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To upgrade panel from 100 to 200 amps or not.

LCR1

Active Member
Oct 24, 2017
1,332
980
Houston
I'd have a 14-50 installed at a minimum, that load estimate included everything at max load. You're most likely charging while you're asleep every night and mine starts around 1AM if you charge at 32A on the 14-50 with your mobile connector that's 2-3 hours to refill your daily commute so you're still asleep. What's on in your house at 1AM? The A/C is probably it, water heater (if electric) should have cycled off by 1am after any showers. I'd have no problems running a 14-50 and using the included mobile connector.
 
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LCR1

Active Member
Oct 24, 2017
1,332
980
Houston
How can you not calculate everything you use? It's quite easy to have both A/Cs or both Heaters running, stove, water heater, lights, TV and cars charging. That alone can put me over 140amps easy. Then lets count everything else plugged in and in use, if someone made a load calculation without calculating everything then it wasn't done properly.
 

davewill

Active Member
Feb 5, 2014
1,825
1,975
San Diego, CA, US
Different appliances have different duty cycles. Heaters run at different times as AC. Air conditioners and electric motors need extra current when starting up. Other appliances cycle on and off or up and down. You have many 15a circuits but most of them will never have a 15a load on them. EVs are actually unusual in drawing their max amount for an extended period. All of that is figured into a load calculation. If you just add up the max rating of every appliance it may well exceed your main feed. Anyway, if a qualified electrician did a proper load calc and says there's only room for a 30a circuit, there probably really is only room for a 30a circuit.
 
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LCR1

Active Member
Oct 24, 2017
1,332
980
Houston
Which is why I said both heaters or both ACs, either of which run continuously for extended periods of time, the same with every other thing I listed. So if I had a 100A service I would have blow the load anytime those things are on. If the electrician didn't do a load plan for these things to be running at the same time, my max load on the house would have been completely under estimated and i'd have a useless 100A panel.
 

dhrivnak

Active Member
Jan 8, 2011
4,436
3,651
NE Tennessee
I know the 30 Amps should be more than sufficient for my use. I'm more so concerned about maxing out the panel load by adding the 30 Amps than by the charging rate. But I'm not sure if its a valid concern.
No that should not be a problem BUT if you have plans or thoughts of a second plugin I would bite the bullet now.
 

davewill

Active Member
Feb 5, 2014
1,825
1,975
San Diego, CA, US
Which is why I said both heaters or both ACs, either of which run continuously for extended periods of time, the same with every other thing I listed. So if I had a 100A service I would have blow the load anytime those things are on. If the electrician didn't do a load plan for these things to be running at the same time, my max load on the house would have been completely under estimated and i'd have a useless 100A panel.
So which is it? The electrician is overestimating and he actually needs a bigger panel, or the electrician is underestimating and he should just put in the 50a circuit and not worry? You've managed to say both.

OP, just listen to your professional and stick with 30a or upgrade the panel.
 
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SBarnes

Member
Dec 15, 2015
11
22
Grand Terrace, CA
The "load calcs" the electricians use are not precise, they are more like a rule of thumb. As others have mentioned they just make a general estimate based on what you equipment you have in your home. For example a pool pump will add a certain number of amps, they don't actually go out and look at your pool pump and see what its actual draw is and how you use it. We got multiple quotes, one electrician's load calc came out just under 100 amps, another 1 amp over. I ended up not upgrading the panel, after everything was installed to test I started charging at max current (40 amps), then turned on my AC, all the lights in the house, the pool pump, the microwave, and anything else I could find. My 100amp breaker did not flip everything was fine. I suspect part of the reason is the load calc probably assumes incandescent lighting still, I have all LED which is about 1/10 the amperage. As long as your panel is in good condition, worst case scenario is your main breaker flips and you find out you can't charge your car and run your AC at the same time. And for those that say "no, worst case is your house burning down and everyone dies": a) I think you are putting to much faith in the precision of "load calcs" and b) that would require some faulty equipment (as your main breaker will prevent more then 100 amp draw, and the panel by definition can handle 100 amps), and if you are presupposing faulty equipment then fire and death is always the worst case scenario no matter what you do.
 

