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Advice Needed for Install of Charger PLUS Outlet

Oct 11, 2020
87
72
Grand Rapids, MI
My electrician scouted out my situation and is coming to do an install next week. He's a great guy and knows his stuff but isn't familiar with EV chargers yet. I'm very particular about things and want to do this right. My electric panel is also a very long run from the garage so I don't to do my research and get this right the first time.

Here's the situation:

I purchased a Chargepoint EV Charger and that will charge at up to 50 amps if it's hardwired. My Model Y can only charge at 48 amps so I think a 60 amp run to the charger is perfect here. Here's where it gets tricky - I would also love to install a NEMA 14-50 on the other side of the garage because we might purchase another EV in the next few years.

So, how can i pull this off? My electrician suggested a 100 amp breaker and a 100 amp wire run to the garage and split. Assuming we get 100 amps to the garage he would have a junction box in the garage and we would have 60 amps going to the charger which would allow for charging at 48 amps since it would be hardwired. The concern is that only leaves 40 amps for a NEMA 14-50 plug. Is 40 amps enough? If so, that would only charge at 32 amps, right?

Can you think of a way to do this better? I'm wondering if we could do a 120 amp breaker and wire to get 60 amps each. Does that even exist? How fast can a NEMA 14-50 charge anyway? Maybe 40 amps is plenty and more would be wasted anyway?

Thanks all! I appreciate the feedback on this.
 

LNL_HUTZ

Member
Aug 3, 2020
299
233
San Francisco
Some totally uninitiated thoughts:
  1. Once you add a second EV, is it going to be necessary to charge both at the same time? Because if it isn't, you can obviously do with a single connector (probably one with a longer cable).
  2. I'm not familiar with the Chargepoint, but it's not uncommon for people to add a pigtail to their HPWC or other connector and use it with an outlet instead of hardwiring. You could consider doing that and giving yourself some flexibility for a future EV.
  3. If you're likely to go with another Tesla in the future, you might want to consider switching to HPWCs, which can be linked to work in concert.
 

mrau

Authorized Driver
Nov 12, 2018
412
791
Mid-Michigan
Believe a sub panel can only be 50% of your Main panel. If you have a 200 amp Main panel in basement, then 100 amp is the most you can run to a sub panel in the garage.

A 14-50 should be on a 50 amp circuit. The wire running to the outlet can be bigger for future upgrades, but the breaker must be no more than 50 amp.

You really won't notice much of a difference between charging at 48 amp v 40 amp. Most of your charging will probably be done after you have parked the car for the day. It will be "full" the next morning in either case. Lots of folks charge at 32 amps and don't even think about it anymore.

If the Chargepoint unit has a pigtail for a NEMA14-50, you could install two 14-50 outlets that would be conveniently located for you and plug Chargepoint into one of them. You could move the Chargepoint later if you happen to rearrange how you park your cars. No need to call the electrician back.

Just some ideas.
 
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Rocky_H

Well-Known Member
Feb 19, 2015
6,271
7,326
Boise, ID
Interesting and good questions. I'm glad to see you're not trying to tie them both on one 50 or 60 amp circuit. That would not be allowed.
So, how can i pull this off? My electrician suggested a 100 amp breaker and a 100 amp wire run to the garage and split. Assuming we get 100 amps to the garage he would have a junction box in the garage and we would have 60 amps going to the charger which would allow for charging at 48 amps since it would be hardwired. The concern is that only leaves 40 amps for a NEMA 14-50 plug. Is 40 amps enough? If so, that would only charge at 32 amps, right?
That probably is about the best solution you can do for this and would work perfectly.
Yes, NEC does allow a 50 amp type of outlet, like a 14-50 to be put on a 40A circuit, so that is allowed, and is pretty appropriate for this use anyway, since the mobile charging cable can only pull 32A maximum, so that fits the 80% rule for 40A circuits anyway, so sounds good. If you want to be a little extra detailed about it, you might want to put a label on the 14-50 outlet, though, letting people know it's only on a 40A circuit, but that's not required.

Believe a sub panel can only be 50% of your Main panel. If you have a 200 amp Main panel in basement, then 100 amp is the most you can run to a sub panel in the garage.
I don't know about limits of subpanels. If the subpanel could be 110 or 120A, then this would be really straightforward, so put 60 to the wall connector and 50 to the 14-50 outlet, but I was just going with the initial proposal of how to split a 100A subpanel.

A 14-50 should be on a 50 amp circuit. The wire running to the outlet can be bigger for future upgrades, but the breaker must be no more than 50 amp.
Yes, I do usually recommend people use a 50A circuit for them to be more appropriate and standard. 40A is allowed, but more than 50 is not allowed.
 

jcanoe

Active Member
Oct 2, 2020
2,176
2,151
Maryland
What is the specific model of your Chargepoint electric vehicle service equipment (EVSE)? Most people call it the charger but the correct term is EVSE. An EVSE that is rated for 50 amps probably means that it requires a 240V and 50 ampere dedicated circuit. Such an EVSE will be capable of charging at up to 40 amps. (EVSE are always limited to charging at a maximum of 80% of the circuit where they are connected.)

