AWG to future-proof installation for HPWC

[KayZee]

I plan to install a NEMA 14-50 now, but in the future, I'd like to (easily) upgrade to a HPWC.

Cable length: ~15 feet.

TODAY'S PLAN:
- 50A breaker
- NEMA 14-50 industrial outlet
- #6 AWG (6/3)
UMC will charge at 32A

FUTURE PLAN:
- Upgrade the breaker to 60A (there's room in my panel)
- Swap in the HPWC.
I want to make sure that I can charge at 48A.

Is #6 AWG (6/3) acceptable for the HPWC with a 60A breaker?

 

[eprosenx]

I plan to install a NEMA 14-50 now, but in the future, I'd like to (easily) upgrade to a HPWC.

Cable length: ~15 feet.

TODAY'S PLAN:
- 50A breaker
- NEMA 14-50 industrial outlet
- #6 AWG (6/3)
UMC will charge at 32A

FUTURE PLAN:
- Upgrade the breaker to 60A (there's room in my panel)
- Swap in the HPWC.
I want to make sure that I can charge at 48A.

Is #6 AWG (6/3) acceptable for the HPWC with a 60A breaker?

Lol, none of the above.

“It depends”.

“Yes” - If that #6 awg copper is in conduit.

“No” - If you are talking about #6 awg romex (NM) cable.

Edit: I just realized you said 6/3 which implies romex (NM cable), so I am changing my answer to no. Either upgrade to 4 awg (really stiff to work with) or go in conduit. I went conduit and am very happy, but either way works.

 

[KayZee]

Lol, none of the above.

“It depends”.

“Yes” - If that #6 awg copper is in conduit.

“No” - If you are talking about #6 awg romex (NM) cable.

Edit: I just realized you said 6/3 which implies romex (NM cable), so I am changing my answer to no. Either upgrade to 4 awg (really stiff to work with) or go in conduit. I went conduit and am very happy, but either way works.

Just to be clear, to support a future 60A HPWC, I would need either:

- 6/3 (NM cable) with conduit
or
- 4/3 (NM cable) without conduit

Is that correct?

Note: if it matters, this is an interior (basement to closed garage) installation.

 

[KayZee]

And is it safe to use #6/3 (NM cable) without conduit for the NEMA 14-50 and 50A breaker?

 

[ucmndd]

So 6/3 would need to run in conduit for a future 60A installation or I could run 4/3 with no conduit?

“6/3” implies “Romex”, a bundle of conductors inside a nonmetallic sheath. You don’t put that in conduit.

Your choices are individual 6 awg THHN conductors inside a conduit, or 4/3 Romex.

If you’re planning on a wall connector in the future, use conduit.

 

[ucmndd]

And is it safe to use #6/3 (NM cable) without conduit for the NEMA 14-50 and 50A breaker?

Yes. 6/3 romex is rated for 55A, which is why you can use it for a 50A circuit but not a 60.

 

[P85_DA]

Just to be clear, to support a future 60A HPWC, I would need either:

- 6/3 (NM cable) with conduit
or
- 4/3 (NM cable) without conduit

Is that correct?

Note: if it matters, this is an interior (basement to closed garage) installation.

Semantics matter ...copper = individual wires ..NM generically used as Romex where all three cables are sheathed

Individual cables require running in conduit ...Rome’s you can run in wall w/o conduit

 

[KayZee]

Thanks everyone. Luckily I'm not doing this myself but I wanted to get some info so I know what I'm talking about.

I'm leaning towards 6/3, 50A and the 14-50 outlet and not worrying about the future. The thought about future proofing was if I get a second Tesla in 2-4 years. Today, I don't need the HPWC because I charge overnight and I only use about 20-25% battery per day. My electrician is likely charging me $100 CAD or less to do the NEMA install.

From my calculations:

NEMA 14-50
- 50 amp breaker; 240V
- 48 km/hr charge rate
- 9.8 hours for 0-90%
- 7.7 hours for 20-90%

HPWC
- 60 amp breaker
- 71 km/hr charge rate
- 6.6 hours for 0-90%
- 5.2 hours for 20-90%

 

[MrMassTransit]

I think that makes sense. In the future, you could always upgrade your charging speed slightly by replacing the 14-50 with an HPWC, which would allow you to charge at 40 amps rather than 32 with the UMC. Generally, most people don't need as high capacity as they think they do.

