NEMA 14-50 now Tesla Home Supercharger Later?

[Kelr316]

My question is if I decide to have my garage wired now for a 14-50 NEMA plug, can I change it and add a home supercharger unit at a later date? (assuming I initially install the correct wiring required for the supercharger). Thanks!

 

[DirtyT3sla]

So there is no home supercharger. What you're probably thinking about is the wall charger. The wall charger is slightly faster than a NEMA 14-50 outlet, and looks nicer, but is not normally worth the cost. I've had my 3 for 1.5 years and only use a NEMA 14-50. If you go that route, no need to upgrade unless it's for aesthetics.

Nema 14-50 will get you ~29 miles an hour. Wallcharger will get you somewhere around 42 miles an hour if you get 60 amps.

 

[Kelr316]

So there is no home supercharger. What you're probably thinking about is the wall charger. The wall charger is slightly faster than a NEMA 14-50 outlet, and looks nicer, but is not normally worth the cost. I've had my 3 for 1.5 years and only use a NEMA 14-50. If you go that route, no need to upgrade unless it's for aesthetics.

Nema 14-50 will get you ~29 miles an hour. Wallcharger will get you somewhere around 42 miles an hour if you get 60 amps.

Thanks! Sorry I confused the terms I knew that the home Wall charger is not a “supercharger”. So as long as I wire the NEMA 14-50 to a 60 amp fuse I could theoretically add a wall charger later if I want it to?

 

[thefortunes]

So there is no home supercharger. What you're probably thinking about is the wall charger. The wall charger is slightly faster than a NEMA 14-50 outlet, and looks nicer, but is not normally worth the cost. I've had my 3 for 1.5 years and only use a NEMA 14-50. If you go that route, no need to upgrade unless it's for aesthetics.

Nema 14-50 will get you ~29 miles an hour. Wallcharger will get you somewhere around 42 miles an hour if you get 60 amps.

Since you're being pedantic, there is no wall charger either.

The charger is in your car. The wall connector is what you are referencing.

The mobile connector and a NEMA 14-50 outlet are not designed for daily plugging/unplugging. If you leave the mobile connector plugged into the outlet and use it primarily at home then your advice holds.

There are other reasons to get the wall connector that have been discussed many times on this forum. Do a search.

 

[Pluturi]

So as long as I wire the NEMA 14-50 to a 60 amp fuse I could theoretically add a wall charger later if I want it to?

No. A 14-50 is wired with a 50A breaker and corresponding wiring which meets the electrical code for a 14-50. To go to 60A for a Wall Connector requires different wiring, not just changing the breaker.
Of course you can over specify the wiring for the 14-50 and future proof your installation, but you have to be clear with your electrician that’s what you’re doing or you won’t get the correct wire.

 

[ThePlankeEye]

If you have it installed with #6 AWG, and you can swap to the charger and a 60 amp breaker at a later date, assuming you have space in your breaker panel.

 

[Pluturi]

This is correct if the #6 wire is in a conduit or metal clad. Not true if you use 6/3 Romex which is what an electrician will use absent other guidance because it is easiest.

 

[ThePlankeEye]

I have 6/3 Romex on inaccessible rafters going to 1.5” conduit for the section outside (protect from the outside elements). Romex is fine for me.

 

[user212_nr]

So as long as I wire the NEMA 14-50 to a 60 amp fuse I could theoretically add a wall charger later if I want it to?

You are better off just purchasing the wall connector upfront and having the electrician install it.

Another thing that you can do is to wire the wall connector with a NEMA 14-50 plug. It will only charge at 50A though.

 

[MY-Y]

You can save a little using a 6-50 instead of a 14-50. Neither the mobile connector nor the HPWC needs a neutral wire.

I ran 4/3 gauge copper to both my HPWC and an additional 14-50 (for future). If I was doing it again, I would have used 4/2 and a 6-50.)

If you are considering swapping an outlet for a Tesla HPWC in the future, there is an important step you must take. You'll need about 6" more wire for the HPWC, so make sure you keep some extra wire in the wall that you can pull out later.

NM wire has a 60C temperature rating. 6 gauge is rated for 55 amps, 4 gauge is rated for 70. For the HPWC to provide 48 amps continuously, you need a circuit that has 48/0.8=60 amp capacity.

