Is it two 100 AMP breakers with the switches interconnected. I have no idea what is going on inside this box on the outside wall which is connected to the A/C and panel in the garage.
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Is a dedicated circuit breaker required for a HPWC installation
- Thread starter jboy210
- Start date
Is it two 100 AMP breakers with the switches interconnected. I have no idea what is going on inside this box on the outside wall which is connected to the A/C and panel in the garage.
That would be 100a. There is a breaker on each leg. It would still trip if either leg exceeded 100a.
Thanks. I will check with the electricians and see what they can find out. I assume the 50 Amp breaker out by the compressor implies that 50 Amps is all that it can use. Is that correct?
You have 100 amp service. Given you mentioned heated floors in an earlier post, you are probably looking at a 200 amp upgrade to run a circuit for your car.
It is possible to run a 40 amp max circuit (50 amp breaker) from a 100 amp panel, but it is really tight. If you have no other large power draws it might be possible (I did it). But I eventually caved and upgraded my panel to 200 amps. Besides the new larger panel, it also required a new meter base, meter, and larger weatherhead into my house. All completed for about $3600. The only thing I did not need was a new drop from the utility. The power company upgraded all their customers to lines adequate for at least 200 amps, several years ago.
Don't I already have 200 Amps to the house? As I mentioned there is a secondary breaker box next to the power meter that has 2 - 100 Amp breaker?.
No, it is not. That 100A breakers with interconnection means you have 100A service. Each service line comes with 2 hot wires, 100A/120V each (100A 240V available). That’s why you see two breaker.
Service rating is the 240V amperage (both hots). Each leg only has 100 Amp breaker, so a 240V load can only pull 100 Amps. You could pull 200 Amps of 120V load, but that is not 200 Amp serivce.
GHammer
Dark Star
Ok. So I guess I need to have service from the street upgraded also? This should be cheap.
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Maybe, maybe not. If you are getting quotes from electrical contractors, they will be able to tell you what you need to do. In fact they will coordinate all activities with your utility including necessary permits. (If they don’t, pick somebody else)
Thanks for the suggestion. My goal was to get to 240/50, but we will see what the city and electrical contractor can get us.
I think the saying is perfect is the enemy of good. I would look at all options before spending a few grand on charging.
Of course, if upgrading, I’d go all in.
But if I could come up with a cheap solution to gain experience and buy time safely, I would go with that. I think you said there was an outlet in the garage that is no longer connected. If that could be landed on a 30 or 20a breaker and appropriate outlet installed... it should be pretty cheap.
Now, with that said, if you drive 200 miles a day... 20a is not going to get you very far.
The concern is we may be getting a second Tesla (or other EV) so then charging time become an issue and/or expansion to a second charger. Since we are going though all this work I want to ensure we have options that work today, and in the future without have to tear up walls and ceilings, again.
I would recommend you to look into a solar system solution. I think you have the same situation with me in the past.
+ My service was 100A before. Decided to install 240V-50A circuit into the current panel. Converted 4 x 20A circuits into 2 tandem breakers. I only charged the car after 10pm & didn't use AC at night. So 100A is safe. If I need to charge the car while AC is running, I set the max charge output to 16A.
+ Lately, I bought a second Tesla. Realized that I need another charger as I couldn't swap the charge at night. Also, my electric bill went crazy.
+ Went solar. Can charge my car at anytime I want. Monthly cost for the solar loan is just 1/3 of electric bill. Tesla covered all electrical panel upgrade to 200A, bigger line hanging & lot of stuff required by my local inspector for $1750. Would be t least 2 times higher if I hire an electrician directly.
That is definitely something we want to look in to. We were hoping Tesla would have their Solar Spanish or wood shake look roof by now.
But, the biggest issue for us is the massive trees (I have a picture of 5 guys in one at the same time trimming) we have in the southern part of our yard and that shade the roof. According to Google Solar map app we only have about 150 square foot of roof that gets decent sun. Would that be enough?
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FWIW, the Tesla HPWC (or WC) can be paired such that they share a total current limit.
Update.
Electricians were just here. They did load calculations and looks like we can get up to 50 Amps to HPWC. I think this should be enough for our low usage (40-60 miles/day). Turns out the panel can support the new thinner breakers so we have about 12 open breaker slots. There also had a nice idea for mounting the HPWC on the post and hiding all the wiring in a false cavity. Estimate to install is $600 including permits, etc. Work starts in a couple of weeks.
Electricians were just here. They did load calculations and looks like we can get up to 50 Amps to HPWC. I think this should be enough for our low usage (40-60 miles/day). Turns out the panel can support the new thinner breakers so we have about 12 open breaker slots. There also had a nice idea for mounting the HPWC on the post and hiding all the wiring in a false cavity. Estimate to install is $600 including permits, etc. Work starts in a couple of weeks.
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