Due to panel capacity, I have a 30 amp setup and it works perfectly fine for my needs. If I get home at 11 PM and need to leave at 8 AM the next day, I can add 200 miles to the car overnight. In reality, taking two back to back long trips (with a stop at home in between) is not something I ever do. Worst case I can always stop at a supercharger.

I'd go with the 6/3 NM cable and a 40 amp breaker. There's still benefit to upgrading to a HPWC down the road if you decide that's something you want to do. Even if you get a second EV in the future and wanted to charge them both simultaneously, a 40 amp connection will add about 135 miles in a 9 hour period overnight (at the Model 3 rate) to each vehicle with two HPWCs sharing the circuit.

Normally I'd say get it quoted both ways, because labor is usually the biggest line item in an install. But if you can get this done for under $100 CAD, I'd just go with the 40 amp.

 

[eprosenx]

I think that makes sense. In the future, you could always upgrade your charging speed slightly by replacing the 14-50 with an HPWC, which would allow you to charge at 40 amps rather than 32 with the UMC. Generally, most people don't need as high capacity as they think they do.

Due to panel capacity, I have a 30 amp setup and it works perfectly fine for my needs. If I get home at 11 PM and need to leave at 8 AM the next day, I can add 200 miles to the car overnight. In reality, taking two back to back long trips (with a stop at home in between) is not something I ever do. Worst case I can always stop at a supercharger.

I'd go with the 6/3 NM cable and a 40 amp breaker. There's still benefit to upgrading to a HPWC down the road if you decide that's something you want to do. Even if you get a second EV in the future and wanted to charge them both simultaneously, a 40 amp connection will add about 135 miles in a 9 hour period overnight (at the Model 3 rate) to each vehicle with two HPWCs sharing the circuit.

Normally I'd say get it quoted both ways, because labor is usually the biggest line item in an install. But if you can get this done for under $100 CAD, I'd just go with the 40 amp.

With 6/3 romex I would do a 50 amp breaker. I don’t like a 14-50 on a 40 amp circuit if I can avoid it. Since that wire is good for 50a I would do a 50a breaker.

 

[MrMassTransit]

With 6/3 romex I would do a 50 amp breaker. I don’t like a 14-50 on a 40 amp circuit if I can avoid it. Since that wire is good for 50a I would do a 50a breaker.

I agree. Should have written 50 amp in my post above!

 

[67King]

You can set the wall charger to charge at 40 amps, in which case a 50 amp breaker would be sufficient, I believe. You can actually find 55 amp breakers, too, though that would be pushing it on the 48 amp setting

 

[KayZee]

Thanks everyone! I really appreciate the advice. It's enticing to get the HPWC just because but there really is no point for me based on my driving needs. I have a supercharger 5 minutes for those random worst case scenarios.

I think I've settled on the following and will worry about the future in the future

- NEMA 14-50
- 50 amp breaker
- 6/3 romex

 

[eprosenx]

You can set the wall charger to charge at 40 amps, in which case a 50 amp breaker would be sufficient, I believe. You can actually find 55 amp breakers, too, though that would be pushing it on the 48 amp setting

Your callout about a 55 amp breaker is an interesting one, but there are some issues.

So the NEC lists “standard” size breakers. These come in increments of five amps up to fifty amps, then they go up in ten amp steps through 100 amps. Now I think at least one manufacturer makes 55 amp breakers. Even if they did not though, I believe the “next size up” rule on the NEC allows you to use the next larger breaker but still you have to make sure the “load to be served” is less than or equal to the wire capacity.

Sadly though, Tesla does not provide a setting for 55 amps. They jump from 50 to 60 on the rotary dial (actually 40 to 48 really). Due to the 125/80% rule for continuous loads you need a circuit with a 60 amp rating (wire and breaker) in order to support 48 amps continuous.

So sadly, we can’t make use of all the rated capacity of wire.

I wish the wall connector let you set max amp charge rates in one amp increments (like using two rotary dials) since there are conditions where the rated ampacity is not one of those fixed settings (another example is when you have to derate wire due to number of conductors in a conduit or due to ambient temp). Or say due to total calculated load capacity for a “service” or feeder.

But I think this is too advanced for most installers, so they kept it simple.

 

[67King]

I wish the wall connector let you set max amp charge rates in one amp increments (like using two rotary dials) since there are conditions where the rated ampacity is not one of those fixed settings (another example is when you have to derate wire due to number of conductors in a conduit or due to ambient temp). Or say due to total calculated load capacity for a “service” or feeder.

