Help installing NEMA 14-50 in garage

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hackdroot

Well-known member
Joined
Apr 15, 2017
Messages
93
Location
East Bay Area, CA
So in preparation for my new leaf, Im planning to use the Clipper Creek HCS-40P with the NEMA 14-50 plug to avoid having to install a disconnect in my garage. My main panel is outside and I plan on installing the NEMA outlet on the garage wall on the internal side of the wall.

In the attached pictures, the middle breaker on the right and it's associated wiring will be removed and replaced with a 40amp breaker and #8 wiring.

This seem like a real easy install since the wiring exits the wall right after it exits the main panel. it's only about 36 inches of conduit run horizontally from there, then the NEMA enclosure. I'm just not sure which is the 'right' way to transition the wiring from inside the finished wall to a conduit running on the outside of the finished wall to the NEMA outlet enclosure.

I would think romex from the breaker out of the main panel, into the wall, then through the drywall into a wall mounted junction box.

The second picture below is not mine, but demonstrates what I was thinking.

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44448d1327192478-no-splice-made-does-metal-j-box-need-grounded-100_7872.jpg
 
Why do you need to run any exposed conduit? Cutting and patching the drywall is probably easier that dealing with a transition in wiring types. Plus you could recess the box containing the NEMA 14-50 receptacle.

BTW, if you use a NEMA 14-50 receptacle, I would say it is proper to run the neutral wire, even though the EVSE doesn't use it. NEMA 6-50 would avoid this issue.

Cheers, Wayne
 
wwhitney said:
Why do you need to run any exposed conduit? Cutting and patching the drywall is probably easier that dealing with a transition in wiring types. Plus you could recess the box containing the NEMA 14-50 receptacle.

Is it really though? It seems changing wiring type would be far quicker and easier than: cutting the drywall, drilling through the studs, mounting the box on the studs, replacing the drywall, patching/sanding the drywall, and then painting the walls back to finished color. My garage is finished and painted so I mentally walked through both options and it seemed easier to run a flex conduit outside the wall.

EDIT: Looking at it again, my horizontal run may include a 90deg turn to mount the station on the forward facing wall of the garage as well. I didn't realize how short the cord from the charging station really was to the NEMA. This may complicate burying the wires as well.

wwhitney said:
BTW, if you use a NEMA 14-50 receptacle, I would say it is proper to run the neutral wire, even though the EVSE doesn't use it. NEMA 6-50 would avoid this issue.

Cheers, Wayne

You're correct and it appears that amazon has the same unit with the 6-50. I should just do the 50A breaker and #6 wiring instead though since it's recommended by the vendor in the product Q&A.
 
hackdroot said:
My garage is finished and painted so I mentally walked through both options and it seemed easier to run a flex conduit outside the wall.
In that case, maybe so. I guess I assumed that if you were OK with exposed conduit, your garage probably wasn't finished and painted.

But now that you say your garage is finished and painted, I suggest considering concealing the wiring so it will look better. :)

Either way will work.

hackdroot said:
You're correct and it appears that amazon has the same unit with the 6-50. I should just do the 50A breaker and #6 wiring instead though since it's recommended by the vendor in the product Q&A.
I'm surprised that Clipper Creek would suggest a 50 amp breaker for a 32 amp EVSE. A 40 amp breaker would be fine with #8 NM/2 on a 6-50 receptacle.

BTW, for a 50 amp circuit, if you run conduit the whole way, you could pull individual #8 THHN conductors, which have an ampacity of 50 amps. NM is limited in its ampacity to a lower value, so it would require #6 NM to get to 50 amps. You could e.g. run some FMC in the wall and transition over to EMT for the exposed run.

To answer your original question, if you want to run NM in the wall and transition to EMT exposed on the garage wall, yes, use a junction box, come into the back of the box with the NM (use a cable clamp), and run EMT out the side of the box. If you want to splice the NM in the junction box to individual THHN conductors, then there's a required minimum volume for the box: 15 in^3 for 8/2 NM, 21 in^3 for 8/3 NM, 25 in^3 for 6/2 NM, and 35 in^3 for 6/3 NM. [Edit: those numbers assume that any cable clamps are outside of the box. If there's a cable clamp inside the box, add 3 in^3 for #8 NM and 5 in^3 for #6 NM.]

