Hi all
I am having issues with a 6-50 Adapter used on Tesla Mobile connector. I have a 40 Amp breaker at home and when I connect Mobile connector with 6-50 adapter to outlet, mobile connector blinks orange and car shows alert something like power is reduced. I did some research and Tesla website recommends 50 amp circuit breaker for a 6-50 adapter, are these power issues because of 40A instead of 50Amp ?
I am going to assume since you are posting in the Model 3 forum that you have a UMC Gen 2. The UMC Gen 2 as others have stated will only draw a max of 32 amps so it is completely fine on a 40a circuit. If for any reason you had a UMC Gen 1 which can draw 40 amps then you MUST put it on a 50a circuit.
Make sure the UMC plug is fully inserted in the wall receptacle. Make sure the UMC adapter is firmly shoved into the UMC box itself. Then if the receptacle is getting too hot the UMC can detect that and scale back charging - so check if it is getting hot while charging. Also, if voltage drops too much once charging starts then that too can cause it to reduce charging speed - this likely indicates an electrical issue. I am worried you have a loose wire or something causing the receptacle to heat up too much.
You can manually turn down the charging draw on the charging screen in the car. Probably should set it to 32 amp draw for a 40 amp breaker. Better to change the breaker/wiring to a 50 amp to match the plug or change to a 30 amp plug so the car will draw 24 amps by default.
If you go all out (which I would recommend at home) and get the HPWC from Tesla (for $500) you can set the dial inside to 40 amps. It will also allow you to keep the mobile charger in the car at all times for when you are out on the road and quickly plug in the car at home.
Turning down the charging amperage on the charging screen is not code compliant. I would not rely on remembering that (or making sure the Tesla does not forget it after a software upgrade which others have reported) to keep from burning my house down. But with a UMC Gen 2 you don't need to turn it down. A 40a circuit with proper ampacity wire (which can be as small as 8awg) is totally fine. (but if installing new I would generally always install a 50a circuit with the right wire)
Yup that’s what I thought as well. I was using a EVSE which is 240V 32A max and I was getting 32AMP for charging. But when I switched to Tesla Mobile Connector that outlet didn’t work , so I wasn’t sure if it’s 6-50 Adapter issue or my outlet issue
So this same circuit and receptacle was fine at 32a before, but now the UMC has issues? It is possible that the UMC is detecting overheating of the receptacle or your car is detecting too much voltage drop. The old EVSE may just not have had those safety features and was not detecting a dangerous situation.
I thought you needed a 14-50 plug (4-prong)?? Either way, I'm not sure how the car could possibly know your on a 40 amp breaker vs. 50. Maybe your plug isn't wired right or you have a problem with the connection not being tight like the above person said.
Yeah, the car has no idea if you are on a 40a or a 50a breaker. All the UMC knows is that it has a 14-50 adapter head plugged into it but since the UMC is only good to 32a, it only charges at 32a, so it does not matter if it is a 40a or 50a circuit.
I ran 10 gauge wire ( 240V ) from my 50A circuit breaker to my Tesla Wall charger. The Tesla Wall charger limited my charge rate to 32A.
I removed my Tesla Wall charger and installed a 6-50 outlet and plugged in my Mobile Tesla cable. "All Green tesla letters".
I then plugged in my Mobile Connector to the car. After 5 min....the Mobile Tesla cable lights turned yellow.
I then went downstairs in my house to see if the breaker had an issue and as I felt the conduit ( by accident ) it was very very warm ( hot ) and vibrating ( humming ) to the touch.
Long story even longer.…….
After a tremendous amount of work and experimenting over 3 days ( charging at work only ) ....I changed my 65 feet of wire from 10 gauge to 6. NOW EVERYTHING works with no yellow lights...nor heat nor anything.
The Car didn't know anything...it just tried to pull everything it could and at some points during my 10 gauge wiring charging....and couldn't.
My voltage went down from 240V to 198V when the 10guage wires heated up my 3/4 conduit.
That's my experience.
My god. That was an unbelievably dangerous situation. As you point out, thank god it was in conduit. 10 gauge THHN wire in conduit is good to 35 amps (28 amps continuous). 10 gauge NM cable is only good to 30 amps (24a continuous). A 50a breaker was incredibly dangerous.
Ironically, 8 gauge in conduit is good to 50a, though 6 awg is even better. 6 awg you could do a 60a breaker if you had a Wall Connector instead of a 6-50.