That would be nice. I'm rewiring my 240V stuff in teh garage right now, and ended up just running a dedicated circuit for the charger off the main, rather than sub. And because of the difficulty in running stuff through the walls, I ended up going with 6/3, so I'm going to be limited to the 40 amp rate.

 

[SSedan]

MrMassTransit touched on it, I think you were a little confused on charge rate UMC plugged into a 14-50 only nets 32amps with the current UMC, where a wall connector is good for 40 on the same circuit. Been said already just didn't feel like the point was received. So even on the same breaker and wire a 25% gain.

I believe a secondary charging solution is just good planning. I drive 15-35 miles a day, have a wall connector on a larger circuit and the UMC stays in the car. I used the UMC for a year till an odd set of circumstances caused me to need a faster solution once, at which point I bought the wall connector and am happy I did rarely need the faster charging but happy to have it when I do.
Also while people stress over the cost of wire the THHN for a 100amp circuit is only $2.62 per foot 2-3guage and an 8guage ground, probably only a buck a foot more than a 50amp circuit. Granted it won't fit a 14-50 plug but the point is a one size wire upgrade is good insurance to be able to draw more later and does NOT cost much now. 14-50 wiring also needs a total of 4 wires where a wall connector only uses 3 again this makes the upgrade less costly than most folks make it out to be.

I see you are in Ontario, cold weather greatly increases energy use and charging starts slow if the pack is cold, 32amps is still sufficient but this will blow your calculations on how fast the car recovers from a days use out of the water. You want it anyway just spend the money on the wall connector on a 60amp or bigger circuit now, install 3 wires instead of 4, don't buy and outlet and save the repeat electrician trip.

 

[KayZee]

I ended up going with a 50A Nema 14-50 and 6/3 wiring. I ran the wire myself and an electrician who supplied all the materials connected everything up. Cost was $125 CAD.

I don’t believe I need the HPWC at home based on personal usage/habits and the fact that there is a free public charger 6 minutes away (72 km/hr), a supercharger 2 min. away and another supercharger on route to my work for those emergency situation.

Future plan could include a HPWC with my 50A breaker to increase charging if I’m totally wrong.

Thanks for all the help and suggestions everyone!

 

[233.3]

Consider running 1" conduit and whatever wire size you need for your current need. If you do decide to add another Tesla you can pull in a second circuit in the same conduit for a second HPWC or increase the wire size to support a 100 amp circuit to be shared by two HPWC's. Conduit gives you options.

 

[Pmurphjam]

I plan to install a NEMA 14-50 now, but in the future, I'd like to (easily) upgrade to a HPWC.

Cable length: ~15 feet.

TODAY'S PLAN:
- 50A breaker
- NEMA 14-50 industrial outlet
- #6 AWG (6/3)
UMC will charge at 32A

FUTURE PLAN:
- Upgrade the breaker to 60A (there's room in my panel)
- Swap in the HPWC.
I want to make sure that I can charge at 48A.

Is #6 AWG (6/3) acceptable for the HPWC with a 60A breaker?

Yes, #6 AWG 3 conductor will work. Black and Red are power and white goes to power neutral on your panel. It doesn't need ground. The Home Depot link below shows the wire that will work. You can tac this to your wall with clamps if it's in the garage where your main circuit panel hopefully is, no need to run conduit. You'll need a 60 Amp breaker, and set the WC dial to #9 for 48Amp draw. Model 3 LR won't draw more than 48Amps. Make sure you tighten the wires with 35 lbs of force in the WC and the circuit panel. I soldered the stranded wire ends together to get a good connection. You're drawing 48 Amps and bad connections will create heat and could burn up your WC and wire if you're not careful. To check when charging at 48 Amps for 20 minutes the #6 wire should be slightly warm but not hot as it comes into the WC, and the WC should run cool. The charging cable to your car will be slightly warm also. If you smell burning wire then your connections aren't tight enough or good.
Southwire (By-the-Foot) 6/3 Stranded Romex SIMpull CU NM-B W/G Wire-63950099 - The Home Depot

 

[Rocky_H]

Good grief.

Black and Red are power and white goes to power neutral on your panel. It doesn't need ground.

You have that backward. The wall connector does need ground but does not need neutral.

The Home Depot link below shows the wire that will work. You can tac this to your wall with clamps if it's in the garage where your main circuit panel hopefully is, no need to run conduit.

No. Electric code does not allow you to just tack Romex bundled cable bare on the outside of a wall. Conduit would be needed if it's outside the wall.