LCR1

Active Member
Oct 24, 2017
1,332
980
Houston
So which is it? The electrician is overestimating and he actually needs a bigger panel, or the electrician is underestimating and he should just put in the 50a circuit and not worry? You've managed to say both.

OP, just listen to your professional and stick with 30a or upgrade the panel.

It's exactly what I said. In the OPs case the 69 amp should have been the max load with things like AC, stove, water heater, normal TV light use, etc, etc. That is 69 amps and that is the max load he should see on a daily basis. However the OP isn't drying clothes, taking a shower, and/or cooking at 1AM. Therefore, if he charges the car when the house isn't at max load like 1 or 2am the calculated max load is irrelevant for that time period and OP can install a 14-50 and charge the car at max amperage.

If the OP decides to charge in the middle of the day when the house is likely to experience max load then simply reduce reduce household usage or reduce the amperage manually in the car.

If the OP decides they want to charge at max house load in the middle of the day and with the max car load then yes, spend thousands to have new service cable run for a 200A panel and they can do that worry free, or they can simply shift the load of the car to off peak of the house and continue with a 14-50 and enjoy their saved thousands.
 
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Need

Active Member
Nov 22, 2017
2,912
2,209
SoCal
It's exactly what I said. In the OPs case the 69 amp should have been the max load with things like AC, stove, water heater, normal TV light use, etc, etc. That is 69 amps and that is the max load he should see on a daily basis. However the OP isn't drying clothes, taking a shower, and/or cooking at 1AM. Therefore, if he charges the car when the house isn't at max load like 1 or 2am the calculated max load is irrelevant for that time period and OP can install a 14-50 and charge the car at max amperage.

If the OP decides to charge in the middle of the day when the house is likely to experience max load then simply reduce reduce household usage or reduce the amperage manually in the car.

If the OP decides they want to charge at max house load in the middle of the day and with the max car load then yes, spend thousands to have new service cable run for a 200A panel and they can do that worry free, or they can simply shift the load of the car to off peak of the house and continue with a 14-50 and enjoy their saved thousands.

That's actually the same thing our electrician asked us when we installed our NEMA 14-50. He asked that how likely are we to use the double electric oven at the same time as we are charging the car. I told him highly unlikely, unless a burglar breaks into our house in the middle of the night and decided to bake himself a cake. You see we don't really use the oven much let alone in the middle of the night at super off peak hours for charging.
 

LCR1

Active Member
Oct 24, 2017
1,332
980
Houston
That's actually the same thing our electrician asked us when we installed our NEMA 14-50. He asked that how likely are we to use the double electric oven at the same time as we are charging the car. I told him highly unlikely, unless a burglar breaks into our house in the middle of the night and decided to bake himself a cake. You see we don't really use the oven much let alone in the middle of the night at super off peak hours for charging.

Precisely what I do, my home has a 200A main panel and 2- 100A subpanels, I've probably got 400A+ of breakers wired into all the panels but I don't use them all at once. Everything in my home is electric, I have 2 separate HVAC systems, 2 separate kitchens, 2 separate laundry rooms, etc (although 1 water heater) but the well is electric (obviously)

The most that is running around 2Am when the car charges is the ACs pulling 30-40amps the fridges and deep freezers cycling maybe? But plug in the Leaf and S at 2pm in a Texas summer, while doing clothes and cooking? Well I'm not going to try it.



I am waiting to be "corrected" by a statement like "you can't charge the car at max amps with 14-50 because 14-50's only rated at 40A continuous and the car can pull 48A" :rolleyes:


When I was in the OPs spot I simply Installed the 14-50 because it was the cheapest and easiest and allow expansion to everything but the biggest need for an EV. The car charges full in a few hours (easily from dead to 90% overnight) and even gives me enough in 1 or 2 hours if I feel I need more range mid-day
 
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pikachu

Member
Feb 15, 2016
66
103
SF East Bay, CA
OP, you said the wiring doesn't have to travel very far from the panel. What is "not very far"? The price you listed seems like you are going 100' out or more. Also if you are getting more quote, don't tell them it is for a Tesla. When I installed our NEMA 14-50, I told them it was for an EV car.

