Master Thread: Definitive 14-50 NEMA Outlet Guide

[eprosenx]

I noticed that some of these 14-50R's have 75degsC Cu Al stamped on them. I can only presume this relates to the ampacity ratings of the wire. I had one electrician tell me that it was okay to use aluminum #6 for this job because at 90C Al is rated to carry 60A. I told him I didn't want my cabling to be boiling hot. Seems like 75C is plenty hot (167degs F).

Run screaming from that electrician. No residential breaker is rated to 90c and I am not aware of any receptacle rated for 90c. Most are 75c, some are only 60c!

I have installed #6 Cu and it gets pretty hot at 40A so I've turned down my charging current to 30A.
I think few people need a 40A charge rate on the Model 3.

Hrm, #6 copper should be totally fine at 40a. I use #6 at 48a in conduit and it does not get very warm. Is your receptacle what is getting hot? Or the wire itself?

 

[Feathermerchan]

Wire itself. Esp in hot attic. I haven't measured the temp. Its probably OK but I just don't need the 40A charge.

 

[Sophias_dad]

Hrm, #6 copper should be totally fine at 40a. I use #6 at 48a in conduit and it does not get very warm. Is your receptacle what is getting hot? Or the wire itself?

#6 NMB here at 40A, and the cable becomes only slightly warm. I haven't put the IR thermometer to it yet because it wasn't a concern.

 

[kkillebrew]

Question for DIYers. What torque screwdriver are you using to get the required torque for installing these outlets?

Just as tight as you can get it without stripping something...

 

[Sophias_dad]

Just as tight as you can get it without stripping something...

I use a 1/4" torque wrench and 1/4 socket to drive a screwdriver bit. A 3/8 drive would be way too high of a scale. Don't do this with the power on(doh), because the entire wrench will become electrified!

 

[Feathermerchan]

Tighten it till it strips and back off 1/4 turn.

First Be sure breaker is off.

I use my pliers to twist the wire strands tightly together. They are not as likely to get spread apart when the screw clamps down on them. You want all strands making contact and carrying electricity.
When you start tightening, you will feel the torque increase then level as the screw deforms the wire. Then it should feel much tighter. At that point you can stop and check to see that all strands are captured by the screw. Then bend the wire as necessary to fit the receptacle into the box. When I'm ready to mount it to the box I'll check the tightness one more time and then install the receptacle. After charging for 3 min or so, touch the box. (It had better be grounded) and see if it is hot. It may be warm but definitely not hot.

 

[eprosenx]

Just as tight as you can get it without stripping something...

Hah, yeah.

So I have a torque screwdriver, but to be honest, on breakers and receptacles I just do them really tight. With large gauge copper wire and clamp style terminals it is pretty hard to over-torque (just don't break it). With aluminum wire and with the cheap screw terminals on breakers like BR series it is easier to over-torque it and damage the wire.

I absolutely use the torque screwdriver on the Gen 2 wall connectors (have not looked at a Gen 3 yet) since they have terminals into a PCB that I don't want to damage, but I really want the torque to be sufficient not to melt things.

 

[Bill25cycle]

You could be right, I cannot find enough info on this one in their specs

Yeah, The CU/AL receptacles are usually Cadmium plated Aluminum.....

I dislike Leviton..... Other things I've had happen is that the screws applying the pressure on the wires strip much too easily, and you can't get sufficient pressure on an aluminum wire so you are forced to use copper only wiring if you are in a spot where the receptacle is not easily changed out.... But usually I throw it out and put in a Hubbell.

One thing with these hard working car charging outlets.... Always use a METAL box, and build it out with extender boxes AWAY from anything combustible, such as wood studs, stiles or rails. Might not look the prettiest, but with a 40 ampere load all night at least you can sleep if the thing starts smoking.

You might say "THE NEC DOESN'T REQUIRE THIS so I'm not doing this".... That is true.