@PatsFan : This is kind of an aside from your question (I don't know what might be the problem)...but...if you don't know already, personally I would double check what gauge wire is used for this circuit, as there is ambiguity - you have a 40A breaker with a 6-50 outlet on it. Having the lower amperage breaker is fine (and actually what I would prefer, if I knew I was never going to pull more than 32A on that circuit - it's safer), but I worry specifically that you have 8-gauge wire or something like that, with a 50A outlet. You need to have at least 6-gauge wire (for the main conductors) for this circuit. Otherwise the circuit shouldn't have a 50A outlet installed in the first place.
The UMC has the ability to check for excessive voltage drop (which would happen with insufficient wire thickness), and I believe it also can detect heating in the plug (due to a bad connection or some other problem), but others here who are experts can clarify those capabilities; I don't actually know. It's covered elsewhere in other threads.
Edit: TL;DR: My guess is your wire is undersized or something is wrong with your circuit. I would discontinue use until you figure out what it is. Do NOT put a 50A breaker on the circuit. It will just increase your
risk of fire, which may be
quite high already.
Yes, please double check the wire gauge just to be sure, however, 8 AWG is completely fine for a 40a circuit. 8 awg is even fine for a 50a circuit if it is THHN in conduit and the distances are not too far to have to worry about voltage drop. A 6-50 or 14-50 receptacle is totally legal on a 40a circuit as long as the intended load is not over 40a (or 32a continuous like an EVSE). Though again, I would generally never install a new 6-50 or 14-50 on a 40a circuit if I had the choice. Best to have a full 50a circuit.
I agree you need to figure out what is going on here immediately. This could be a fire risk. An extremely common issue (other than wrong wire size) is loose wire connections at the breaker, or the receptacle, or any intermediate connections. We have seen a couple of cases recently where wire was not stripped sufficiently before being shoved into the terminals on a receptacle and so the insulation was pinched and so the terminal was not making good contact with the wire. This caused the receptacle to overheat and melt.
10 gauge wire isn't meant to handle 32A continuous. Absolute minimum wire gauge is 8 gauge for a 32A continuous, but that should be paired with a 40 amp breaker. There's no actual plug for 40 amps, so it shouldn't be allowed period unless it was hooked to a Tesla HPWC. Be lucky you didn't burn something down.
8 gauge THHN wire in conduit is allowed to be used at its 75c rating which allows for 50a. So it is perfectly legal to use on a 50a circuit.
8 gauge NM cable (romex) is only allowed to be used at the 60c rating which limits you to a 40a circuit.
A 40a circuit is utterly and completely legal on a 6-50 or 14-50 receptacle as long as the intended load is not greater than 40a (32a continuous). So a UMC Gen 2 is totally fine. A UMC Gen 1 is NOT fine.
You got that right. I'm glad the wires were in conduit instead of any other solution. Lesson learned - NOT the hard way.
6 gauge is working just fine. Conduit is still cold after 30 min of charging. I'm actually thinking about going to 4 gauge in the future. Copper is expensive.
Why change to 4 gauge? If you are going to use a Wall Connector and charge at some higher rate this might make sense, but at 6 awg you are already oversized for a 50a breaker. If your run distance was not too long you could have used 8 AWG. Here is the chart I am getting all my data from: (but you have to know whether you are allowed to use the 60c or 75c column)
Ampacity Charts - CerroWire
Indeed. Everything is good now. No worries. Even with the Tesla Wall Charger @48A its all cool now.
Ahh, ok. So you did 6 awg and are using a Wall Connector, so does that mean you put in a 60a breaker then? A 60a breaker is required to charge at 48a.
I have 8 gauge wire for 40 Amp breaker
Ahh, just got down to this post. Ok- You need to check your connections at the receptacle (no insulation in the terminals and that they are tight), as well as at the breaker (or anywhere in between they are joined). The issue could also lie upstream in your panel our out to the utility transformer... If your car is getting low voltages then I would check them back in my panel with a multimeter while the car was drawing load.
8-gauge should be ok up to 32A. If you cut the current limit back in the car (can adjust it to 1A resolution and it will remember it...for a time anyway), does it help? And what voltage is measured by the car for each current setting including the flaky ones?
If the UMC 6-50 connector is from Tesla, and new, not sure what the problem would be, other than a socket issue.
Yeah, check the voltage on the Tesla display just as you plug it in and it starts charging (but has not ramped the amperage yet). Then watch the voltage drop as it fully ramps into charging (and perhaps say watch it for a while as the wires heat up - it could take a bit for the voltage to drop more due to some wiring issue). You will want to see voltage before the car cuts the charging speed down (as it does that to reduce voltage drop).
My bet is that you may have a loose connection to the 6-50 receptacle and it is getting hot causing the Tesla to ramp down charge rate. Either that or a loose connection elsewhere that is causing voltage drop which is causing the Tesla to ramp down charging rate.