There is apparently an exception in the code allowing a 60 amp breaker on a 55 amp wire, but when buying the wire for this purpose, I'd just get one rated for this load.

 

[SSedan]

Other factors to consider are unexpected failure having a backup charging plan is prudent. Maybe it is a nearby public or neighbor's L2 or supercharging.
For me my UMC in my backup and the wall connector is the primary.

Also people mention the 14-50 not being meant for daily plug and unplug which is true and leaving a UMC connected is fine. What to hey neglect to consider is the handle and port at the car end while MUCH better suited for daily cycling do wear as well. My UMC1 handle runs warmer at 40amps than my wall connector does at 72amps.......
It was the primary charging source for 75-80k miles and 4 years. It is exhibiting wear, which is reasonable it has seen many thousands of cycles.

I have a 6yo S with 97k and dual 40amp chargers I only "need" the high amperage capability a time or two a year but it was a family emergency where I needed it and didn't have it that caused me to buy the wall connector and install it at maximum amperage.

 

[Johnny Vector]

You can save a little using a 6-50 instead of a 14-50. Neither the mobile connector nor the HPWC needs a neutral wire.

I ran 4/3 gauge copper to both my HPWC and an additional 14-50 (for future). If I was doing it again, I would have used 4/2 and a 6-50.)

If you are considering swapping an outlet for a Tesla HPWC in the future, there is an important step you must take. You'll need about 6" more wire for the HPWC, so make sure you keep some extra wire in the wall that you can pull out later.

NM wire has a 60C temperature rating. 6 gauge is rated for 55 amps, 4 gauge is rated for 70. For the HPWC to provide 48 amps continuously, you need a circuit that has 48/0.8=60 amp capacity.

There is apparently an exception in the code allowing a 60 amp breaker on a 55 amp wire, but when buying the wire for this purpose, I'd just get one rated for this load.

Yes, 240.4(B) allows the next higher standard breaker size if the wire ampacity doesn't match a standard breaker and there is only one thing on the circuit, meaning you can use 55 A wire (6 gauge NM) with a 60 A breaker

But 210.20(B)(1) says if there's exactly one outlet it needs to be rated at least equal to the breaker. So a 14-50 or 6-50 can not have a 60 A breaker.

So apparently (unless there's something else hidden in the code) you can use 6/3 NM wire with a 50 A breaker for a 14-50 now, and later replace the 14-50 with a direct-wired HPWC and change the breaker to 60 A.

However: If your jurisdiction uses the latest (2020) version of the NEC, or you want to meet it because safer is better, a 14-50 in a garage requires a Ground Fault Circuit Interrupter. This may be true in the 2017 code too; I forget when it changed. And a 50 A GFCI is $100, vs. about $10 for a regular breaker. (Protip: for some reason at least for Square D Homeline, their 50 A GFCI is $10 cheaper if you buy it inside a covered panel. They call it a spa pane. You can pull out the breaker and use the little panel box as a prop in your next monster movie or something.)

 

[Feathermerchan]

I can add about 10% of charge an hour or about 27 miles per hour using my Nema 6-50 (like the 14-50 without the neutral). So in 7 hours I can add about 190 miles of range. So the question is: How much driving do you do? I never use a supercharger near me. If I a, taking a trip, I'll stop at the nearest convenient supercharger which may be 90 to 200 miles away.
You may not need anything more than a 14-50.

 

[SSedan]

I got by on a 14-30 for a year because my commute is 15miles round trip. What convinced me to do the wall connector was we were on vacation when we got the call my Dad had a heart attack and was getting a 2 hour ambulance ride, Mom who normally doesn't drive far is following. I had to end my vacation rush home to drop off the wife and kids plugged in the car while we emptied it. Got little charge because of the limited current available and ended up having to hit a supercharger on the way to the hospital. If I had been able to charge at 52miles added per hour like I can now I could have spent 10 extra minutes at home and skipped that supercharging detour.

Those arguing that all you have to consider are today's car and commute are rather narrow minded.