Stripping the sheathing off the NM cable for the length of the EMT conduit run is a bit of a gray area, as the individual conductors in the NM cable typically aren't marked with their type, even when the manufacturer says they are THHN or whatever. Otherwise it would be the most convenient option.

Running the cable with its sheath through your EMT is another option, although it's not clear how to clamp the cable when it reaches the box with the receptacle (although you could omit the clamp where the cable emerges from the wall). You'd also want to upsize your EMT so the fatter cable will go through it more easily.

Cheers, Wayne
 
I am going to be wiring a NEMA 14-50 for my EVSE as well but plan to wire a 50A breaker and 6 gauge wire. I think at 40A you should be okay with 8 gauge but you probably want copper and not aluminum wire. You will need a total of four wires for the 14-50. One hot on each side, a neutral at the bottom and ground at the top. Normally you put a 14-50 receptacle in a box which you knock out a plug to feed the wire into. There will probably be a clamp as the wires enter to box to hold them in place so that they don't move from their connections on the 14-50 and you will want to ground the box as well. I am not a certified electrician but this should be pretty easy for the short run you have. I need to go 40 ft with 7 90 degree bends on the outside of my house and I am starting to think I should just hire an electrician to see if they could run it inside somehow. I think I am going to need 1 1/4 inch conduit going across the front of my house and above my front door with the 6/3 UF wire. Good luck with your project.
 
hackdroot said:
I didn't realize how short the cord from the charging station really was to the NEMA. This may complicate burying the wires as well.
Yeah, the input cord on an EVSE is limited to 12", as a big point of the EVSE is to provide ground fault protection. The cord, being upstream of the EVSE, won't be covered by the ground fault protection, so its length is limited.

Cheers, Wayne
 
4CloverLeaf said:
I think at 40A you should be okay with 8 gauge but you probably want copper and not aluminum wire.
I'm not sure if aluminum #8 wire is generally available, but if it is, for most wire types its ampacity will be 40A (75C ampacity, excludes NM cable).

4CloverLeaf said:
I need to go 40 ft with 7 90 degree bends on the outside of my house
Conduit systems are limited to 360 degrees of bend between pull points, so if you do this in conduit you'll have to provide at least one pull point midway.

4CloverLeaf said:
I think I am going to need 1 1/4 inch conduit going across the front of my house and above my front door with the 6/3 UF wire.
If most of the run is going to be exposed or buried 6/3 UF, then you could use a short run of conduit to protect the UF cable where exposed to damage. If you have a complete conduit system, then you'd be better off running individual THWN conductors.

Cheers, Wayne
 
wwhitney said:
But now that you say your garage is finished and painted, I suggest considering concealing the wiring so it will look better. :)

Either way will work.

To be honest, my garage has so much stuff, once the conduit is painted, it will barely be noticable. ;)


wwhitney said:
I'm surprised that Clipper Creek would suggest a 50 amp breaker for a 32 amp EVSE. A 40 amp breaker would be fine with #8 NM/2 on a 6-50 receptacle.

Based on the statement below, I'm was guessing that there's some NEC requirements for the 6-50.


"Hello, For the plug in HCS-40P we recommend a 50A circuit going to the appropriate outlet (NEMA 6-50), this matches the installation requirement of the outlet you would be plugging the station into. For our hardwired HCS-40 we would recommend the station be installed onto a dedicated 40A circuit. Here is a link to the installation/ operations manual for the HCS-40 product line - http://www.clippercreek.com/store/wp-content/uploads/2015/07/HCS-User-Manual.pdf see less
By ClipperCreek SELLER on July 8, 2015"

Based on the following link though, the NEC code apparently dictates that you can use a 40 amp circuit on that 50A NEMA: https://diy.stackexchange.com/questions/25421/why-is-it-ok-to-use-a-50-a-receptacle-on-a-40-a-circuit
 
hackdroot said:
Based on the statement below, I'm was guessing that there's some NEC requirements for the 6-50.
There's no basis in the NEC for Clipper Creek's suggestion of using a 40 amp circuit for their hardwired HCS-40, but a 50 amp circuit for a receptacle for their HCS-40p. You could use a 40 amp circuit for the HCS-40p, that would fine, it's up to you. #8 Cu will be a little easier to work with than #6 Cu.

