Model S in Near Future...Garage Electrical Considerations

[Buster1]

Well, we're gonna pull the trigger on a Model S this fall! Not sure what options it will have, but I'm looking at CPO cars.

Anyway, I'm meeting my electrician this Wednesday for a quote, and I'm wondering what kinds of things I need to discuss or tell him. I've been reading a lot on here and I appreciate the knowledge in these threads, amongst many others.

Help me figure out home charging options
How much does Home Charging installation cost?

Can you guys check my math here? I'm leaning at a simple 14-50 (240v) outlet and the UMC. Gotta be AC...right? Should come off a 50A breaker, or maybe 2 for 100A and my box needs to be able to handle the juice? Hopefully he'll know those limits. Can we do a 100A to the 14-50 for a later upgrade to a HPWC?

For my installation, the breaker box is on the outside of the house, North wall. My car parks on the South side of the garage so I'm thinking (if codes allow) of running a conduit into the garage and up and over to the South wall for the 14-50. Too many kids and bikes and skateboards to stretch a cable along the floor every day.

I appreciate any insights or advice that I need to consider and discuss with the electrician.

Buster

 

[Algbc]

I had two HPWC installed in two different location.
at home I was able to use 100 Amp breaker, ( the house has 400 amp main barker). it was wired up to garage. I'm able to charge the car 52 km an hour which I'm okay with.
at work I had to use 50 Amp breaker ( 200 amp main breaker), and since we use a lot of electrical units that use a lot of power I had to set the HPWC to 40 amp. this charges my car 26 km an hour.
I was told if I like to use 100 amp for faster charge, I would have to call my electricity provider and ask them to provide me with new service, which included a new separate meter. its not ideal because it cost me $1700.00 to run a new service and install a new meter, and here in Toronto even if I do not use the electricity I still have to pay $26.99 for delivery of the electricity.

al the wiring was passed inside the walls and very minimal wires are visible.
as for pricing: to do the work at my house, it cost me $960.00 inducing material and labour. 6 hours to install
for work place, it was a little easier and the cost was $520.00 including material and labour. 4 hours to install.

 

[365gtb4]

I would wire for the the 80 amp HPWC now. You don't have to use the power but the cost to go back and rewire for more power will be like a new installation. Use the appropriate breaker for the plug you will use now. Breakers are cheap, installing new conduit and wire isn't. Plan for the future and the upgrade cost will be minimal. Put the plug as close to your vehicle's receptacle as you can. Remember you will probably plug the car in daily and a short run is just easier to handle and less likely to be damaged.

 

[Ugliest1]

My one bit of technical knowledge is whatever your amperage rating is, the delivered power will only be 80% of it -- that's to code and from TMC comments I think that's universal across North America. I.e., @Algbc's line protected by the 50A breaker can only legally deliver 40A continuous power, and also, @Algbc's voltage at work is probably only 208V (commercial limit) not your home 240V (so you would get more than 26kph if you put that in yours).

 

[jerry33]

Neither the UMC nor the HPWC cables are very long considering that about 1.5 to 2 m are taken up by going from the car to the ground and the outlet to the ground, so you want to have the outlets somewhat near to where the charge port on the car is.

The HPWC's main advantages are: Can charge two cars (IMHO the main advantage), slightly longer cable, one less connection (the second main advantage), and can be set to use a variety of circuit amperages. For most folks, the difference in charging speed (assuming a 100 amp circuit) doesn't mean much unless you have a very short TOU because a 50 amp circuit with the UMC will fully charge in six to eight hours.

The cost of a home installation varies depending upon the length of cable run and the difficulty of running it. Be sure to get several quotes as they are almost sure to vary by a significant amount. Because a lot of the cost is just getting the electrician out there, I'd suggest also putting in a 14-50 so that you have a reasonable speedy backup in case the HPWC should have an issue. (or two 14-50 if you go the 14-50 way). The additional cost of the extra wires, circuit breaker, and receptacle is very minimal.

 

[xyeahtony]

You cannot install an outlet rated for 50amp on a 100 amp breaker, that kind of defeats the purpose of the breaker.

I would just spring the money now for a 60 amp breaker and wall charger for 48 amp charging. You honestly do not need full 100amp service unless you're getting a 100D and its going to be a lot bigger of a PITA to route 3 gauge wire vs 6 gauge wire. 100 amp breakers are like $55 as well vs $8 for a 60amp.

A wall connector will be cleaner too vs having an outlet and your UMC lying around on the ground while you're away.

 

[David.85D]

50 amp outlet on a 100 amp circuit isn't the only way (and wrong way) to plan for future upgradability.

If you are thinking you might want 100 amp circuit (80 amp charging on one or two hpwc), but you intend to start with a 50 amp circuit (40 amp charging), then the electrician could size the wire for 100 amp (around 3 gauge, depending on the run) but install a 50 amp breaker and 50 amp plug. Everything is properly protected this way. Then, in the future, you can have the electrician come back and install the HPWC and change the breaker to 100amp.

All of this is assuming the panel can handle 100 amp load. If it can't, no need to put in the beefier wire.

 

[gregd]

If you are thinking you might want 100 amp circuit (80 amp charging on one or two hpwc), but you intend to start with a 50 amp circuit (40 amp charging), then the electrician could size the wire for 100 amp (around 3 gauge, depending on the run) but install a 50 amp breaker and 50 amp plug. Everything is properly protected this way. Then, in the future, you can have the electrician come back and install the HPWC and change the breaker to 100amp.

This is what I did, but used #4 wire. It's the largest wire that the 14-50 outlet would accept. That will limit future upgrades slightly, but still plenty of headroom for almost any situation.

 

[AndrewTX]

Well, we're gonna pull the trigger on a Model S this fall! Not sure what options it will have, but I'm looking at CPO cars.


Can you guys check my math here? I'm leaning at a simple 14-50 (240v) outlet and the UMC. Gotta be AC...right? Should come off a 50A breaker, or maybe 2 for 100A and my box needs to be able to handle the juice? Hopefully he'll know those limits. Can we do a 100A to the 14-50 for a later upgrade to a HPWC?



I appreciate any insights or advice that I need to consider and discuss with the electrician.

Buster

You strategy depends almost entirely on your expected daily usage. With a NEMA 14-50 outlet you can charge at 28 miles/hour. How often do you really expect to need to charge faster than that? I've learned that I never need to do so.
When I had to make this decision I leaned toward getting an HPWC with an 80A circuit. My electrician(Tesla recommended and experienced) talked me out of it and I am glad he did. I've never had the need for anything beyond the NEMA 15-50/UMC combo and it saved me a good amount of money.

 

[johnnyS]

In almost 5 years of owning a model S, our 50 amp breaker to a 14-50 outlet providing 40 amps at 240V has always been adequate.

 

[Buster1]

Thanks guys! I just met with my electrician and we came up with a great plan for a 14-50 and some 6 ga wires and conduit! The electrical box is adequate and actually has an old 240 breaker for an old hot tub that's long gone. We're gonna replace that breaker and start bending conduit soon! Should be a simple run inside the garage to a location where the future Tesla will sleep.

Thanks for the advice guys!

 

[scottm]

Well, that was easy then.

Sounds like a perfectly adequate solution for home charging.