Model 3

Electric Installation For 220v/50 AMP?

I know nothing about how electricity works regarding my electrical panel and all my breakers. I am suppose to take delivery next Friday on a M3 AWD LR, however I am very frustrated with electricians. I have had probably about 6-8 electricians come and they all tell me something different. Overview I live in an older house in NYC (Con Edison is my electric company), my electric panel is pretty much maxed out at 100 amps. Now this is where it gets confusing, I have had electricians come in and said they can add a sub/side panel with a 60 amp breaker. A couple said they would have to move my entire panel b/c its not up to code. I have had an electrician that was willing to move the panel, and add a sub panel only to cancel on me last minute b/c he wasn't confident and put his reputation on the line if something goes wrong since he was going to do it without permits, but now he wants to do it with permits and get the electrical company involved which I'm sure would at least double the price if not more, he mentioned having to possibly break the ground to get to the conduit to change the panel to 200 amps. Currently I have central air, and a stove that runs on 220. We don't want to have the breakers trip if we are trying to charge the car if we can't upgrade to 200 amps. Suggestions on what we can do? especially that won't break the bank since we pretty much went about $7000 over our budget for the car.


  • By the way charging on 110v is not an option.
  • Just a suggestion. Temp option maybe buy the right adaptor and run it off the stove outlet just to get charging while you sort the rest out.

    Also I understand 110v is not an option but thinking how fast do you need to charge?
    Some thoughts maybe a 15 or 20 amp 220 outlet this is double+ faster than the 110v but should not overload your current panel.

    Example for you to think about.

    120v 15a gives you 3 mph
    120v 20a gives you 4 mph
    240v 15a gives you 11 mph
    240v 20a gives you 15 mph
    240v 30a gives you 22 mph
    240v 50a gives you 30 mph

    So do some math see what you need to get it charged back up in the time you have. You may find that one of the lower current options is enough and your current panel can handle it. For example the 240v 15 or 20a is not that bad actually decent and should not overload what you have.

    If you only have a 100a service installing the 50a is really not even an option on a subpanel IMO. Installing a new 200a service great if you can afford it and you are staying there for years to come. But maybe one of the smaller current rates will be enough and not break the bank. You can always go with the cheaper option for now and upgrade the panel later. Idea is to be safe and not overload. I have seen people use Y splitters on there stoves and electric dryers. I don't like this but in the end breaker will kick if you overload.

    Path of least resistance most cost effective probably is go with one of the lower current 240v options. If you have not spots left over for most panels they sell double breaker (2 breakers that take the space of 1) You could install a few of this in some 15a spots to get you a few free spots on the panel you have to a new 240v breaker for the Tesla. I think if you are not going for a full 200a upgrade this could work out for you. As all your breakers are as they should be and you are not overloading.
  • BTW you don't say but are you planning on installing the wall charger?

    Reason I ask is you speak of needing a 50a line if you are just going to use the UMC that comes with the car the most it can draw is 32a so you will never max out the 50a circuit.

    If you say go for the 240v 30a option that with the cars UMC draws only 22a.

    So unless you are going to install the wall charger you really don't need a full 50a circuit as the most you will ever draw on the included UMC is 32a.

    Also you can install the NEMA 14-50 and breaker it at 40 amp no issue again as the cars UMC cannot draw more than 32a anyways.