Now granted the modern cars don't get the huge boost in charge rate my old S does with the dual chargers but long as it doesn't mean thousands in service upgrade I think overkill is prudent. Plan for the worst or the future, the extra capacity doesn't hurt

 

[Pluturi]

So apparently (unless there's something else hidden in the code) you can use 6/3 NM wire with a 50 A breaker for a 14-50 now, and later replace the 14-50 with a direct-wired HPWC and change the breaker to 60 A.

I think 625.41 makes the case that the conductor must be able to handle 125% of the continuous load and there is no “round up” rule like there is for breakers. Since the 6/3 Romex ampacity limit is 55A, the maximum current allowed would be 44A. Therefore, if one installs the Wall Connector they cannot use it at its rated capacity of 48A. Not sure that manually configuring it to run at a lower current would meet the code. It seems like it would be a better idea to just use the right wire for the ultimate application rather than try to justify changes after the fact.

 

[mycroftxxx]

However: If your jurisdiction uses the latest (2020) version of the NEC, or you want to meet it because safer is better, a 14-50 in a garage requires a Ground Fault Circuit Interrupter. This may be true in the 2017 code too; I forget when it changed. And a 50 A GFCI is $100, vs. about $10 for a regular breaker.

So if you do this then update to the HPWC later, you’ll have to change the breaker - the Gen-3 HPWC has GFCI built in and won’t work right with a GFCI breaker. Likely not a big deal, but something to remember.

 

[Watts_Up]

I think 625.41 makes the case that the conductor must be able to handle 125% of the continuous load and there is no “round up” rule like there is for breakers. Since the 6/3 Romex ampacity limit is 55A, the maximum current allowed would be 44A. Therefore, if one installs the Wall Connector they cannot use it at its rated capacity of 48A. Not sure that manually configuring it to run at a lower current would meet the code. It seems like it would be a better idea to just use the right wire for the ultimate application rather than try to justify changes after the fact.

Don't the length between the plug and the circuit breaker needs also to be evaluated when determining wires type?

 

[Johnny Vector]

Don't the length between the plug and the circuit breaker needs also to be evaluated when determining wires type?

Well at some point you might want to do that, but I don't think the code cares about total voltage drop. The code is about fires, so regarding wire size it's mainly concerned with power dissipation per unit length of the wire. At some length the total voltage drop starts to matter for making sure what you have connected continues to work, but for anything you're going to put in your house (say, less than 100 feet of run) it's safe in general to assume that if it meets code the voltage drop will not be a problem.

If you do want to calculate voltage drop, there are plenty of wire tables that give ohms per 1000 feet (or meters) for each wire gauge, so you can just multiply by the current to get your total voltage drop. Don't forget to multiply by 2, since there's a conductor in each direction!

 

[Johnny Vector]

I think 625.41 makes the case that the conductor must be able to handle 125% of the continuous load and there is no “round up” rule like there is for breakers. Since the 6/3 Romex ampacity limit is 55A, the maximum current allowed would be 44A. Therefore, if one installs the Wall Connector they cannot use it at its rated capacity of 48A. Not sure that manually configuring it to run at a lower current would meet the code. It seems like it would be a better idea to just use the right wire for the ultimate application rather than try to justify changes after the fact.

Agreed. Even with the price of copper being what it is, it's best to not skimp when pulling the wire. Most of the cost is still labor. Even if you pull the wire yourself, any reasonable valuation of your time says you don't ever want to have to replace the wire. Or worry about whether it's just on the edge of being safe.

The number of people in the US who die in house fires is 3x lower now than it was in, say, 1970. With 50% more people living here. Mainly because of improvements in the code. Think about that if you ever feel like cheating.

 

[Johnny Vector]

Don't the length between the plug and the circuit breaker needs also to be evaluated when determining wires type?

Well at some point you might want to do that, but I don't think the code cares about total voltage drop. The code is about fires, so regarding wire size it's mainly concerned with power dissipation per unit length of the wire. At some length the total voltage drop starts to matter for making sure what you have connected continues to work, but for anything you're going to put in your house (say, less than 100 feet of run) it's safe in general to assume that if it meets code the voltage drop will not be a problem.

If you do want to calculate voltage drop, there are plenty of wire tables that give ohms per 1000 feet (or meters) for each wire gauge, so you can just multiply by the current to get your total voltage drop. Don't forget to multiply by 2, since there's a conductor in each direction!