Rough Power Situation - Should I upgrade? Electric advice sought

[sooner]

Presently, I live in a very small home, built in the 1970s.
Unfortunately, this home only has a 100amp breaker box. On that box there is a switched off breaker for a 30amp outlet that used to be an in-wall air conditioner. Now the current air conditioning system is outside, and does not have a dedicated breaker. Normal home things, washer, drier, natural gas furnace, natural gas water heater, air conditioner, stove, microwave, and two powerful PCs are they extent of my heavy appliances.

I say presently because ideally I will be building a house starting next spring/summer, complete with modern amenities. Like a 200 amp breaker box, and two garage 50 amp outlets are planned. So, without a car presently, and not expected to get one until next March at the earliest, I should not have that long to hold out, but will still need a solution when I get it to last a little while (6 months to one year is a rough guess).
So within the confines of my 100amp box I am trying to minimally charge a Model 3 without making drastic changes to a temporary dwelling. As I have said in other forum posts, I normally drive 104 miles a day, so the car has a bit to recharge every night (roughly 1/3 capacity).

If I call out an electrician what exactly should I be asking for trying to stay within the 100amp system? Or is that even realistic? Trying to keep costs low.

Is it likely that 30amp wall air conditioner breaker that is available, is actually available without overdoing my electrical system? And if so, is that 30amp outlet that would result from that breaker a worthwhile Model 3 charger as a gap filler until a more robust system in the new home is available?

If none of these are viable, what is a low-cost viable solution?

Other info: closest supercharge is 15 minutes away. That is also the closest dedicated EV charger.

 

[tpatana]

In your case while waiting I'd just use normal 110V outlet every night to get as much as you can, although the 1/3 capacity each day is more than that so occasionally make stop at super charger to top off.

 

[tracksyde]

Your current AC unit doesnt have a dedicated breaker?

If you're going to have an electrician come out, I think you'd want them to perform a load analysis to see how many amps you can pull from your main panel without tripping your main breaker. For example, if your appliances are generally off at night and your AC isnt running, you may have more than 30A available for car charging.

But even if you're limited to a 30A breaker for car charging, at a 24A draw you'll probably get about 20 miles per hour for charging. 5-6 hours at night would top you off for the next morning.

 

[MarioOrtegon]

With 30 amps you can charge your car for your daily commute and then some.
So In your case I would tell the guy to install an 14-30/10-30 outlet on the garage and tell him it's for a lathe or a welding machine so he won't charge you more for getting an EV.
after that you can use one of the Tesla adapters depending on the outlet that you requested to charge your car
Model 3 NEMA Adapters

 

[vgrinshpun]

Do you know if existing 30Amp outlet for the old in the wall unit is 240V? If it is, I would just use this circuit to charge at about 20 miles per hour, which for approximately 8 hours of nightly charging would yield about 160 miles of range - enough to cover your 104 miles daily commute under any circumstances.

In terms of the total panel capacity, it should work. The total capacity of the 100A, 240V panel would be around 19kW (please verify with your electrician). Since you will be charging at night, the **conservative** worst case loading would be about 12 kW which includes (some of these loads would be intermittent, but for simplicity's sake and to be conservative, I am assuming continuous load):

• AC Unit - say 4kW
• M3 Charging - say 6kW
• Other night time loads - say 2kW

So as a rough estimate 19kW capacity of the panel should be plenty to cover your loads.

As a disclaimer, your electrician is most familiar with the actual circumstances, so you should discuss everything with him, but above rough estimate can be used to frame conversation/verification with the electrician.

 

[AlanSqB]

A picture of the panel, especially that 30A breaker, would be helpful. Is your panel near your parking? If so, you might get away with a fairly inexpensive solution.

 

[Xenoilphobe]

Option 2 get a gas dryer or gas stove and use the old plug keeping your load the same.

 

[jelloslug]

I would certainly check on the availability of the 30 breaker. Your other option would be to get a dedicated 20 amp 120v circuit put in and use that. It would charge slightly faster than the normal 15 amp version (5 MPH vs 3 to 4 MPH) but put less strain on your current electrical system. Currently, Tesla offers the NEMA 5-20 adapter for the mobile connectors included with the S & X. They should offer it for the 3 also.

 

[silentsnow31802]

I charge at home from a 30amp 240v outlet (24amp max setting) without any issues. Its actually not too bad. I just unplug my drier in the garage and plug the car in when needed. I am in the same situation as you with the older house.

 

[David29]

I am puzzled by your description. How is that outside A/C powered? When you say it is an outside A/C, what exactly is outside? is it an entire A/C plugged into ...? what? Or is it the condenser for a central A/C? That unit has to be powered from somewhere and it could be a big factor in your situation. I am wondering if it is possibly operated from a separate panel...In any case, i cannot imagine you have an outside A/C without a dedicated breaker.

 

[brkaus]

The outside AC has to be powered somewhere.

Ask your electrician what is the largest 240v outlet that the house can support from this list of adaptors.

Model 3 NEMA Adapters

If you can even get 240/20a you will be fine with the amount of driving you plan on doing.

(Oops. Pretty much a repeat of one of the above posts)

 

[galbrecht7]

I am currently gathering quotes on getting a 240V line run to my detached garage. Just had my 4th electrician come today & give his thoughts. I am finding myself in a somewhat similar situation as the OP. My house is very old, but before I took ownership (10 months ago) it was completely renovated (about 2 years ago). Unfortunately the electrical service was not upgraded with the rest of the house. Meter & breaker box all updated, but still has 100 amp service.

All the electricians that have come to my house have warned that a 50amp breaker would be very close to exceeding my load. I've gotten a few suggestions.

