Building a new home, charging advice

[Redline]

We're going to be building a new custom home, and I want to have the house ready for both my R1S, and whatever future potential EV we might get to replace my fiancés Rav4 Hybrid.

Our first design meeting is in a month, and the builder already had said they usually build all their homes with dual charging ready to go. I did mention to him I'd probably want the Rivian wall charger for mine, and just have something ready to go for the future other vehicle.

I am very new to the charging dynamics of EVs, so I am curious to those here with more expertise. If you could start from scratch in a new home, what would you have for your charging solutions?

Thanks!

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[RBR1S]

Assuming you aren't doing an insane budget (you know, installing your own DCFC), a NEMA 14-50 for each car bay with all of them on their own master breaker (possibly even their own meter depending on the power company willingness), separate from the rest of the house's master breaker.

Why a 14-50 vs 6-50? You get the extra neutral which gives you more options in the future should a new standard be created and installation cost is minimal during build vs later. Also make sure that each 14-50 is setup with its own 60amp 50amp breaker due to the 80% rule. *ammended to 50, consult your electrician*

At some point, utility company may give better rates for home charging/off hours charging, which is why I recommend the separate meter option. The separate master breaker is to avoid any issues (say you were charging all of them and it caused too much draw, you only trip the breaker for the cars, not the entire house).

As for hard wiring, its an option but then you are limited to that charger until you hardwire a new one. Sockets give you more flexibility.

Just me and my simple thoughts.

 

[Redline]

Great feedback. I was thinking about just having dual 14-50s as an option.

Is there really any benefit of having the Rivian wall charger over a 14-50 nema?

 

[ajdelange]

I did mention to him I'd probably want the Rivian wall charger for mine, and just have something ready to go for the future other vehicle.

A charger is pretty much a charger. You can charge a Rivian from a Tesla charger and conversely. Perhaps the Tesla HPWC have a small advantage in that they can be managed through WiFi so that, for example, a pair that are capable of 48A each can be setup to share 48A such that they would get 24A each of being used simultaneously.

The main consideration in my way of thinking is where the charge ports are located on the vehicles you think you may buy. For example, for Teslas you want the EVSE driver's side rear whereas for Rivians you want them driver's side front. If possible you want to keep the cable off the floor. Proper location of the EVSE allows that but there are other arrangements that do too (hangars).

 

[RBR1S]

Great feedback. I was thinking about just having dual 14-50s as an option.

As a mental note, *and I adjusted my post* make sure that each 14-50 is set with a 60amp breaker as you don't want to load beyond 80%, (yes, I'm aware thats 83%, but anyway).

 

[ajdelange]

Why a 14-50 vs 6-50? You get the extra neutral which gives you more options in the future should a new standard be created and installation cost is minimal during build vs later.

I always have the electrician pull 3 conductor wire even for hard wired EVSE. It's very unlikely that a new standard using the neutral will ever come along but you don't know that you will always have EVSE in that spot. 6-50's are pretty rare these days but 14-50 is very common.

As for hard wiring, its an option but then you are limited to that charger until you hardwire a new one. Sockets give you more flexibility.

There is a cost and that is 8A charging current. Hardwired units are limited to 48A charging current (the maximum the vehicles will take) but plug in units may take no more than 40A and many of them are limited to 32.

 

[Redline]

When we get the electrical plans, I'll probably share them here to get feedback That is not my area of expertise.

 

[ajdelange]

As a mental note, *and I adjusted my post* make sure that each 14-50 is set with a 60amp breaker as you don't want to load beyond 80%, (yes, I'm aware thats 83%, but anyway).

A 14-50R must be wired to a 50A or 40A breaker (with this, i.e. the 40, being the reason many plug in EVSE are limited to 32A). Go back and change 60A to 50A.

