. For some bizarre reason, Tesla printed "30a" on the 14-50 adapter itself, however the setup draws 32a by design. You need to have that electrician change the breaker to 50a. Have him call Tesla if that's what it takes to convince him. A 30a breaker will not cut it and you shouldn't use the plug until it's fixed (or a least turn the amperage in the car down to 24 until it's changed).

 

[M3BlueGeorgia]

I hear your Nth degree concern. Perhaps I will look into changing the 14-50 to a 14-30 (dryer socket that I have) and getting a 14-30 adapter from TESLA. As I tested the line and the 30 amp panel breaker trips at 28, I don' think this will make me feel any safer. It's just semantics. In my view a 30 amp line with a 30 amp breaker that trips at 28 with the car set to 24 and, if it fails, will revert to 40 on a breaker that trips at 28 is about as safe as one can be.

The car won't draw more than 24A on a 30A circuit ... because one should never draw more than 80% continuous and the car knows the rules.

So you'll be fine.

 

[LCR1]

The car won't draw more than 24A on a 30A circuit ... because one should never draw more than 80% continuous and the car knows the rules.

So you'll be fine.

The car has no way of knowing what size breaker it's plugged into, it most certainly will pull more than 24A if you use a 14-50 plug