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100A Main Panel Question

Gauss Guzzler

Member
Dec 27, 2020
453
561
Thousand Oaks, California
Lotta tangents in this thread. Your 100A panel is fine as long as it's possible/legal to add one more double pole breaker. Anything from 20A to 60A will be fine with your wall charger. If your electrician insists that your life will be better with a new panel just ask to see the load calculations and NEC code regulations because chances are, it won't.
 
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JackLuminous

Member
Apr 29, 2021
86
45
Northern Virginia
Why do you think you need a 40 amp circuit. A NEMA 1430 ( 30 amp) would be more than enough to recharge the car overnight.

Getting a 14-30 installed in 2 weeks. Electrician's load calculations advised against 14-50 and said if I wanted to proceed, then they could add a $1500 switching thingy (WTH). A previous electrician didn't think there would be any problem with a new 50amp breaker in a 100amp panel...
 
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Sorny

Member
Jun 2, 2021
60
78
MN
Installed a 40A breaker in my 100A main panel and ran 6ga to the Gen3 wall connector about 2 weeks ago. But, I've got all gas appliances, and despite the panel having only 4 slots open total, I'm confident I won't be over capacity since the highest load other than the wall connector is the central air, and that's on a 30A breaker.

I probably could have thrown a 50A or 60A breaker in the box and been fine, but I'm confident in my decision to only put in a 40A breaker at this time; how much faster do I really need to be able to charge the car?. Besides, should I ever decide to upgrade the service to the house, I can simply pop out the 40A and replace with a 60A; but that is a couple thousand dollars I don't want to spend at this time (upgrading service to the house from 100A to 200A).
 

context

Member
May 27, 2021
8
4
Oregon
Personally I would install a 50 amp circuit. If you find your main breaker tripping you can always reduce the amps using the Tesla app, but if you schedule to charge at night while your sleeping and presumably not using your range/dryer etc you will be fine.
 

Rocky_H

Well-Known Member
Feb 19, 2015
6,660
7,953
Boise, ID
Personally I would install a 50 amp circuit.
If load calculations allow, then sure, someone could start with this.
If you find your main breaker tripping you can always reduce the amps using the Tesla app,
But no, that is not an appropriate solution. If you are pushing that much to the edge of capacity that you are getting actual breaker trips, you do not deal with that with a software setting. That should be changed to a lower capacity circuit.
 
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Braumin

Member
Mar 5, 2021
54
53
Canada
I was in the same scenario. 100A panel. Lots of breaker space available but not a lot of current capacity available. I got a permit and installed a NEMA 14-30 with (hopefully obviously) a 30A 2-pole breaker.

With a 100A panel you are limited to 80% of the max capacity of your main breaker, which means 19,200 watts total draw. You have to do a load calculation based on your square footage of your house as well as what appliances you have now. If you aren't comfortable doing that, you really should call a pro IMHO. My load worked out to 18,000 watts with the 30A breaker. A 50A would have been too much.

Everyone on this forum will tell you go with the 50A if you can, and while they aren't wrong, it's likely more than you will need for daily driving. I was charging on 115V 15A for the last three months until I got the new circuit fired up. Unless I went on a road trip, it was fine. With 240V 30A I can recharge overnight basically in any situation. 50A would be nice, but I didn't have room in the panel, and 30A is plenty.

Just because the Tesla can be set manually to charge at a reduced amperage doesn't make it right to put a circuit too big for your panel in. It would be against code, you could possibly have insurance issues if there ever was a problem, and you can't guarantee what will be plugged into that circuit in the future. Maybe someone will plug in a welder or something.
 

JackLuminous

Member
Apr 29, 2021
86
45
Northern Virginia
I was in the same scenario. 100A panel. Lots of breaker space available but not a lot of current capacity available. I got a permit and installed a NEMA 14-30 with (hopefully obviously) a 30A 2-pole breaker.

With a 100A panel you are limited to 80% of the max capacity of your main breaker, which means 19,200 watts total draw. You have to do a load calculation based on your square footage of your house as well as what appliances you have now. If you aren't comfortable doing that, you really should call a pro IMHO. My load worked out to 18,000 watts with the 30A breaker. A 50A would have been too much.

Everyone on this forum will tell you go with the 50A if you can, and while they aren't wrong, it's likely more than you will need for daily driving. I was charging on 115V 15A for the last three months until I got the new circuit fired up. Unless I went on a road trip, it was fine. With 240V 30A I can recharge overnight basically in any situation. 50A would be nice, but I didn't have room in the panel, and 30A is plenty.

Just because the Tesla can be set manually to charge at a reduced amperage doesn't make it right to put a circuit too big for your panel in. It would be against code, you could possibly have insurance issues if there ever was a problem, and you can't guarantee what will be plugged into that circuit in the future. Maybe someone will plug in a welder or something.
100% agree. 14-30 installed last week has worked well. We're able to top back to 80% overnight once we've hit 50% SoC -takes about 5 hours. This is perfect for our needs. If we need to do a road-trip, we'll use a Supercharger.
 
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abhikbhatia

Member
Jun 7, 2021
27
44
Sacramento, California
Interestingly enough, my electrician came out and checked our panel.

House is built in the 80's and the panel is really old. Poses as a fire risk. They told us that our home insurance should be able to cover the cost to upgrade it to 200A panel so we started a claim.

Our insurance accepted and is fully covering the cost of upgrading our panel.

If anyone else has an older house, definitely worth looking into if your home insurance can cover it as it did for us!

For reference, our house has the Zinsco panel. They're upgrading us to something more modern.
 

Braumin

Member
Mar 5, 2021
54
53
Canada
Interestingly enough, my electrician came out and checked our panel.

House is built in the 80's and the panel is really old. Poses as a fire risk. They told us that our home insurance should be able to cover the cost to upgrade it to 200A panel so we started a claim.

Our insurance accepted and is fully covering the cost of upgrading our panel.

If anyone else has an older house, definitely worth looking into if your home insurance can cover it as it did for us!

For reference, our house has the Zinsco panel. They're upgrading us to something more modern.
Wow that is nice. I guess it makes a lot of sense for them to want to avoid that claim.
 

JackLuminous

Member
Apr 29, 2021
86
45
Northern Virginia
Interestingly enough, my electrician came out and checked our panel.

House is built in the 80's and the panel is really old. Poses as a fire risk. They told us that our home insurance should be able to cover the cost to upgrade it to 200A panel so we started a claim.

Our insurance accepted and is fully covering the cost of upgrading our panel.

If anyone else has an older house, definitely worth looking into if your home insurance can cover it as it did for us!

For reference, our house has the Zinsco panel. They're upgrading us to something more modern
Niiice! Much cheaper for ins company than if they had to deal with the alternative.
 

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