    So most likely you don't even need a 50a circuit at the most you need 40a. This alone relieves some of the strain on your 100a panel.
  • So I followed up with the electrician that was suppose to come today, and asked him if we can do the 220/30amp and he said he wouldn't be confident in that nothing would trip when charging.
    My stove is hard-wired, so no outlet to connect an adapter to.
    Not installing the wall charger.
  • You're limited by what your house's electrical panel is capable of. Ask him if you can do 220 volt 24 amps. Or approximately that. Ask him at what lowered setting would he become confident that nothing would trip.
  • Exactly the 30a line is only going to draw 24a.
  • All right. Lets take it from the top.
    But, first: While I mess with electrons for a living, I'm not an electrician, especially the type who hangs around with the NEC (National Electric Code), which, by and large, is what's with code in local muncipalities left and right.
    First, there's the issue with the size of your panel. It's 100A. That's old and relatively small.
    Here's why: If you look at your breaker panel, you'll notice all sorts of breakers, mostly at 15A, some at 20, and some duplex (those are the 240 VAC ones) that are for whatever-it-is-in-your-house-that-needs-240, like the furnace, air conditioning if you've got it, and an electric clothes drier, if you've got one of them.
    Now, add up all the numbers. The sum of all of them will be comfortably larger than the 100A main breaker (if there is a main breaker; some of the older panels didn't have one of them) that the panel is rated for.
    However, this is what makes electricians electricians: They run what you've got there through some kind of calculation that estimates what the maximum nominal load will be on said panel. So long as that number is less than 100A, things will be good. If it's more: At some point somebody turns on a radio and the main breaker pops, Which Is Bad. As with the Mother Nature quip, it's not good to try and run more than 100A through a 100A panel. If you're lucky and The World Works Right, the breaker will pop. If it's an off day for the breaker, the alternative is that wires get 'way too hot, really, and things catch on fire. You kinda don't want you and yours lives to depend upon the functioning (or not) of a who-knows-how-old-it-is breaker.
    It's for reasons like the above that Bonded Serious Electricians, who don't like to see customers (or ex-customers) go up in smoke, will often recommend a bigger panel when that equation doesn't work out for the bigger load desired. A customer going up in smoke causes much talk to go around, wins one visits from various code enforcement agencies, and, if one's work ever gets inspected, a really hot reception from the local electrical building inspector, followed by visits by people with uniforms, and it doesn't end well.
    Yeah, a new panel is not fun, costs money, and all that. But if you can get 200A service into your house (Con Ed might have to beef up their feeder cable into your house), put in an outlet for your Telsa, and you'd be done with all that.
    This is where you find out I'm not an electrician: I'm not sure what the deal is with a sub-panel. If it's code and lets you suck 48A (that's the most you'll ever need on an M3) and doesn't violate the NEC, then I guess you're good to go with that, and maybe cheaper. But I've got this rough idea that a sub-panel goes _through_ the main panel, in which case you're not winning anything: Still too much current through the mains rated at 100A.
    Just so we're clear on this: Wires are made of copper. The bigger the diameter of the wire, the less ohmic resistance it has. So, a 4 Gauge wire (big beast) will heat up to yea with a certain amount of current running through it; a 14 Gauge wire with a much smaller diameter, more resistance (it goes by the cross-section of the wire), will run at a higher temperature with that same current.
  • Next thing. If you're going to do stuff with sub-panels and/or replacing the breaker panel, _insist_ on getting the work permitted. In NJ, next door, one doesn't actually have to have a inspection, or even a permit, for simply adding an outlet. For replacing a breaker panel or adding a sub-panel, one does.
    Now, if you've got some fly-by-nighter coming over and giving you estimates and talking fast and is cheaper.. Say you want the permits and want to see them. If the so-and-so disappears over the horizon like smoke, wipe the sweat off your brow and thank $DIETY for the near-miss.

    I used to have a college roommate who was an aspiring civil engineer. He showed me his code book (4" thick, and big, no kidding) and told me that every page in there was associated with something that had fallen down and killed people. The NEC is like that. Don't be a victim. Don't take short cuts. Get them to give you estimates and compete on price, sure, but, bottom line, insist that they've got to go the permitting route. And be there when the inspector comes by.