It is also true that in the 1960's and 1970's many homes that had a "FULL HOUSE POWER - ADEQUATE WIRING CERTIFIED !!" on the mail box that were almost 100% aluminum wiring other than the door bell, system ground, and telephone wiring - that were 'flash' wired in 1 to 2 days, where the team of electricians couldn't be bothered to shine and grease all the aluminum connections, nor use the more expensive "AL devices" burned down to the ground, and the NEC didn't even 'bother' to say that Aluminum wiring must be correctly installed until the 1980's. Of course "KAISER ALUMINUM" being on the National Fire Protection Association's 'advisory board' was just a coincidence. The aluminum companies decided to 'pull' the aluminum romex off the market, including the EXCELLENT copper-clad aluminum, which was totally safe and a great product.

When I was a kid, I asked about the cheap devices being used on a home under construction.... The guy doing the wiring said 'This ain't my house!".

The "FULL HOUSEPOWER" new homes at the time, with the BIG 100 ampere electric services, were the only homes that BURNED DOWN, - meanwhile - the old homes with the 'old-fashioned' 60 ampere services worked just fine.

I had one friend whose dad was an electrical engineer, and he had his home built with a BIG 150 ampere service, since as an engineer he wanted the best of everything.... Then one day we tried a Bell and Howell 16 mm projector with a 1000 watt projection lamp plugged into the 20 ampere #10 AWG AL dining room outlet.... After a 20 minute movie the entire WALL was HOT!

 

[BrownOuttaSpec]

This
G4438388
and this
Hubbell Wiring Device-Kellems Single Receptacle Plate, 2 Gang, Silver SS701 | Zoro.com
Less than $50

Perfect links!
I've been meaning to redo mine and this was just what I needed.

 

[Feathermerchan]

Bill25cycle - Meanwhile electric utilities everywhere use Al wire throughout. From the power plant to your meter, chances are it's all Al. It's lighter and cheaper. Less tempting to steal than copper and works outside for 30+ years. The difference is that utilities take the time to properly make connections.
FWIW I can charge at 40A but choose to limit it to 30 just because I don't need more than that.

 

[eprosenx]

Bill25cycle - Meanwhile electric utilities everywhere use Al wire throughout. From the power plant to your meter, chances are it's all Al. It's lighter and cheaper. Less tempting to steal than copper and works outside for 30+ years. The difference is that utilities take the time to properly make connections.
FWIW I can charge at 40A but choose to limit it to 30 just because I don't need more than that.

Yea exactly!

Also, modern aluminum wiring used in houses is a different alloy that does not have as much thermal expansion and contraction as the stuff from the 70’s.

With proper installation and devices (receptacles) and the new alloy we probably could use aluminum for more things in houses, but folks are still weary of that.

In my house the oven and AC are aluminum. Works fine.

 

[AviP]

From a ampacity perspective, AWG being the same, CU always beats AL. If you want the same ampacity, increase the AL gauge to the next larger gauge and you will be fine.

For example, at 90C, 8 AWG CU is equivalent to 6 AWG AL as both are rated at 55 Amps.

 

[BrownOuttaSpec]

I just wanted to give an update/comparison. I had bought the External Box from post number 2 and it worked well for the last year with no issues but having the peace of mind of a higher quality plug has always been lingering in my head. I bought the Bryant plug and plate from Zoro for about $50 shipped and just finished putting it in. Huge difference in material/quality and I feel much less worrisome about heat buildup or the potential fire as I ran it for about 10 minutes at the full 40 amps and the plug/outlet connection wasn't even warm. I really liked the following:

• Having the 3/8" Hex allen key to tighten the screws into the wires instead of a flat head. Much easier to apply more torque to tighten
• Type of screw/interface when the above mentioned screw. Instead of driving a screw into the wire the Bryant brings an angled thick piece of metal to the wire to compress it closer together (Shown with the red arrows in the picture)
• Copper instead of aluminum inside of receptacle to connect to Tesla plug is

Check out my pics for the comparison between the 2. The smaller Cooper plug is the old one on the left and the bigger Bryant plug is the one I upgraded to on the right.