It would be about 20ft at the max. I've tried to be non-committal with the other electricians I've talked to and just mentioned a Nema 14-30 but I most likely want to install a Tesla wall connector so may have to disclose at some point if I want an accurate quote.
 

pikachu

Member
Feb 15, 2016
66
103
SF East Bay, CA
hey don't actually go out and look at your pool pump and see what its actual draw is and how you use it.

This electrician actually went out to look at our A/c and all the other major appliances in the house to see the draw. But I do understand what you are saying. I highly doubt we will be running anything other than the A/c in the summer at the time the car is charging.
 

pikachu

Member
Feb 15, 2016
66
103
SF East Bay, CA
When I was in the OPs spot I simply Installed the 14-50 because it was the cheapest and easiest and allow expansion to everything but the biggest need for an EV.

My city does require a permit for this. I'm not sure if we will be able to install a circuit that would exceed the electrical load of the panel even though logically it should not be overloaded at the time the car is charging. But it's something for me to explore. Thanks for the idea!
 

pikachu

Member
Feb 15, 2016
66
103
SF East Bay, CA
I asked the same electrician (Tesla recommended) for a ballpark estimate on upgrading the panel from 100 to 200 Amps assuming we add a second EV down the road. He said "Unfortunately, upgrading your homes electrical system would prove to be a very costly and time consuming project. Your PG&E electrical service comes in from underground, which makes the job so difficult. A quick ballpark estimate of a job of this scope could easily run you anywhere from $10,000-20,000 and take over 6+ months of coordination with PG&E." :eek::eek::eek:

Obviously, I've lined up a few other (non Tesla recommended) electricians over the next few days to get more quotes. But if there's any indication at all that the upgrade would be even half of that ballpark, we'd just go with the 30 Amps and call it done.
 

LCR1

Active Member
Oct 24, 2017
1,332
980
Houston
The number of breakers in a panel and their added amperage are irrelevant. One of the 10x10 bedrooms in my house for what ever reason has 7 outlets all in different circuits. That's 7x15= 105A. The two ACs are in 30A each, water heater is 30A, main dryer is 30A and stove is 50A, well is 20A that's 190A of breakers before you even count a single outlet or light. Then you have 2- 100A breakers going to sub panels for everything else. I'll actually count them up tomorrow cause I'm curious now.

Point is even pulling permits and inspections there's no reason you can't install a 14-50 now instead of the 14-30 you're asking about now. The outlet is the same cost. The breaker is about 20-$30 more and the wiring from 10 to 6ga is about 0.75-$1/ft more for romex style. If using THHN or THHN2 you only need 8ga

If you're eventually going hpwc in the future you have a few options:

continue using the hpwc with the wife from the 14-50 and set the limiter to 40a continuous or what ever it is inside the unit.

Run the biggest wiring now you can fit into a 14-50 outlet so later on you can simply remove the outlet/ breaker combo and install the HPWC. 3ga THHN will get you a 100amp circuit to max out the hpwc

Install the 14-50 then have them come back and install the hpwc from scratch

You can have them run both wiring for 14-50 and HPWC but not connet the HPWC to anything (just close it off in a junction box on the wall with no breaker) then when the time comes you can install the hpwc, and still have the 14-50 for something else. More up front but more lifetime usability should also only require pulling the permit once, connecting a breaker and shoving the wires into the hpwc in 3 years shouldn't require another permit( no different than wiring in a new light to an existing circuit)

The problem I see is you're limited to 100 amps at the panel so maxing out a wall charger with 80 amps, I wouldn't even do because 20 amps isn't a lot of room if the AC comes on with something else at night.

