Building a house - what to install?

[tga]

You also didn't say whether you plan to install solar panels. Many permitting authorities stupidly limit solar input to 20% of panel rated capacity. On a 200A panel, that would limit you to 9.6 kW of solar. The difference in cost between a 200A panel and 400A panel is only about $500, so you might want to build in room for solar even if you won't install it right away.

That's an NEC requirement - 705.12(D)(2), but it only applies when backfeeding through a breaker into the panel. You can get around it with a supply-side connection.

To the OP's question, if you aren't sheetrocking the garage, just have a 100A (or even 125A) subpanel installed, and worry about the rest later.

 

[gavine]

I dont believe any benefit of having PowerWalls installed.

What about powering your house during a grid outage? The PowerWall provides that and enables use of your solar panels during an outage as well. Without Powerwall, your solar system shuts down during an outage.

 

[Boourns]

Going to bump this thread because I am in the same situation, and I'd like to get the group input.

I told the builder that, ideally, I'd like a 200A subpanel dedicated to EV charging. This would allow two HWPC to charge at 72 amps at the same time, right? I have an S now and a 3 on the way.

 

[gavine]

Going to bump this thread because I am in the same situation, and I'd like to get the group input.

I told the builder that, ideally, I'd like a 200A subpanel dedicated to EV charging. This would allow two HWPC to charge at 72 amps at the same time, right? I have an S now and a 3 on the way.

Unless you plan on charging both cars simultaneously at 80A each, I would say 200A dedicated to charging is overkill. At home, you can get away easily with 50A charging so, to me, 100A is more than enough. Also, the new HPWC's can be networked together to share the load so, if you don't necessarily need to charge both cars at full tilt simultaneously, you might even get away with a shared 50A circuit. With that, both cars can charge at 15MPH/ea. simultaneously, or 30MPH alone.

 

[Boourns]

Excellent points, @gavine. Thanks.

 

[BrokerDon]

If you are building a new house, there is no reason not to have a panel big enough to support a 100A circuit for EV charging (check with your utility to be sure the supply to your new house is capable of supporting a big panel). Then you need wiring installed sufficient for a 100A circuit to the charging location - within 15 feet of the left rear of your car (I know the cables are longer, but you need slack to reach down to the floor without making a tripping hazard).

Yes, you can get by with just a 50A outlet (NEMA 14-50) for charging M3, but what will the charging capacities be on future EVs that you might own? If you are wired for 100A, you can easily downgrade to 50A breaker and outlet, but you couldn't easily upgrade from 50A wiring to 100A.

Are you likely ever to have two EVs? You might want to have panel capacity and wiring pulled for a second EV charger.

You also didn't say whether you plan to install solar panels. Many permitting authorities stupidly limit solar input to 20% of panel rated capacity. On a 200A panel, that would limit you to 9.6 kW of solar. The difference in cost between a 200A panel and 400A panel is only about $500, so you might want to build in room for solar even if you won't install it right away.

Also, make sure that your contractor will not skimp on wiring. I have seen many houses where they installed 14AWG wire for convenience outlet circuits (instead of the customary 12AWG 20A circuits), limiting the whole circuit to only 15A, which is not enough for a floor heater and hair dryer to operate at the same time. Since two or three bathrooms are often wired on the same circuit, hair dryers in two bathrooms at once could trip a 15A breaker.

Absolutely AWESOME advice! Our 2007 built 2,850 sq. ft. tract home was built with a 200 amp main service panel + 100 amp subpanel using every breaker space in both panels. To legally add an outdoor kitchen, a 30 amp / 120V RV outlet, and Tesla Gen1 High Power Wall Charger we had to eliminate the electric dryer outlet (not a problem since we had a gas dryer anyway) but also had to "double up" every possible breaker with a "load calc", Now our 200A main and 100A subpanels are completely full. Adding solar will require us an expensive upgrade of our just 9 year old 200A main service panel to a 225A "solar ready" panel or a 400A panel.

Also consider installing a whole house surge suppressor in your main service panel. They're fairly inexpensive especially when installed in new construction and will probably save one or more of your electronics or appliances from a premature failure.

You may also want to install multiple 20A duplex outlets spaced apart at any location where you'll have HDTVs or home theatre... including some at eye level where you're wall mounted HDTVs will be located.

Think about having your entire home run with Cat 5e or 6 Ethernet cable "home run" to a central wiring closet for computers, WiFi access points (wired "range extenders, security / baby cameras, smart HDTVs / Bluray players, DVRs (cable boxes / TiVos), printers, etc. Yes a lot of these can be wireless but wired is SO much more reliable and easier to troubleshoot. I'd also run at least 3 Ethernet cables your garage: one for a WiFi access point Tesla WiFi is very limited range, ... and another to your main service panel for a solar inverter's monitoring data. You're better off running more data and power cable than you need than having to go inside walls & ceilings to add them later. Make your electrician & data cabling contractors run their cables neatly inside wiring "runs" with spare conduits to easily add more in the future.

Finally insist in writing that all your contractors keep their wiring, ducts, etc. out of the way in attics so you can have clear access to add wiring, insulation, lighting, fans, etc. later without having to be a contortionist... and have them install a catwalk for future access. A couple of sheets of plywood now will make a world of difference when you need attic access.

 

[Yarder]

And add 120 outlets under the exterior eves of the house to conveniently plug in your Christmas light strings.

 

[BrokerDon]

And add 120 outlets under the exterior eves of the house to conveniently plug in your Christmas light strings.