    In the short term: If you've got a 120 VAC outlet in the garage or near it, you can charge the car with that. My M3 gets 4-4.5 Miles of Charge Per Hour; for overnight, that's 32 miles a day, more if you leave the car plugged in what with COVID and all that. If you can get to a 240 outlet for a drier or something, you can get the appropriate adapter for the Tesla Mobile Connector (the cable in the trunk) and get up to 20-30 MoCpH that way. An occasional trip to a SuperCharger will top you off for longer trips and still be 1/3-1/2 of what you'd pay for gas. This will keep you and the car in motion until the panel's replaced (or subpanel added?) with something with more oomph.

    Finally: The Tesla Wall Connector (TWC) will give you 48A at 240 VAC and a charge rate of 45 MoCpH. I happen to have one of them. It's nice. It also cost $500, outside of the wiring and labor costs, which ran around $1500 over here. It's convenient, sure. But a fair number of people think that the money involved isn't worth it, and put in a NEMA14-50 outlet. Despite the name, the TMC won't draw more than 32A with that adapter, but you'll still get 30-odd MoCpH, which will probably be more than enough for anything you've got in mind.
    Comments, anybody?
  • @Tronguy Being a EE myself, I couldn't have said it any better. Size the panel and wire properly for the job, hire a professional, and enjoy the good life driving these wonderful vehicles.
  • What you describe sounds like a collection of electricians doing different levels of analysis. What is probably the current setup at your house is a buried service in an underground conduit sized for 100A. Which means in order to upgrade your panel, the wire has to be upsized which is requiring a larger underground conduit size. So what is most likely the case is exactly as you described. In order to upgrade your panel you will have to dig up your yard to install a new underground service.

    The thing with the 60A sub panel setup, is your risking overloading your panel if you have other appliances running, such as electric dryer, electric stove a couple TVs and charging your car could overload the 100A panel. You could however, limit charging speed on your car screen. Another approach could be to schedule charging around night time only.
  • I think 007BondMI6 has your answer.

    Install a 240V outlet, for whatever amperage your electrician is willing to sign up for - a 240V, 20A outlet would charge at 16A, and give you about 15 miles of range for every hour you charge. Plug in at 8 PM, go to work at 7AM, that's 11 hours of charging giving about 165 miles of range. As long as you're driving less than 165 miles a day, you can keep the battery fully charged (or 80%, or 90%, but that's a different argument) every day, and have plenty of margin for those days where you drive more than normal.

    Installing a 220V, 20A outlet shouldn't cost any more than installing a bog-standard 120V outlet.
  • As stated previously, if budget is really constrained, I would also look at putting in or accessing a 220v 20A or above connection. I think you will find you will easily be covered 98%+ of the time.

    I would also recommend taking an inventory of your electric draw. Because there is a lot of margin in load calculations, I suspect your can rebalance things with a sub-panel such that you are code compliant and don't need to worry about burning down your house.

    While upgraded service is always desirable, I suspect you will find you are not typically anywhere near the limit of your 100A service (load wise). Also, remember you will do most of your charging at night, when your not running the dryer, stove, microwave, hair dryers, etc all at once. Do you have gas service? If so, is upgrading an electric dryer or water heater to gas an option to free up a circuit load? To be clear, I not saying to break code because you will be charging at night, but if you find a solution you will only increase your margins by charging at night. Memory serving, the code has limits based upon load calculations as well as the number of physical breakers. Load is "usually" not the issue, but number of circuits is more often a problem but can be addressed by adding a sub panel or possible upgrading the panel (but not the service).

    If you figure out how to run a line, even if you install a 20A breaker and outlet, I would still go ahead and run cable capable for at least 50A for a 14-50 outlet so you don't need to rerun later if you upgrade your service.

    Did they discuss upgrading the panel but not the service? I think this usually gives you more flexibility than adding a sub-panel, but may trigger code requiring you to touch/upgrade other things you are trying to avoid. If you can upgrade the panel and the loads are intelligently balanced I think you will find you are actually still well under your 100A limit and won't have breakers tripping. You can always limit the charging rate some (externally or in the vehicle) and can program when to charge which gives you a lot of flexibility to manage things.