If all you're ever going to charge is the M3 at 48 amps go for it. Have them hook up the 14-50 with #4 romex or #6 THHN and that will get you a 60A circuit capacity when you switch out for the wall charger. So you charge at 32/40A with the mobile charger on the 14-50 and the full 48 when you install the HPWC and you could also split 2 in the future at 24A if you daisy chain them.
 

tpabeav

New Member
Jan 30, 2018
2
2
Tampa
Hi folks, I configured in the batch of invites that went out on Feb 22 and I'm finally getting around to figuring out the charging solution at home. Got the first quote from a Tesla recommended electrician here in the Bay Area and looks like our electrical load is 69.5 Amps out of the available 100. That leaves us with about 30 Amps. Breaker would be installed in the panel in the garage. Wiring should be pretty straight forward and doesn't have to travel very far to the install spot. Quote below:

1. Install a NEMA 14-30 receptacle on a 30 Amp circuit. Provides 24 amps for charging. Electrician says the car would charge at ~ 22 miles an hour.
Estimated cost - $ 1240

2. Install Tesla wall connector on a 30 Amp circuit. Same charging rate as above.
Estimated cost - $ 1940

Permits and fees - Additional $550

Firstly, the cost seems excessive for what would seem to be a simple install if we go with Option 1. I'm chalking this up to 'Tesla recommended' premium and will get more quotes.

I commute 70 miles a day and although the 30 Amps would be enough to wake up to a full battery based on the charge rate above, I would like to take advantage of the car's higher charging capacity. But what surprises me is that he didn't recommend we upgrade our panel to 200 Amps at all. Does it make any sense to max out current panel in terms of load close to a 100%? Should we even consider not upgrading the panel? (Would make the husband happy :p) Would appreciate any input. TIA!


It may be different in my area, in Florida I was lucky enough to have been able to install a 100 amp 220 breaker and run new conduit in the garage for around $500. Plan B was to put a sub panel with the 100 amp 220 volt with conduit for $600.

Total cost for Tesla wall charger ($500) plus 100 amp install was around $1,000 for everything including the wall charger.

I think this should give me up to 70-80 amps to charge.

I also ran the max 100 amp in case my wife wants the model Y and I put 2 wall chargers in. You need the 100 amp to dual balance charge.
 

jbcarioca

Well-Known Member
Feb 3, 2015
5,258
25,639
Probably I would upgrade the panel were I planning to keep the house. That would be to future-proof the house electrical supply.
For home charging I have had 208/24 amps for more than three years. I can consistently charge to 100% overnight if I am expecting a long trip. Otherwise I usually charge to 80% or so for trips <100 miles. It is tempting to install more power, after all more is better! However, I have never once actually needed quicker charging. For anything larger there are more and more superchargers and local charging options. Admittedly in your area there can be crowded. Still, anything about 220/30 is overkill at home except in rare cases. A rare case I know of might be a couple who commute 150 miles every day...and they have 208/30 just as I do.
 

SBarnes

Member
Dec 15, 2015
11
22
Grand Terrace, CA
As others have said you won't have any problem charging overnight. About twice a year I do wish I had faster charging, either we forget to range charge the night before a trip (so we get up realize it and start trying to charge the car quickly in the morning), or one of us returns from work and we try to quickly top off the car before we leave on a trip that night. For us that happens about twice a year, the first situation is obviously preventable, the second one you just have to deal with.
 

brkaus

Well-Known Member
Jul 8, 2014
7,739
6,273
Austin, TX
A quick ballpark estimate of a job of this scope could easily run you anywhere from $10,000-20,000 and take over 6+ months of coordination with PG&E."
I was given a similar estimate to upgrade 200A to 400A. Needed to put in larger conduit back to the transformer and dig up my driveway. Quote did not include replacing the aggregate concrete drive. I decided I'll live with 200A. I do have a large house - 3 HVAC, 2 ovens, 2 dishwashers, electric dryer...
 

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