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Help with charging situation and installation advice!

Read around on the forums a bit but my situation is a little different. Currently I live in Michigan, but I’ll be moving to Illinois for my graduate studies and I just had the inspection done on the condo I purchased. Currently live in a home with my model Y and use a Nema 14 50 with my existing 100amp panel. The house is roughly 1900 square feet. During the inspection of the new (new to me) condo we identified that the panel in tie attached garage is in fact also a 100amp panel and has 1 slot left for an additional breaker. My thought process going into this is that there is already enough power from the panel being 100amps and the one slot here is my issue since getting a 50amp breaker for the panel would require 2 slots would my solution to this problem be maybe taking two of the 15 amp breakers and converting them into one tandem breaker, and that will give me room for the 50 amp breaker for the nema 14 50. I’m going to have an electrician do the work of course but I’m just trying to make sure I know enough of what needs to be done so I don’t get ripped off. I attached a picture of the panel.


Well-Known Member
Feb 17, 2013
United States
Would it be hard to do this myself? What things would you advise if I were to go about doing this myself

I would be hesitant about putting a 50A circuit in that panel. It 'should' be ok but you're gonna be close to the ampacity and the car probably won't be able to pull much more than 30A anyway due to voltage drop. My vote would be for a NEMA 6-20 outlet. 16A @ 240v is 3.8kW or ~14mi/hr.

I don't think it's hard but there are a lot of people that discourage DIY electrical work. Plenty of resources out there on how to install a NEMA 6-20. Depending on the run length material costs should be <$100 and could take as little as ~30 minutes to install.

... another option to consider is if one of those 20A circuits goes to a dedicated 110v outlet you don't mind losing... you can repurpose the N as a L and upgrade it to a NEMA 6-20.
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Randy Spencer

Supercharger Hunter
Mar 31, 2016
Alameda, CA
Would it be hard to do this myself? What things would you advise if I were to go about doing this myself
If you can turn off the sub-panel this stuff it pretty easy, BUT, there are LOTS of idiots out there, so I don't want to encourage an idiot to do their own electrics.

Once the power is off you can test it's off with a contactless power checker you can remove the breakers that are in there and see how easy (or hard) it is to move them up or down. You will need two slots free to add another 50 amp breaker, but there is space for it if you get a dual 15 amp breaker, take the old one to the store to be sure you are getting the right unit. Take out those two 15's above the dual 30 amp breaker and replace them with the dual 15. That will leave one slot above and one below the 30, take out the 30 and move it up one slot and re-insert it. You won't need to remove the wires like you did when you replaced the 15's.

Then attach the red wire and the black wire of a length of 8ga Romex to a new dual 50 amp breaker and clip it into the empty space. Now screw down the white wire to the neutral bus where all the white wires are attached, and the green or uninsulated wire to the ground screw. If you are mounting a NEMA 14-50 outlet run the Romex thru the unused knock-out at the bottom and protect it with a strain-relief. Hook the neutral and ground to their respective screws in the outlet and the hot leads to the other two and mount the outlet on the stud and attach the cover plate. If you are going into a HPWC directly just run the wire out thru the sheetrock and follow the installation instructions on the Tesla Wall Connector.

If you are running the outlet or the EVSE some distance from the sub-panel I might hire someone, depending on how much grunt work you wanna do. Lots of knocking holes in sheetrock and drilling holes thru studs, or you can run shielded conduit outside the wall (indoors or outdoors) and then you don't need Romex, just regular 6ga wire. Maybe 8 or 10 gauge wire depending on how much power you plan to supply. If you have a 50 amp breaker and only going 1 foot you can use 8, longer you will wanna use 6.

If instead, you use a dual 20 amp breaker you can use 10ga... Smaller number is thicker/more expensive wire. I wouldn't do this. The car may try to draw more that 20 amps worth of power unless you specifically tell it not to.
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