Or leave them up all year and call them "Party Lights" LOL

 

[Boourns]

Just to update in case anyone cares, I talked to the builder (rather than the sales person) yesterday. He said that a 200A subpanel and wiring will cost about $2,700. He can do a 125A subpanel and wiring for about $1300. Trying to decide if the extra $1400 is worth having the ultimate future proofing. On one hand, as a percentage of the cost of the house, why not. On the other, it does seem excessive, especially since my current S doesn't have dual chargers. Luckily I have a month or two to think it through.

 

[Lasttoy]

I was told at service center my dual chargers only work if I have a 100 amp circuit for the car. That is $5000, need new feed from pole on street. My house only has 100amp for entire house now. I was in shock. Who knows this before they buy a second chargers??
My electricians installed a 40 amp, 14.50 receptacle.

 

[miimura]

Just to update in case anyone cares, I talked to the builder (rather than the sales person) yesterday. He said that a 200A subpanel and wiring will cost about $2,700. He can do a 125A subpanel and wiring for about $1300. Trying to decide if the extra $1400 is worth having the ultimate future proofing. On one hand, as a percentage of the cost of the house, why not. On the other, it does seem excessive, especially since my current S doesn't have dual chargers. Luckily I have a month or two to think it through.

Personally, I would spec the 125A panel and 100A wiring in the walls to two different charging station locations in the garage. Initially install 50A breakers and 14-50 sockets, or leave them unterminated. With the 100A wiring in the walls, you could install full capability shared-load Wall Connectors in the future. Personally, I did 50A home runs to the main panel on each side wall of the garage 5 years ago. However, if I was doing it today, I would do the sub-panel.

 

[Rocky_H]

I was told at service center my dual chargers only work if I have a 100 amp circuit for the car. That is $5000, need new feed from pole on street. My house only has 100amp for entire house now. I was in shock. Who knows this before they buy a second chargers??
My electricians installed a 40 amp, 14.50 receptacle.

I guess I am wondering why would someone not know that? What did you think the second charger is for?

I actually don't see any good reason to have really high power charging at home. You have all night to recharge. But the dual charger in the car has some value in itself while you are traveling away from home in some areas that are a bit too far away from Superchargers and have some high amp wall connectors in some places.

 

[BrokerDon]

Our inventory P85D came with dual chargers and a Gen 1 Tesla High Power Wall Charger. After multiple road trips over 21 months we have rarely found destination chargers, including Tesla High Power Wall Chargers, to exceed 40A so I wouldn't get dual chargers for destination charging.

At home we charge our Tesla a. 60A / 240V using our HPWC because we had dual chargers... and could install a 100A circuit for out HPWC to run u[ to 80A. We only charge at 60A though to keep the HPWC & Tesla charge port cooler to help it last longer (they both get very warm charging at 80A)

Biggest benefit of having a HPWC at home is never having to deploy & restore your Tesla UMC... so you can just leave it in your Tesla trunk... and never accidentally forget it.

 

[arnis]

Exactly! Mobile EVSE should just be in the vehicle and not used daily. That is actually recommended.

BTW, most likely, it is not the male-female connection that warms up at high charging rate (80A).
It's most likely the cable and cable to plug pins inside the handle.
At SC current is multiple times higher, temperatures on the other hand do not skyrocket.
If you have Ir thermometer you could measure cable, end of the cable near plug and the plug handle
temperature at 80A current. Or just use regular thermometer and tape the sensor to the cable.
You should see that cable itself is warm and cable near the plug is even warmer. That's my theory

 

[BrokerDon]

Exactly! Mobile EVSE should just be in the vehicle and not used daily. That is actually recommended.

BTW, most likely, it is not the male-female connection that warms up at high charging rate (80A).
It's most likely the cable and cable to plug pins inside the handle.
At SC current is multiple times higher, temperatures on the other hand do not skyrocket.
If you have Ir thermometer you could measure cable, end of the cable near plug and the plug handle
temperature at 80A current. Or just use regular thermometer and tape the sensor to the cable.
You should see that cable itself is warm and cable near the plug is even warmer. That's my theory

I think your correct. The original Gen1 HPWC I received was an "Open Box" (long story why it wasn't new)... and got crazy HOT at 80A. Tesla sent a Ranger to our house the following day with a replacement cable that fixed the HPWC overheating problem.

Now our Gen1 HPWC plug gets warm (not hot like it did before) at 80A... so we charge at 60A to put less thermal stress the HPWC plug, Tesla charge socket, and dual chargers since from my experience heat is the #1 killer of electronics.

Also, I occasionally use a can of WD-40 300083 Specialist Electrical Contact Cleaner Spray Amazon.com: WD-40 Specialist Electrical Contact Cleaner Spray - Electronic & Electrical Equipment Cleaner. 11 oz. (Pack of 1): Industrial & Scientific to keep our HPWC plug and Tesla charging socket contacts clean.

YMMV

 

[Craig-Tx]

Personally, I would spec the 125A panel and 100A wiring in the walls to two different charging station locations in the garage. Initially install 50A breakers and 14-50 sockets, or leave them unterminated. With the 100A wiring in the walls, you could install full capability shared-load Wall Connectors in the future. Personally, I did 50A home runs to the main panel on each side wall of the garage 5 years ago. However, if I was doing it today, I would do the sub-panel.

While there, run a data cable between the two potential HPWC locations, unless it will be easy to run in the future.
IIRC, the HPWC specs out a 18 AWG shielded twisted pair cable to go between the multiple HPWCs.