 

[Feathermerchan]

I actually turned mine down to 30A because I just don't need it to charge faster.

 

[jjrandorin]

(moderator note: converting to sticky thread)

 

[jeremymc7]

Regarding 30A NEMA 10-30


What would be the difference between the two Bryant outlets.

9303
RR330F

 

[Rocky_H]

Regarding 30A NEMA 10-30


What would be the difference between the two Bryant outlets.

9303
RR330F

Ah, good question. I found the listings for them, and it says in the descriptions:
9303 | Bryant
"Straight Blade Devices, Receptacles, Flush Mount, Single, Commercial/Industrial Grade, Reinforced Thermoplastic Polyester, 30A 125/250V, 3-Pole 3-Wire Non-Grounding, 10-30R, Black, Single Pack."

RR330F | Bryant
"TradeSelect, Straight Blade Devices, Residential Grade, Receptacles, Single, 30A 125/250V, 3-Pole 3-Wire Non- Grounding, 10-30R, Flush Mount, Black"

Looks like the 9303 is commercial grade, and the RR330F is residential grade. That usually has to do with two parts of it: how effective the screw terminals are where the wires attach, and how robust and tight are the spring tension parts that provide the "squeeze" in the slots where the prongs plug in. That would determine how many cycles of plugging and unplugging it can do before it loses some of that squeezing force and starts to get loose and have bad connections to the thing getting plugged in.

 

[Partsguy100]

I installed the Hubbel 9450 in preparation for my delivery and have it connected to a 40Amp breaker. I planned on setting my Grizzl-E charger to 32A as I read you can only use 80% of the capacity of the breaker for EV charging. The inspector when he came to my house actually wrote 32A MAX charging on my outlet.

As others have mentioned, I'll be charging overnight and probably could reduce the 32A output to the next lower setting, as I won't need the car until the morning. I only have 100A service in my house.

Located in Canada

 

[JCtx]

I just have the 115v charging cable that came with the car. I leave it plugged in to the wall.

I'm having the same dilemma. Tesla guy said it wasn't good to leave car connected every day at all... which is exactly what I was thinking of doing, since my wife drives from 0 to 20 miles a day on average. He said to always let the battery get discharged to about 30% (not lower than 20%), before charging it back to 90%. And that'd take like 2 days at 115V.

I'm open to suggestions for the cheapest way to solve the issue. My house is 2 years old, and with only 1 dual 115V outlet in the garage. The breaker box is on a corner of the garage (outside), so probably the easiest way would be to drill the wall and install an outlet right by the box but on the inside... but it'd be on the other side of the EV, so I'd need a long cable, like the 18' one from the wall charger, but $500 on top of installation? How long is the cable that comes with the car to hook up to a NEMA 14-50 adapter? Does the 115V cable from the car come with a regular 115V outlet, or it has to be a NEMA 14-50, like 240V dryers? All help appreciated . My wife wants a Tesla, and now that a dealer is opening next week, will probably buy her the 2021 M3 LR she wants, but need to sort this mess. By the way, the only supercharger in town is 2 miles from our house, so we'd have that option too. Not sure if it's 75kW, 150, or both (would have to investigate). Thx.

 

[Vespa]

The breaker box is on a corner of the garage (outside), so probably the easiest way would be to drill the wall and install an outlet right by the box but on the inside... but it'd be on the other side of the EV, so I'd need a long cable, like the 18' one from the wall charger

Yeah, poking thru the wall for a 14-50 outlet would be cheap and easy. You'd have a 50A breaker and the 20' cord that comes with the car can charge at 32A/7kW when you buy the $35 14-50 adapter. The included adapter is only 115V and only suitable for desperate situations.
Or for the same electrician costs, you could run a 60A breaker to a wall charger. That would get you 48A charging so instead of taking all night to charge with the included cord you could just charge overnight.

For an extra $100 or so they can run conduit thru the garage and put the charger/outlet where you want it.

Staying in the 30%-90% charge range is ideal but don't sweat it. Charge on Fridays or whatever is convenient for you.