[SANZCO2]

So what happens if I just use the wire from the NEMA 14-50 instead of the THHN/THWN 55 amps versus 65 amps? I know that would increase my charge time, but we should only be talking a few hours more overnight. Is there any other benefits in going to 65 AMPs?

No issue you just need to set the charger to the proper setting. It would probably have a 50 amp circuit breaker, double check because you can do Nema 14-50 with a 40 amp as well. Based on the circuit breaker the dip switches on the charger would be set to pull 32 amps (40 amp breaker) or 40 amps (50 amp breaker). By code an EV charger should only pull 80% of the circuit on a continuous load.

 

[CommodoreAmiga]

6/3Romex has a max rating of 55 amps. You need you need 6 awg THHN/THWN 75C in conduit to get the 65 amp rating.

My understanding is the NEC lets you use the next-size-up breaker when the ampacity rating of the wiring falls between sizes. 6/3 Romex with a 60 degree C rating for 55A can be used on a 60A breaker and support a continuous load of 48A.

 

[ERivTruck]

Wow. Sooooo out of my league here. I have not recent post of new people taking delivery of their R1Ts, but is Rivian still offering the program to help people get set up with the wall charger? GM is offering an incentive program which is nice to get people to get a Level 2 charger properly installed in their residences.

 

[SANZCO2]

My understanding is the NEC lets you use the next-size-up breaker when the ampacity rating of the wiring falls between sizes. 6/3 Romex with a 60 degree C rating for 55A can be used on a 60A breaker and support a continuous load of 48A.

My understanding is that you can put a 60 amp breaker on the line but need to consider it to be rated at the lowest component in the circuit. I have actually put a 60 amp breaker on the circuit but limit the charging to 44 amps (80% of 55 amps). There are not a lot of chargers that allow to set at 44 amps but mine does.

 

[O. horridus]

is Rivian still offering the program to help people get set up with the wall charger

See Rivian

Rivian "partners" with QMerit. So does GM. So does Chevy, Subaru, Ford, etc. Supposedly this gives you a discount on the installation, but I have not heard of anyone who got a bargain price with QMerit - they seems to be on the high end of prices. I believe they contract out to local electricians, so essentially you're paying QMerit a finders fee on top of what you would pay the electrician.

 

[Wildabeest]

See Rivian

Rivian "partners" with QMerit. So does GM. So does Chevy, Subaru, Ford, etc. Supposedly this gives you a discount on the installation, but I have not heard of anyone who got a bargain price with QMerit - they seems to be on the high end of prices. I believe they contract out to local electricians, so essentially you're paying QMerit a finders fee on top of what you would pay the electrician.

The QMerit process was a pain. They may you take pictures of your outside service panel, inside breaker panel, etc. and enter a bunch of information. Then at the end of it all they want to charge you a fee to give you a price estimate for the install. No thanks.

 

[ERivTruck]

Ah this is good to know. I got my home builder's electrician programmed into my phone, I'll just reach out to him!

 

[Wildabeest]

Installed mine myself. Added a 60 amp breaker to my existing main panel (had to move a single pole breaker to another slot to make room for it). Fed about 10’ of 6/3 Romex straight up the wall from the panel in my basement and out into my garage, then into conduit up into the charger. It was about $100 in parts - most of that consumed by $85 for a 15’ spool of 6/3 Romex 😳). Easy-peasy and works like a champ.

 

[ERivTruck]

So a pulled about the housing on my NEMA 15-50 housing in my garage to expose the wires and see what gauge they are. Perhaps you all are better at this than me, but I could not see any gauge wire rating on the sheet of the Red, Black or White wires. However, they look and feel, very very thick to me. Can you glean any info from these pics? I really couldn't even pull the whole wire bundle from the wall as I was met with a lot of resistance to do that.

 

[ERivTruck]

Any thoughts on if these wires are "up-gauged" enough to handle a 60 AMP breaker?

 

[Wildabeest]

Any thoughts on if these wires are "up-gauged" enough to handle a 60 AMP breaker?

Any thoughts on if these wires are "up-gauged" enough to handle a 60 AMP breaker?

Hard to tell from the pic. Need to be AWG 6 or lower. You might want to pull the front panel off of your breaker box where you’ll have longer lengths of wire to see if they are labeled.

 

[ERivTruck]

Thank you. I'll try that this weekend and report back.