 

[SilverII]

I built my house in 2020 and added only 1 Nema 14-50 outlet on one side of the garage. If I had to do it again, I would add another or hardwire on the other side of the garage. Put it on a 60 amp breaker

If you have 2 ev, it is much nicer to not have to share charger

 

[RBR1S]

A 14-50R must be wired to a 50A or 40A breaker (with this, i.e. the 40, being the reason many plug in EVSE are limited to 32A)

While this is true that a 14-50 receptacle does have a limited rating of 50A, the larger breaker allows the 80% margin (48A). It is common (I'm not sure if it's a standard) but you will find a 15A plug such as a 5-15 standard plug installed on 20A breakers, again the 80% rule (in that case 75%).

The other reason to use a 60A breaker is that if you DO hardware a device, hardwire bypasses the 50A limit of the receptacle and you have still standardized breakers vs having some 50 and some 60.

*as always, work with a licensed electrician when doing installs and follow code *

 

[chrismc]

I would have them install a 125A sub panel in the garage close to where you want to charge, and then it will be super easy to add and upgrade the charger(s) for your EV(s) now and in the future as things change.

 

[RBR1S]

many plug in EVSE are limited to 32A). Go back and change 60A to 50A.

Also, the EVSE I plan on getting is not limited to 32a. I'd suspect many aren't and the 32a issue is widely discussed among people having older chargers and or Tesla which did limit to 32A.


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[ajdelange]

While this is true that a 14-50 receptacle does have a limited rating of 50A, the larger breaker allows the 80% margin (48A).

Code requires that a 14-50R receptacle be wired to a 50A or 40A circuit meaning, respectively, a 50A or 40A breaker and the proper sized wire for the breaker choice. The ability to choose 40 or 50 for this receptacle is unique (other than the 5-15, 5-20). The derating is applied to the circuit. Thus the 50A circuit must be derated to 40A and the 40A circuit t 32.

It is common (I'm not sure if it's a standard) but you will find a 15A plug such as a 5-15 standard plug installed on 20A breakers, again the 80% rule (in that case 75%).

In this case the number of outlets and type on a 20A breaker is not specified (but there are some rules of thumb). The 80% derating does not apply in this case because the loads plugged into a 5-15 or 5-20 are not continuous loads. EVSE, by definition, are.

*as always, work with a licensed electrician when doing installs and follow code *

That's what I am suggesting you do.

 

[netcam]

I would install a 125-150 amp subpanel in the garage, this will be useful for many other things in the future. More importantly, I would ensure the wire run to the subpanel and EVSE locations are in conduit so in the future you can make changes without ripping up walls.

You might also consider requirements for future bidirectional charging as well.

 

[JaMa]

We're going to be building a new custom home, and I want to have the house ready for both my R1S, and whatever future potential EV we might get to replace my fiancés Rav4 Hybrid.

Our first design meeting is in a month, and the builder already had said they usually build all their homes with dual charging ready to go. I did mention to him I'd probably want the Rivian wall charger for mine, and just have something ready to go for the future other vehicle.

I am very new to the charging dynamics of EVs, so I am curious to those here with more expertise. If you could start from scratch in a new home, what would you have for your charging solutions?

Thanks!

I built my new home in 2019 and set it up for charging as well as solar.

So, your mileage may vary but I did the following:

1. I installed 2x 80 amp circuits on the garage wall in front of where I park, one for each potential EV.
2. I have a separate shutoff right next to each charge location, where I have the option to hardwire in anything I want up to 80 amps.
3. On one of the circuits I have the latest generation Tesla wall connector, mounted to a piece of color matched painted MDF.
4. On the other circuit I have a 48a wallbox with the standards-based 1772 connector.

This setup gives ultimate flexibility for the future. My Tesla will charge on either one, but I can also charge anything else standards-based on the other bay. I have it setup so either cable will reach either garage bay. At some point I will remove the Tesla connector/unit and put in a standards based one. Because of the shutoffs and mounting situation, I have the flexibility to do so. Because of where they are my setup will work for whatever shows up far into the future.

Hope this helps,
J

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