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What materials are needed for NEMA 14-50?
- Thread starter osubuckeyes88
- Start date
JPP
Active Member
....uuuh, did you ask your electrician??? Where and how are you running the cable? In wall? NM? Conduit? Is disconnect in the same space? Does your local authority require a disconnect? Is your utility feed adequate? Breaker panel OK? Room to expand?
I suggest that you maybe search these forums for info....
I suggest that you maybe search these forums for info....
I know that you should use some decent 4Awg copper wire like this:
https://www.lowes.com/pd/Southwire-...-Non-Metallic-Jacket-Wire-By-the-Foot/3334032
I know that you want some quality outdoor conduit with correct lengths or required junction boxes:
Southwire 3/4 in. x 25 ft. Alflex RWA Metallic Aluminum Flexible Conduit-55082321 - The Home Depot
I don't really know about the breaker equipment, disconnects, or required junction boxes.
https://www.lowes.com/pd/Southwire-...-Non-Metallic-Jacket-Wire-By-the-Foot/3334032
I know that you want some quality outdoor conduit with correct lengths or required junction boxes:
Southwire 3/4 in. x 25 ft. Alflex RWA Metallic Aluminum Flexible Conduit-55082321 - The Home Depot
I don't really know about the breaker equipment, disconnects, or required junction boxes.
countontom
Member
You'd better ask your electrician to go to home to have a check and give your a shopping list.
You need a 50-amp double pole breaker that matches your box. Look in your box and see what brand breakers are in there already. Then go to Lowes or HD to buy the same brand, but be sure it's a 50-amp double pole.
You also need a 14-50 exterior box. I bought an Eaton at Lowes. Someone else mentioned the wiring already. You'll also need 1" conduit with water-tight connectors to run the wiring thru.
I bought my own Eaton NEMA 14-50 box, with $10 breaker, and conduit, and 8' of 6/3 wire, for $75, all bought at Lowes. Your wiring alone will probably cost over $300. So, altogether under $400.
Swampgator
Active Member
eprosenx
Active Member
No.
If he runs 6 AWG copper wire and actually pulled a FULL 50 amps (not possible for an EVSE since they are limited to 40 amps on a 50a circuit as it is a continuous load, and the UMC Gen 2 is only 32 amps!) and if we use a horribly conservative voltage drop allowance of 2% (NEC recommends a max of 3%, but then also not more than 3% on feeders, with a combined total loss of 5%, so hence the being super conservative at 2%), then he still can still run it 108 feet!
If we back that down to 40 amps max draw we get 135 feet. If we up it to 3% allowed loss but back to 50 amps we get 162 feet.
Now these NEC recommendations are just that - recommendations - nearly everything in NEC is rules, but there are not rules for voltage drop surprisingly enough.
So while it is not optimal, I think that in some situations it is OK to have pretty hefty voltage drops for EV charging. Unlike some motors that work harder when their voltage is low, EV's just charge a little slower. The onboard rectifier can handle 100-240v at least, so not that big a deal if you have a lot of drop. The only trick is to avoid Tesla's throttling due to it thinking there is a wiring issue. It looks at the voltage before charging and then watches it after it starts charging. If it drops too much it assumes there is a wiring issue and will slow down or stop the charge.
I have seen wire upsizing pushed around here on the forums in a lot of situations where I just don't think it is necessary. Dealing with 4 AWG is kind of a pain compared to 6 AWG (which is still a pain).
If you upsize you can be prepared for a HCWC should you want one or get a free one for referrals. Also ready if you get a second Tesla and can load share, I would think this will be supported with other brands of charger later too.
3gauge THHN is $1.02 a foot at Home Depot and an 8 gauge ground $.56 a foot. It is early maybe my math is off but that is $260 then you need conduit. This will run the circuit capable of feeding a 90amp HCWC and allow you to charge even a LR M3 50% faster than the UMC.
You could do a 6-50 adapter which is 50amp 240 and save running a 4th wire if you want to put off HCWC purchase and just use a 50amp breaker for now. The adapter is cheaper than the 4th wire a 14-50 needs.
