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NEMA 14-50 install guidance for Older home

Bobo Tinker

Hi I'm Bobo
Jun 26, 2021
108
136
Houston, Texas
Hi Everyone! I’ve recently moved into an older home built about 25-30 years ago and have recently purchased a Tesla model 3 performance which I’m still awaiting delivery for.

I am worried about the feasibility of a Nema 14-50 outlet given my older home and 150 AMP circuit box. The good news is that my Stove / water heater is operated by primarily gas and not electricity. However, I do have two ac units, washer, dryer, microwave, stove, and dishwasher operating from electricity. I’ve attached photos of the circuit breaker.

did anyone else have a similar scenario find a solution that didn’t require upgrading the entire circuit to 200 or 250 amps? I could get away with a nema 14-30 outlet worst case given my driving needs.
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jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
10,352
11,695
Riverside Co. CA
I believe you are making the mistake many people make, when starting to look at home charging. You are asking the wrong question, in my opinion. The question isnt "how do I get a 14-50 outlet installed in this home?"

The question should be (to an electrician) "How much capacity do I have in my current panel for a 240v Circuit for EV charging"?


If you ask an electrician for a "14-50" they will in general, quote you what is necessary to make that happen, including panel upgrades, etc, if needed. Unless you use your car for an Uber / lyft vehicle, no one "needs" the fastest charging their vehicle can do, which in this case is 48amps or 44-45 miles an hour charge rate, at home.

I have it, but its not worth upgrading a panel for or something.

Let an electrician tell you how much capacity you have, without upgrading the panel. Could be 20 amps, 30 amps, 40 amps. Whatever it is, its likely fast enough for overnight full charging of your EV.

TL ; DR, ask an electrician for a load calculation to find out what capacity you have in your current panel for EV charging, vs "I want a 14-50".
 

Frank99

April 2018 Model 3 LR RWD, EAP, FSD
Apr 7, 2016
317
413
Arizona
You’ll need to have an electrician do a load calculation to see if the panel can support another load. I’m not an electrician, so I won’t opine on that.

That panel is pretty full, but if the load calc shows that the panel can support it, an electrician can get duplex 240v breakers to install a new circuit.

good luck
 
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Sophias_dad

Supporting Member
Supporting Member
Jul 29, 2018
1,470
1,495
Massachusetts
That panel is STUFFED! I see the panel is only rated for 150 amps, so you'd be looking at a pretty big job to move to a new panel even if your feed wires are good for 200(pretty unlikely). Just looking at the 240 volt loads you have, its already at its max (50+40+40+30), assuming they are all drawing their full ratings(which they most definitely aren't).

The only not-duplexed breaker in that entire panel is the 50 amp breaker going to the AC's. I assume there's a subpanel splitting that AC load into two separate lines.

I gotta say, before I invested anything in upgrading that panel, I'd run a gas line to the dryer(and buy a new dryer!) and by doing so I'd save a ton of dough on electricity, free up a 40 amp breaker, and so on. A gas dryer can be run off the same plug as its nearby washer. Could do the same with the oven.

But yeah, you need a real load calculation to be sure. How many miles do you actually drive every day? 8 hours on a 6-20 will get you 120 miles, while on a 14-30 you'll get 176. Can you charge at work?
 
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Bobo Tinker

Hi I'm Bobo
Jun 26, 2021
108
136
Houston, Texas
That panel is STUFFED! I see the panel is only rated for 150 amps, so you'd be looking at a pretty big job to move to a new panel even if your feed wires are good for 200(pretty unlikely). Just looking at the 240 volt loads you have, its already at its max (50+40+40+30), assuming they are all drawing their full ratings(which they most definitely aren't).

The only not-duplexed breaker in that entire panel is the 50 amp breaker going to the AC's. I assume there's a subpanel splitting that AC load into two separate lines.

I gotta say, before I invested anything in upgrading that panel, I'd run a gas line to the dryer(and buy a new dryer!) and by doing so I'd save a ton of dough on electricity, free up a 40 amp breaker, and so on. A gas dryer can be run off the same plug as its nearby washer. Could do the same with the oven.

But yeah, you need a real load calculation to be sure. How many miles do you actually drive every day? 8 hours on a 6-20 will get you 120 miles, while on a 14-30 you'll get 176. Can you charge at work?
Thank you for this information! Yup, upgrading panels is definitely something I would like to avoid because I don't even know how my existing wiring is given how old the home is. I work from home so charging at work is not an option. Our washer and dryer is built into one unit and we just bought it brand new so not sure about splitting it or going gas for it. I drive about 30-40 miles daily and maybe once a week 100-120 miles in a day. I definitely don't need a Nema 14-50 and would bemore than fine with a 6-20 or a 14-30. It seems like the best way to find out is to do a load calculation and then see what is the maximuim AMP plug I can fit in.
 
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Braumin

Member
Mar 5, 2021
54
53
Canada
I believe you are making the mistake many people make, when starting to look at home charging. You are asking the wrong question, in my opinion. The question isnt "how do I get a 14-50 outlet installed in this home?"

The question should be (to an electrician) "How much capacity do I have in my current panel for a 240v Circuit for EV charging"?


If you ask an electrician for a "14-50" they will in general, quote you what is necessary to make that happen, including panel upgrades, etc, if needed. Unless you use your car for an Uber / lyft vehicle, no one "needs" the fastest charging their vehicle can do, which in this case is 48amps or 44-45 miles an hour charge rate, at home.

