The previous owner of our house had 2 40A circuits going to a dedicated garage junction box. Based on what other items I saw laying around, I think he was growing cannabis. This is in CO so it's legal to grow the sticky icky. I was jazzed to see 2 40A breakers on the panel and purchased a NEMA 14-50 plug so I can charge at the max 32A that the included charger can charge at. When I went to wire it up, I realized that it was not the 4 wire arrangement that is needed for a NEMA 14-50 but the standard 3 wire (black, white, ground). I have 2 questions: Is it possible that this is a 220v or can that only be achieved with 4 wires? Second question: if it is only 110v what plug should I put in to allow for the fastest charging?
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Electrical question: which outlet I can install based on what is available?
- Thread starter ZapZap
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- home charging
A 14-50 means that it uses a 50 amp breaker, not a 40 amp. Tesla only uses three wires, but it's not a good idea to wire up a 14-50 in this way because if someone plugs something like an RV into it, bad things will happen. Pull the extra wire and do it right. (also check the wiring size of the wires already there--they might not be adequate).
If you only have 3 wires and they are the sufficient gauge, you could do a 6-50 outlet instead of 14-50 and get the $35 6-50 adapter from Tesla. The Tesla adapter will limit the draw to 32 amps.
Gen 2 NEMA Adapters
Alternatively, you could put in a hardwired Tesla wall connector.
Gen 2 NEMA Adapters
Alternatively, you could put in a hardwired Tesla wall connector.
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It's perfectly legal (and to code) to install a 14-50 on a 40 amp circuit. But not with only three wires. The 6-50 is the way to go, assuming it's a 240v circuit (which I would think it would be; make sure it's the neutral wire that is missing).
zosoisnotaword
Member
Based on your post, you just need to hire a qualified electrician and let him give you options. Then you can decide which option to choose. Otherwise your username might turn into an experience.
The 6-30 would charge at the exact same speed without having to run an extra wire.
I know it’s okay to wire a 14-50 to a 40 amp circuit, but is it to-code to wire a 6-50 outlet to a 40 amp circuit?
Yes (well, 240v for two-phase residential). The NEMA 6 outlets are generally the same as the NEMA 14, minus the neutral. The neutral does give the NEMA 14's the ability to be used as 120v or 240v, which is beneficial in some situations but not necessary for charging a Tesla.
Yes, because there's not a 6-40 you are allowed to use the next higher outlet (same reason why it's ok to use the 14-50 on a 40 amp circuit). It's actually fairly common to use a 6-50 outlet on a 40 amp circuit for an electric range.
SomeJoe7777
Marginally-Known Member
Since there were two 40A circuits going to the garage junction box, does that mean that there are two sets of 3 wires, one set for each circuit? (i.e. black, red, green for 40A circuit #1, and another black, red, green for 40A circuit #2) ?
If that's the case, then what you could do is repurpose one of the wires from the other set as the neutral. This is legal and to code, but you have to mark the 4th wire with the proper color using tape. For example, take circuit #1's wires (black, red, green), and circuit #2's black wire and the 4 together can be made into a proper circuit for the 14-50 plug as follows:
1. Disconnect all 3 of the wires for circuit #2 at the breaker panel (remove black and red from the circuit #2 40A breaker, remove the green from the ground bar).
2. Tape white electrical tape to the black wire for circuit #2 on both ends (in the breaker box and in the garage junction box).
3. Connect this new black-marked-white wire to the neutral bar in the circuit breaker box.
4. Cap off the red and green wires from the old circuit #2 in the garage junction box, they will not be used.
5. Wire the 14-50 outlet using the 4 wires (black, red, green, and the new black-marked-white).
This gives you a 4-wire 40A circuit. Yes, it's legal and to code to use a 14-50 outlet on a 40A circuit. The reason this is allowed is because there is no NEMA outlet standard for a 40A outlet. To do this to code, the breaker must be 40A, and the wire must be the correct gauge for a 40A circuit, and the device plugged into the outlet must be a 40A or less device. This setup is very commonly done on residential electric ranges, which are typically 40A devices and they are plugged into a 14-50 outlet on a 40A circuit.
If that's the case, then what you could do is repurpose one of the wires from the other set as the neutral. This is legal and to code, but you have to mark the 4th wire with the proper color using tape. For example, take circuit #1's wires (black, red, green), and circuit #2's black wire and the 4 together can be made into a proper circuit for the 14-50 plug as follows:
1. Disconnect all 3 of the wires for circuit #2 at the breaker panel (remove black and red from the circuit #2 40A breaker, remove the green from the ground bar).
2. Tape white electrical tape to the black wire for circuit #2 on both ends (in the breaker box and in the garage junction box).
3. Connect this new black-marked-white wire to the neutral bar in the circuit breaker box.
4. Cap off the red and green wires from the old circuit #2 in the garage junction box, they will not be used.
5. Wire the 14-50 outlet using the 4 wires (black, red, green, and the new black-marked-white).
This gives you a 4-wire 40A circuit. Yes, it's legal and to code to use a 14-50 outlet on a 40A circuit. The reason this is allowed is because there is no NEMA outlet standard for a 40A outlet. To do this to code, the breaker must be 40A, and the wire must be the correct gauge for a 40A circuit, and the device plugged into the outlet must be a 40A or less device. This setup is very commonly done on residential electric ranges, which are typically 40A devices and they are plugged into a 14-50 outlet on a 40A circuit.
No, as far as I can tell there are only 1 set of 3 wires (there may be another set going to a different box that I haven't found yet). I'm going to test the voltage and if it's 240 then a 6-50 sounds like the way to go.
M3BlueGeorgia
Active Member
as long as the wires are of proper gauge. You would also need to tape the white wire to let future people know that it is hot.
XHabjab
TSLA Bull
I'd suggest buying an HPWC and get an electrician to legally wire it to the two hot wires and ground. This configuration doesn't need the neutral. Check on the gauge of the wiring. If it is sufficient size, you can use a bigger breaker on the circuit.
Put your portable adapter in the frunk and use it at RV parks.
Put your portable adapter in the frunk and use it at RV parks.
Nice. @Runt8 has stuff correct all throughout this. I'll concur with a few summary points:
There is no good purpose to pulling any extra wire to get a 4-wire setup. Charging an electric car only needs the higher power of the 240V connection. There is no reason to need the dual voltage capability of 120V/240V with the neutral.
Yes, the 6 series of outlets are for 240V only connections.
Yes, a 6-50 could be allowed on a 40A circuit.
I would recommend checking the gauge of the wire just to make sure it is sized right. Don't just assume based on what breaker size you see. People can do ridiculous electrical stuff, so I wouldn't trust the previous homeowner.
There is no good purpose to pulling any extra wire to get a 4-wire setup. Charging an electric car only needs the higher power of the 240V connection. There is no reason to need the dual voltage capability of 120V/240V with the neutral.
Yes, the 6 series of outlets are for 240V only connections.
Yes, a 6-50 could be allowed on a 40A circuit.
I would recommend checking the gauge of the wire just to make sure it is sized right. Don't just assume based on what breaker size you see. People can do ridiculous electrical stuff, so I wouldn't trust the previous homeowner.
Oh yeah--definitely that. Three wire cable is usually black, white, and bare copper for the ground. You are allowed to use that for a 240V connection, but you are required to mark both ends of the white wire to indicate that it is not being used for the usual neutral, but is a hot line instead.
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