Now you should talk to the electrician to see if you have the capacity and if he is going.to gouge you on labor for big wire but know you have options besides bare minimum and that actually materials cost difference is NOT that high.
3gauge THHN is $1.02 a foot at Home Depot and an 8 gauge ground $.56 a foot. It is early maybe my math is off but that is $260 then you need conduit. This will run the circuit capable of feeding a 90amp HCWC and allow you to charge even a LR M3 50% faster than the UMC.
You could do a 6-50 adapter which is 50amp 240 and save running a 4th wire if you want to put off HCWC purchase and just use a 50amp breaker for now. The adapter is cheaper than the 4th wire a 14-50 needs.
Now you should talk to the electrician to see if you have the capacity and if he is going.to gouge you on labor for big wire but know you have options besides bare minimum and that actually materials cost difference is NOT that high.
Swampgator
Active Member
Yeah, my bad. I thought you needed to up-size per Tesla for installations over 100 ft. I just reread the Tesla installation instructions and it says up-size for runs over 150 ft.
eprosenx
Active Member
Yes! I should have been more clear also. I don’t think in this case the wire needs upsized due to voltage drop, but I am a fan of upsizing for future needs if you think you will use it later. I am a big fan of the Wall Connector and it can make use of pretty much whatever you give it.
The 6-50 is a good idea, though they don’t generally sell the prepared outdoor boxes with 6-50’s in them (usually only 14-50’s). That is solvable though.
The bigger callout is that #3 is too big to fit under the terminals of a 14-50 receptacle, so some kind of splice may be required. The same applies to the 50a breaker.
#3 in conduit will actually go all the way to 100a FWIW. No current model Tesla’s can use over 90 though (72 continuous).
Note that 6AWG will be fine in 3/4in conduit (at least without neutral and with a 10 awg ground - I would need to check the math on what if you also had a neutral but I think it would be fine). 1 inch will be more expensive to install. Oh, and if fully in conduit and if no upgrade was ever planned, then heck, 8 awg is technically allowed (though I would run the voltage drop calcs on that).
We also have not talked aboit what his electrical service can handle... All this talk about being ready for a HPWC at 100a might be for naught if he only has a 100a service or something.
I am going to get some quotes for a NEMA 14-50 outlet in my garage. I have a 100A panel with 6 open slots(3 on each side). I would like to install the outlet about 6-12 inches from the panel, surface mounted. I bought the NEMA 14-50 outlet(Hubbell HBL9450A) and Hubbell 4" box. So basically I just need the 50A breaker and wire. I was going to leave that up to the electrician. What type/gauge wire would I need?
eprosenx
Active Member
6 AWG is typically the recommendation. Technically you could do it with 8 AWG in conduit per NEC, but the Tesla docs recommend 6 AWG (probably just as a simplification of instructions). I would do 6 AWG regardless. (6 is the minimum if you use NM cable aka Romex)
https://www.tesla.com/sites/default.../NEMA_14-50_installation_guide_NA_US_2017.pdf
FWIW, I think these are the instructions for the UMC Gen 1 perhaps (the one above does not mention the specific 14-50r manufacturers btw, but the one below does).
https://www.tesla.com/sites/default/files/downloads/en_CA/CA-EN NEMA 14-50 Installation Guide.pdf
eprosenx
Active Member
Yes. Installs right next to the panel are very inexpensive typically if you have enough space in the panel and enough service capacity and your panel is not ancient / a fire hazard.
Note that you need a quite a bit more than two feet since you have to strip both ends back, but that is the general concept.
Also note that technically 2017 NEC calls for GFCI protection (usually via a special breaker that is stupid expensive) for any EV charging receptacle, though I personally find that overkill for use in a dry garage. It was a last minute emergency rule add and most electricians/inspectors don't seem to know it exists. Technically you might be able to call it an RV charging plug and then I don't think it has to be GFCI (though I have not verified there is not similar language elsewhere in the NEC that would now require it - the code section I am referring to is in article 625 which is EV specific).
You will also need strain relief fittings for where the wire leaves the breaker panel.
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