The NEMA 14-50 receptacle is rated for a maximum of 50 amps, normally would be installed on a 240V circuit with a 50 amp circuit breaker. As noted, the NEMA 14-50 can also be used with a 40 amp circuit; one reason is that there is no specific 40 amp rated receptacle or power plug so the NEMA 14-50 can serve as the 40 amp receptacle and power plug.

Even on a 50 amp circuit where the maximum allowed amperage for charging is 40 amps (80%) it is common to use 50 amp circuits with EVSE that are capable of supporting 32 amps instead of 40 amps. The reason is that the vehicle may not be capable of charging at more than 32 amps, also the EVSE (as is the case with the Gen2 Tesla Mobile Connector) may not be capable of more than 32 amps. Also, 40 amp capable EVSE are a bit more expensive than 32 amp capable EVSE. There are many more choices, available 32 amp rated EVSE than higher amperage EVSE but these certainly are available. If you decide to install the Tesla Wall Connector this EVSE can operate at up to 48 amps but it can also be configured, when installed, to operate a lower maximum amperage such as 40 amps or 32 amps. The reason to set the lower limit would be if the circuit that the Wall Connector was on must be less than a 60 amp circuit breaker because the electrical service within the home does not have capacity, cannot not support a new 60 amp circuit but could support a 30, 40 or 50 amp circuit. It is important when selecting an EVSE for a specific application to consider the location of the EVSE.

An EVSE that will be installed inside a garage is not exposed to the weather, does not need to be all-weather rated. The Tesla Wall Connector is all-weather rated, can be installed outdoors for use in all weather conditions if it is hard wired. The Tesla Mobile Connector is not all-weather rated, should not be left exposed to rain/sleet/snow. (Power receptacles and plugs, whether NEMA 5-15 or NEMA 14-50 are not all-weather rated.) You can purchase a weather housing for the receptacle/plug connection but this is not the same protection as a NEMA Level 3 or Level 4 rating for protection from water intrusion. A hard-wired installation of the EVSE, i.e. installation without a power plug, is required for all-weather service.

For most daily needs Level 2 charging at 32 amps or 40 amp are both more than adequate since you are probably charging in the evening or in the early morning hours. If you have a time of use (TOU) rate plan for your electricity usage this will almost always offer the least expensive cost per kWh between 1200 and 0600. At 32 amps you would be able to add up to 29 miles per hour of charging. At 40 amps you would be able to add as much as 35 miles per hour of charging. As you can see, over a 6 hour TOU off-peak charging period even the 32 amp charging would result in adding ~174 miles of driving range after charging the battery.

If the EVSE has a power plug this would be either a NEMA 14-50 or NEMA 6-50. If the Chargepoint EVSE does not come fitted with a power plug then it is intended to be hard wired at installation by a licensed electrician.

I would suggest you follow your electrician's suggestion and install a sub panel (typically these types of sub panels are rated for 100A or 125A.) Once you have the sub panel it becomes easy to install, add or move a circuit within the garage for charging one or more vehicles. The 100A panel could support (2) 40 or 50 amp circuits. A 60 amp circuit might mean that the second vehicle charging circuit could only be rated for 40 amps, ask your electrician.
 
Last edited:

Rocky_H

Well-Known Member
Feb 19, 2015
6,271
7,326
Boise, ID
I purchased a Chargepoint EV Charger and that will charge at up to 50 amps if it's hardwired. My Model Y can only charge at 48 amps so I think a 60 amp run to the charger is perfect here.
@jcanoe brought up a good point on the terminology here. These electric car charging devices have to comply with the code for continuous draw, so they can only supply a current that is 80% of what the circuit is rated for. So make sure you know which number that "50" is referring to. Is it for a 50A rated circuit? Then it can only supply 40A to the car. If that's saying supply 50A to the car, then that would need at least a 62.5A circuit, which would have to be on something bigger, like 65 or 70. That would be pretty unusual, so I'm guessing maybe that's a 50A circuit device, rather than a 60A one.
 

TomServo

Active Member
Apr 10, 2014
1,255
787
Belleville IL
I have been charging our Volt and Tesla with the Clipper Creek HCS-50P EVSE (the charger is in the car).
Iy5nnw3.jpg


It's overkill for the Volt but provides me 40 amps or 35 mph of charging on our Tesla. I opted for the plugged version for mobility and the fact I could get a 25 foot cord. My electrician used 6/3 AWG wire so should I ever decide to buy a Tesla Wall Connector we can just hardwire the Wall Connector and replace the breaker (60 amp) allowing me to charge at 48 amps or 45 mph.

If/when I sell the Volt the CC will go with it as a bonus. But I will miss the 25' cable.
 
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Rocky_H

Well-Known Member
Feb 19, 2015
6,271
7,326
Boise, ID
My electrician used 6/3 AWG wire so should I ever decide to buy a Tesla Wall Connector we can just hardwire the Wall Connector and replace the breaker (60 amp) allowing me to charge at 48 amps or 45 mph.
That's inside a wall, so is that 6/3 Romex? If so, then you cannot use that for a 60A circuit. It's only if it's separate wires in conduit that 6 gauge would be OK for a 60A circuit.
 

jstjohnz

Member
Sep 7, 2020
96
47
Indianapolis
I think Tesla should add another option in the wall connector setup, 44 amps, 55A breaker to allow legal 6/2 romex wiring. This would still meet code with a 60A breaker.
 

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