    Also, figure out your average daily commute. If most of your days are 60 miles or less then low amp 220v will be fine and high amp 220v means you will have less than a 2 hour window of potential power conflict.

    Stay code compliant, but I think you still have options. If you have an issue with something tripping, then it is more likely because the loads are not balanced well in the breaker box and if you understand the loads, you (or your electrician) can rebalance the box to better minimize load stacking.

    I would try to target a 14-50 but would be prepared to fall back to a 30A or 20A connection. Either will be workable for vast majority of people, especially 30A. I have been using a 14-50 which operates as essentially a 40A connection since the car only pulls 32A for over 2 years now and I honestly can't think of a single time that a 30A service and maybe only 1-3 times that a 20A service would have caused any level of inconvenience for me.

    Last point, while I think I could easily get by with a 20A 220v if I had to, I assume you have a garage. If you are charging outside in winter, I would want 30A unless this is a short-term solution.

    Good luck and keep us posted how this unfolds.
  • Install a NEMA 14-50 with a 50 amp breaker. Get a version 3 wall charger and plug it into the 14-50. Set the charge schedule so the car will charge In the middle of the night when your not using the stove. If you overload your panel lower the amperage in the wall charger via the web app. It’s just a menu choice, no electrician required to lower the amps.

    If you find your not happy because you have to set the wall charger too low you can always upgrade your panel later. All the electrical work to install the wall charger is required anyway so you lose nothing in trying the 14-50 with the Version 3 wall charger first.
  • All the electricians and those quoting NEC are all correct. Sure, if you do the math add things up looks really bad. But there is a simple way to find the truth for levi1994 home it’s at the end and I wonder why no electrician has suggested it or done it yet.

    OK we have reality, what happens in real life. I don’t know how big levi1994 house is, but I know my house. I also know I never ever use anywhere close to the system’s capacity at one time.

    6000sf, 4 HVAC units, electric dual oven, Tesla wall charger, and NEMA 14-50. The house has 2 150 amp service panels feeding off of a 300 amp meter panel (yes 300amp service). Plenty if of potential but how much am I really using??? I have each leg monitored counts every electron passing by and stores it for graphing and history.

    AC 1 4500 watts
    AC 2 2800 watts
    AC 3 1700 watts
    AC 4 1700 watts
    Tesla wall 12000 watts
    Tesla 14-50 with gen1 UMC 9600 watts
    Total 32300 watts if everything is at full power all at the same time, I am pulling oh round that to 135 amps. Even throw in some other items and call it 150 amps so half of the systems max.

    Looking at over 5 years of data from my home I can see that never ever did I ever draw more than 80amps as any single moment in time. So, based on this real-life data I could actually have safely run my home from a 100amp service!!! Yes, I am sure some will be in disbelief, but I have over 5 years of real time data to back it up.

    So, let’s dial that back some to fit with levi1994 panel of 100 amps.

    Let’s take the biggest AC I have 4500 watts, electric range 5000 watts, Tesla 5300 watts (for the 240v 30amp). Total 14800 watts for rounding to 62 amps. Remember it’s not uncommon for a 100amp panel to have 200amp in breakers total as not everything is used at the same time and you do have a main breaker if there were ever an issue.

    So even if levi1994 charges his car, cooks a roast, blast his AC, watches TV, has some lights on, and a few other things he is still within the limits of his 100amp panel. As we can see from my historical data running everything at the same time is actually not reality.

    Remember I have never in the past 5+ years used more than 80amps as any single moment.

    BUT levi1994 here is the real deal for your home to avoid everyone’s opinions as opinions vary so much.