 

[Wildabeest]

Thank you. I'll try that this weekend and report back.

If they aren’t marked, you can get a wire gauge too and measure it. That will require you get to the bare wire though, so you’d likely need to pull one from its socket to measure it.

 

[CommodoreAmiga]

That wire looks like romex -- the conductors are bundled into an outer jacket. Those wires aren't rated individually, so the markings you need are on the OUTER jacket (you can see just the end of it coming through the grommet in the box). I'd go back to the load center and see if more of the outer jacket is visible and hopefully you can read that.

 

[ERivTruck]

That wire looks like romex -- the conductors are bundled into an outer jacket. Those wires aren't rated individually, so the markings you need are on the OUTER jacket (you can see just the end of it coming through the grommet in the box). I'd go back to the load center and see if more of the outer jacket is visible and hopefully you can read that.

Ahhh, that makes more sense. I could see some markings on the outer jacket of the "conduit", but I was not able to pull the whole wire bundle much more than 1/4" and I didn't want to risk pulling on it too hard. I should (I think) be able to remove the cover from my fuse panel and find the wire going into the box and (hopefully) see any markings on it. Looks like a weekend job for me.

 

[rhumbliner]

My understanding is the NEC lets you use the next-size-up breaker when the ampacity rating of the wiring falls between sizes.

You have to be careful when quoting the “next size up“ rule. That rule is explained here: StackPath and is part of a 7-step process when determining new installations. It does not give you carte blanche to blindly upsize breakers on existing circuits — especially continuous load circuits which applies to EV chargers. It is always safer to trust the cable manufacturer’s ampacity rating and size your breaker accordingly.

 

[ERivTruck]

Dear God! This is getting waaay confusing. You'd think that with EVs becoming the norm now, and people not being licensed electricians or EEs by trade, I can see a lot of future EV owners and DIY-ers trying this out and messing it up BIG TIME!

In my case, I'll probably be charging up from about 1700 HRS - 0600 HRS, so am I picking at fly poop here? Dunno. I figure I'll charge my R1T about 2 times a week to get through the work week, and maybe three times in a 7 day period.

 

[rhumbliner]

Dear God! This is getting waaay confusing.

Not really. Assuming you have a 50-amp breaker protecting 6-AWG NM-B wire that means your charge rate at 40amps is 240V x 40A = 9.6kW. Further assuming you have the 135kWh battery pack, that then means it would take 135kWh / 9.6kW = 14hrs to fully charge the battery. But wait, that’s unrealistic. Let’s say you get home at night with a 20% SoC and you intend to charge overnight up to 80%. That means your normal charge time will be 135kWh x 60% / 9.6kWh or roughly 8hrs which should be more than enough time.

Now compare that to what’s to be gained by upsizing your wiring and breaker to 60 amps. Then your charge rate becomes 240V x 48A = 11.5kW and your equation looks like this: 135kWh x 60% / 11.5kW or roughly 7hrs. So all this fretting over saving 1hr each night. Hardly seems worth it.

 

[Wildabeest]

Dear God! This is getting waaay confusing. You'd think that with EVs becoming the norm now, and people not being licensed electricians or EEs by trade, I can see a lot of future EV owners and DIY-ers trying this out and messing it up BIG TIME!

In my case, I'll probably be charging up from about 1700 HRS - 0600 HRS, so am I picking at fly poop here? Dunno. I figure I'll charge my R1T about 2 times a week to get through the work week, and maybe three times in a 7 day period.

It’s why most people will consult a licensed electrician for these things. It’s not for the faint of heart, but also not beyond the capabilities of a decent DIYer willing to do some research and educate themselves. You need to understand both the fundamentals of electricity and your local building codes.

 

[ERivTruck]

Now compare that to what’s to be gained by upsizing your wiring and breaker to 60 amps. Then your charge rate becomes 240V x 48A = 11.5kW and your equation looks like this: 135kWh x 60% / 11.5kW or roughly 7hrs. So all this fretting over saving 1hr each night. Hardly seems worth it.

Ahhhh TY. Now some in speaking my language! Math and equations! That makes a lot more sense. And in my opinion it is not worth it for 1-2 hours. I am a planner by nature and if (worst case) I need 14 hours to charge, I'll plan the night before to do that. I have NEVER had a cell phone run out of power at work because I always plan the charge ahead of time. Now....FORGETTING the phone at home, that's another story altogether!