I have it, but its not worth upgrading a panel for or something.

Let an electrician tell you how much capacity you have, without upgrading the panel. Could be 20 amps, 30 amps, 40 amps. Whatever it is, its likely fast enough for overnight full charging of your EV.

TL ; DR, ask an electrician for a load calculation to find out what capacity you have in your current panel for EV charging, vs "I want a 14-50".
100% agree. You need to get a load calculation done to see what kind of capacity in terms of watts is left in your panel. I had a 100 Amp panel and I was able to do a 14-30 plug which is plenty of charging for me. Everyone wants a 14-50 but unless you use like all of your charge every day and need it full in the morning you likely don't need that much. Yes, it is nice, but if it means upgrading your service it's likely not worth it.

Your panel is pretty full though. Is there room for a 2 pole breaker still?
 
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Bobo Tinker

Hi I'm Bobo
Jun 26, 2021
108
136
Houston, Texas
So... what you are saying is you really don't NEED even a 6-20 ! Even a 15-20 will get you 7 mi/hr, or 168 miles per day.
Yeah I think reflecting upon this even if I get a 15-20 it will be more than enough. Anything that isn't the standard wall outlet charging at 3 miles an hour. Thanks I will look through the recommended Tesla Electricians and have one do a load calulcation and see what is the maximuim I can do. The good news is that the breaker is in my garage so the wiring won't have to go far at all.
 

Sophias_dad

Supporting Member
Supporting Member
Jul 29, 2018
1,470
1,495
Massachusetts
standard wall outlet charging at 3 miles an hour
Its actually four or even five, btw.

I see your garage door circuit is 20 amps. The garage door itself can be completely ignored for charging purposes(see my post history for justification). I wouldn't hesitate to plug in a 15-20 UMC to that circuit, assuming the GDO is the only thing on it currently. Additionally, if it IS the only thing on it currently, you could potentially make it a 240 volt circuit without too much pain(and make the GDO a daisy-chain off another garage outlet)
 
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Bobo Tinker

Hi I'm Bobo
Jun 26, 2021
108
136
Houston, Texas
Its actually four or even five, btw.

I see your garage door circuit is 20 amps. The garage door itself can be completely ignored for charging purposes(see my post history for justification). I wouldn't hesitate to plug in a 15-20 UMC to that circuit, assuming the GDO is the only thing on it currently. Additionally, if it IS the only thing on it currently, you could potentially make it a 240 volt circuit without too much pain(and make the GDO a daisy-chain off another garage outlet)
That does seem like a good idea. We do have a freezer (regular outlet) and sprinkler system hooked up in our garage. Not sure which outlets it is piggy backing off of. I did notice that according to the sheet assumined that it is filled out accurately. The bottom half of 6 and all of 8 seems to be "open"
1626231522016.png
 

Sophias_dad

Supporting Member
Supporting Member
Jul 29, 2018
1,470
1,495
Massachusetts
The bottom half of 6 and all of 8 seems to be "open"
Sorry, that circuit description map has got to be wrong. The 'Stove' is gonna be the paired 30 amps in the middle of that pair, and if there wasn't >something< connected to the other two 20's on that pair, the electrician wouldn't have installed that type of breaker. Chances are good that 6 and 8 >used< to be a standard 30 amp double pole breaker and someone wanted a couple more circuits, because apparently in your house you can never have too many!
 
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mrau

Authorized Driver
Supporting Member
Nov 12, 2018
441
839
Mid-Michigan
If you set your car to charge at night (after 11pm) like many of us do, you likely won't be using the dryer or oven at that time. That should give you more peace of mind that you won't overload the panel.

Consider putting in the largest circuit (up to 50 amp) that an electrician says your panel will handle. You can always turn down the actual amp draw in the car if needed. The car will remember the setting each time until you change it.
 

dhrivnak

Active Member
Jan 8, 2011
4,494
3,761
NE Tennessee
What is you average KWh/month? If under 1500 I think you would be fine. Refrigerators and microwaves are low draw. And it looks like you do have two open breaker slots for a 240v breaker.

PS I have a 200 amp panel, all electric home including hot water and stove. We have 3 NEMA 14-50’s for up to 3 EVs. Right now we only have 2.
 
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Bobo Tinker

Hi I'm Bobo
Jun 26, 2021
108
136
Houston, Texas
What is you average KWh/month? If under 1500 I think you would be fine. Refrigerators and microwaves are low draw. And it looks like you do have two open breaker slots for a 240v breaker.

PS I have a 200 amp panel, all electric home including hot water and stove. We have 3 NEMA 14-50’s for up to 3 EVs. Right now we only have 2.
We are at about 1450 KWH/month but we just moved here less than two months ago so we don’t have enough sample size to make the assumptions. Wow that is pretty good! Glad to see you guys have so many EVs. Which location or spot are you seeing the open break slot for the 240V breaker?
 

dhrivnak

Active Member
Jan 8, 2011
4,494
3,761
NE Tennessee
We are at about 1450 KWH/month but we just moved here less than two months ago so we don’t have enough sample size to make the assumptions. Wow that is pretty good! Glad to see you guys have so many EVs. Which location or spot are you seeing the open break slot for the 240V breaker?
To me it looks like you have two tabs at the bottom one on each side.
 

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