    This is an easy test for any electricians and easy math. Even I have a clamp on amp meter I am sure they do too. Have them take off the panel cover turn on everything in your home that you would ever use at the same time and he can just take a live amp reading in a second. Then you have your real max draw of your exact home. Now simple math for your electrician to figure out how big of a line he can safely put for your Tesla. Now that I think of it, I don’t understand why any of those electricians did not do this so simple test that takes a few min to do. Do this simple test, find the truth for your home, then you will know what is safe, best, and the most cost-effective way to get your Tesla plug installed.
  • If anyone needs a referral code please use mine:
  • @007bondMI6

    Your system is more than likely (or should be) designed to handle everything being able to run at the same time. You can do things like schedule charging at a certain time or reduce charging speed to avoid needing to upgrade capacity.
  • andy_connor_e my systems is over designed as the previous owner planned on finishing the basement adding another 2000sf to the home.

    But the fact that I am monitoring the homes current draw 24/7 and logging it then searching the history proves that most of us never run everything at the same time.

    Based on my history I have never drawn more than 80 amps so I surely could run my home very safely on a 100 amp service. Yes did you see my total potential current draw 150 amps just never ever happens.

    Nothing against electricians I was an apprentice for 2 years but changed my path. They all need to make money and put food on the table. Fact is very likely levi1994 can add a 240v line to charge his Tesla to his existing panel for a reasonable cost. If an electrician was interested in doing right by levi1994 they would measure his current max draw with everything on and sell him an upgrade that matches his need. For some of his electricians to say he needs 200amp service without even doing some readings and math is just someone looking to make some cash (or has no clue). Again remember simple tool that measures current then simple math no magic no guessing accurate recommendation to levi1994. All an electrician needs to do is his job figure out what the customer needs.

    And andy_connor_e you are correct when is AC used mostly heat of the day, then electric range dinner time, just charge the car overnight when all are sleeping easy and no tripped breakers. I think I have proven that a 100amp service is more than levi1994 probably needs and can easily handle a reasonable Tesla charging outlet at 240v.

    Let's say for example levi1994 wants to max out his UMC at 32amps and his AC is a 5 ton unit the max size for residential another 20 amps that's only 52 amps of his 100amp service how is he going to trip anything, answer he is not. Again we are using the figures for the largest residential compressor and the max the UMC can draw. As we see simple math, simple current readings easy ways to figure out what levi1994 actually needs.

    bassbone1_98264787 not cool to hijack a thread for personal gain, just saying. Also anyone with there own account can use their own code to buy another car and gain double the rewards so no need to use others codes.
  • @andy_conner_e: My understanding is that if, in a typical house, one plugs in full loads on every single darn circuit (lots of lamps), turns on the AC, turns on the furnace, turns on the water heater, the stove, the microwave, the fridge, and all, one will pop the main breaker.
    The same math that lets the telephone company connect 100,000 subscribers on a telephony switch that can only handle 15,000 at one time is used by electricians to size breaker panels. (For telephony, for those of us who remember, it was the distinct lack of dial tone during major emergencies that was the tell.)
  • @007bondMI6

    ya, what probably happened is the electrician looked at OPs panel, added up all the breakers and said you need a larger panel. OP could easily do a sub panel and limit charging speed or do so only at night.
  • Don't be pennywise and pound foolish. The right solution is to but in a new 200A panel and then run a 60A 240V line for the Wall Charger. It's going to cost you more money but it's money you should be spending. Your old panel is out of date and possibly dangerous depending when it was put in. When I got my first EVSE I upgraded my service from 100A to 200A and had a nice new panel put in. My electrician, who I've been using for 30 years (father and son) said if my old panel was in his house he wouldn't be able to sleep at night. To be fair he told me to replace the panel in the 90s and I didn't do it then. When I got my first EVSE that was the push I needed to do it. I paid $2800 to have my new panel installed. My power comes from a pole so it might be cheaper for me then it will be for you.
  • bjrosen why is everyone just doing a random statement that 200 amps is needed did you read my post? If you have unlimited cash sure any electrician will take your cash so will a plumber or a charpender or anyone for that matter.