One guy wanted to tap off the meter with a sub panel. One guy wanted to upgrade my service to 200amps. And 2 electricians have suggested going with a 30amp breaker, 240V line, and NEMA 14-30 outlet.

I'm definitely leaning towards the 30amp breaker. I think the sub panel guy was trying to bypass some code and I wasn't comfortable with that. I'm not currently in the financial situation to upgrade my service to 200amp. I was quoted $2400 just for that work & an additional $1900 for the 240V line to the garage. Prices for the work for the 30amp breaker and 240 line are much more in my current ballpark. I asked the electrician today if he could run wires for a 50amp in the conduit, but only do a 30amp breaker & 14-30 outlet, he said no problem. That way if one day I decide to go with 50amp, I only need to replace the breaker & outlet, no need to run new wire.

Granted my daily commute is not as long as the OP, I really think you'd be fine on a 30amp. I didn't know many specs on charging on 30amps, seems most info is on 50. It's too bad there aren't any specs specifically for Model 3 charging on a 30amp. But I really think it'll be adequate. I'm thinking around 20 miles of charge an hour. That's definitely the direction I'm leaning so would suggest the same for the OP. Especially if you're looking for low cost & temporary solution until your new house is built.

 

[Xminus6]

Honestly I think the charge rate is pretty linearly related to Amperage. You’re 30a breaker should net your 24a charging. So somewhere in the low 20s per hour of range. It’s also dependent on the car. My X charges at same kWh rate as my S did but the X is less efficient, so the mileage/hour is lower even though the electrical supply is the same.

For first-time EV buyers, especially Tesla buyers with their longer range, people get really worked up about the amperage of their outlet. The reality is that I charge 99% of the time at night while I’m asleep. The car being fully charged an hour or two earlier has no effect on me.

 

[sooner]

As an amendment, on additional looks, the external AC system does have a breaker of 40amps, it shares it with other systems though. As for the other systems, I assume garage electrical (so lights and opener) but I cannot read the writing on the sheet that came with the box. Will experiment some more at a future date when I can switch breakers off and find out what is not longer powered.

Thanks for the responses, more information to follow.

The range/microwave is on a 50amp breaker. I took some images, but apparently did not take one of the final major breaker, being the drier (assuming 40amp). Otherwise the rest of the home has 20amp breakers. It sounds like 30amp breaker would be sufficient, just need to make sure car charges when I am very unlikely to be making some fajitas and microwaving the shells.

Due to the small stature of the house, it is inherit that the breaker box is close to the where the car will be... everything in the home is within 10 yards of the breaker box.

So In your case I would tell the guy to install an 14-30/10-30 outlet on the garage and tell him it's for a lathe or a welding machine so he won't charge you more for getting an EV.

Unless I am mistaken, welder installs do not necessary need the same gauge of wire? I thought I had read that somewhere else. But I do not expect the price to increase being for an EV, I know the electrician I am going to ask to take an initial look, to get most of my data. Then I will get more estimates. I plan on installing the wiring myself, just not hooking it up to the box, hopefully cutting cost. Having wired my home with Ethernet and cable, I am quite familiar with crawling around in the attack and fishing wires through.

 

[brkaus]

This is my model S 100d at 24a. A Model 3 should have more driving efficiency so should get more mi/hr of charging.

245v/16a (would be a 20a plug) charges at 11 mi/hr. Again, a 3 should be more.

 

[HG Wells]

The AC is probably on a small box next to the meter. You might want to look at running from that box. Use conduit attached to the outside of house, Ask electrician if you can run the wire with electrician making all connections. Will cut his fee to under $200.

Ask him to spec wire and breaker etc.

 

[ummgood]

Unless I am mistaken, welder installs do not necessary need the same gauge of wire? I thought I had read that somewhere else. But I do not expect the price to increase being for an EV, I know the electrician I am going to ask to take an initial look, to get most of my data. Then I will get more estimates. I plan on installing the wiring myself, just not hooking it up to the box, hopefully cutting cost. Having wired my home with Ethernet and cable, I am quite familiar with crawling around in the attack and fishing wires through.

The amount of amps to the outlet determines how big the gauge of wire should be. If an outlet is rated to 30A they have to put a sufficient wire gauge to the outlet regardless of what will be plugged into it.

 

[Xminus6]

The amount of amps to the outlet determines how big the gauge of wire should be. If an outlet is rated to 30A they have to put a sufficient wire gauge to the outlet regardless of what will be plugged into it.

Yeah. If someone is installing a thinner wire than required for the breaker, that's just asking for trouble. Some welders are dual voltage so they can be run off regular household current or 220. Maybe that's what he was thinking?

 

[brkaus]

Yeah. If someone is installing a thinner wire than required for the breaker, that's just asking for trouble. Some welders are dual voltage so they can be run off regular household current or 220. Maybe that's what he was thinking?

There are welder that are put on 6-50 outlets with 40a breakers. They are allowed to be wired for 40a circuit. They did this in my parents garage. Stupid, but for whatever reason it is allowed.

 

[Cosmacelf]

First, for new, permanent installs, I highly recommend buying the Tesla Wall Connector instead of using your included Mobile Connector and plugging it into a 30A or 50A outlet. It allows you to keep your Mobile COnnector in your car, so you'll never forget it. And the Wall Connector is much more robust for daily charging.

For the OP, please answer a bunch of questions: How far away is your panel from the parking spot? Could you get by with 75 miles of charge recovery per day until your new house is built? If so on the last one, just install a new 120V, but 20A receptacle and use Tesla's NEMA 5-20 adapter for the mobile connector. And yes, that 30A breaker is certainly a possibility, depending on what other 240V loads you have (connect it to a NEMA 14-30 and use that adapter).