    What is wrong with an honest electrician doing a simple 1 min current reading and actually doing some math to see what levi1994 actual needs?

    Really the truth is don't be pound foolish when you could have been pennywise.

    Let us all remember there is a main breaker so there is NO Safety concern here At All.

    Also bjrosen why does levi1994 need a 60amp circuit as you have stated??? If he is using the included UMC it draws a MAX of 32amps so no need for 200amps or 60amp circuit you are pulling numbers out of the air.

    Again simple amp meter and simple test will tell all no need for anyone to guess. But sure if you have unlimited funds why bother to do a simple test why bother to do math just get a 200 no 300 or maybe 400 amp panel just to be safe after all it's only money right? This is why people just throw numbers out there and say get a 200 amp panel no one wants to do the simple things, some of us call it work and math.
  • Tronguy just for giggles I went to my 2 main panels 150 amps each total 300 amp service. I totaled all the breakers again just for the giggles came to 1105 amps. So if every circuit in my home were to draw its max I would be at 1105 amps holy crap that's insane. But as I have stated I have a monitor on my service measures every watt and I have never in the history of owning this home drawn more than 80 amps at a single given moment.

    Again goes to prove that people giving random advice that a 200 amp panel is mandatory is ridiculous and plain outrageous.
  • [email protected] Each panel has a main breaker, it doesn't matter if all of the sub breakers add up to much more, the purpose of the individual breakers is to protect that line not the whole house, that's the job of the main breaker. Nobody runs a full load on every line, most are barely utilized, so the total load is less than the main breaker's limit.
  • How long are you going to live at the house ? Any possibility of installing more ac or a hot tub in the future? Maybe a kitchen makeover with a double oven? Maybe a pool? Maybe with a salt generator? Do you have a panel that currently has obsolete or known problem brand breakers. No you don’t want to throw cash at anyone but upgrading your service is not the worst use of cash and if you are going to do anything it should be to code so a permit should not be a concern. Funny the person saying don’t overbuy has two 150 amp panels.
  • @007bondMI6 - I agree and already stated myself that the load is likely not the issue. Being an EE geek, I also have energy monitoring on my 400 amp service for over 8 years now and of course my average is nowhere near that limit though I can get much higher than many here, however...

    I just want to point out that one shouldn't just load their panel up because they know it is ok because they will only charge at night (for example) or have their real world usage. The code doesn't work like that. As you stated, I believe this can be solved but any solution needs to be code compliant regardless of whether we think it is overkill.

    I got the impression that his panel was maxed which I assumed to mean both load and also number of breakers. To @hal2001, adding another 220v circuit to the existing panel may not be physically possible without exceeding the allowed circuit count (and maybe load calculation for the panel) without violating code. It feels like adding a sub-panel or possibly upgrading the existing panel could work without upgrading the service but I assume there are likely code requirements his electricians are aware of that hasn't been shared with us yet. For example, he may not be allowed to add a sub-panel without opening up and addressing other things going on in his panel.

    I think the answer is simple. Ask the electricians to provide quotes with permits pulled. My guess is the OP's options will quickly shrink down to just one or two options.

    In looking back at the thread again, I think the OP hinted at the solution in his third post when asking about just adding a 30A 220v with the reputable electrician. To me this implies that electrician had a path to adding a 30A circuit that is code compliant but is simply concerned breakers will be tripping. If this is the case, then I would review the loads but almost certainly go down this path and side with others here that the charging can be managed to avoid tripping breakers.

    @OP, Whatever you do, make sure it is code compliant and has permits. You will sleep better and the next owner of your house will appreciate it. Beyond that, I'm confident your loads can be managed without tripping and you shouldn't need to go to 200A, but a quick inventory of panel will reconfirm that. If this is an option I would still price the upgrade to 200A just so you can make an informed decision.
Sign In or Register to comment.