Cheers, Wayne
 
wwhitney said:
hackdroot said:
Based on the statement below, I'm was guessing that there's some NEC requirements for the 6-50.
There's no basis in the NEC for Clipper Creek's suggestion of using a 40 amp circuit for their hardwired HCS-40, but a 50 amp circuit for a receptacle for their HCS-40p. You could use a 40 amp circuit for the HCS-40p, that would fine, it's up to you. #8 Cu will be a little easier to work with than #6 Cu.

Cheers, Wayne

Then so it shall be. Thank you Wayne for your time and expertise. Happy Easter. :D
 
wwhitney said:
There's no basis in the NEC for Clipper Creek's suggestion of using a 40 amp circuit for their hardwired HCS-40, but a 50 amp circuit for a receptacle for their HCS-40p.
I think the basis is simply that someone might, in the future, look at the NEMA 14-50 receptacle, and logically conclude "Ah, a 50 amp circuit!". So breaker it accordingly. (You might even want to plug in something different yourself, someday.)
 
wmcbrine said:
I think the basis is simply that someone might, in the future, look at the NEMA 14-50 receptacle, and logically conclude "Ah, a 50 amp circuit!". So breaker it accordingly. (You might even want to plug in something different yourself, someday.)
Let me disagree that it would be logical--the NEMA receptacle ratings jump from 30 amps to 50 amps, so 50 amp receptacles cover both 40 amp and 50 amp circuits. There are plenty of electric ranges, for example, that only require a 40 amp circuit, but use a NEMA 14-50 plug.

Anyway, should a 50 amp load be plugged into a NEMA 14-50 receptacle which is on a 40 amp circuit, the worst that should happen is that the breaker would trip.

Cheers, Wayne
 
It seems to me that labor is the greatest expense. Yes you can use it on a 40A circuit but the cost of upgrading the lines to #6 instead of #8 is minimal. That way you do not need to label the outlet. The ground and neutral can remain #8. It also makes sense to run a neutral wire even though it is not needed for an EVSE. Make the wiring proper for future use. You never know what a future owner needs. A 50A outlet should be wired for 50A.
 
GlennD said:
It seems to me that labor is the greatest expense. Yes you can use it on a 40A circuit but the cost of upgrading the lines to #6 instead of #8 is minimal. That way you do not need to label the outlet. The ground and neutral can remain #8. It also makes sense to run a neutral wire even though it is not needed for an EVSE. Make the wiring proper for future use. You never know what a future owner needs. A 50A outlet should be wired for 50A.
+1 but personally I'd go with #6 for neutral and if using #6 for the hots. When I first ran my 14-50 outlet in the garage I thought I'd save a little bit of money and omit the neutral, that was a mistake! I later decided I wanted to occasionally use 120v off the 14-50 outlet, only I didn't have a neutral :x In the end it ended up costing me quite a bit more to add the neutral, vs had I just done it from the start :( While it may be rare to ever need 50a @ 120v for the cost of upgrading the neutral to #6, I'd do it :) Oh and yes I understand any draw on the second 120v leg would subtract current from the neutral, still might as well just keep everything #6, well I guess except for the ground which AFAIK can be one size smaller than the rest, or at least it is in romex wiring.....
 
GlennD said:
The ground and neutral can remain #8.
So it's not actually clear to me whether the neutral on a branch circuit is allowed to be undersized relative to the ungrounded conductors. Certainly it can be on a feeder, and certainly it often makes sense from a loading perspective. However, the NEC has specific language regarding downsizing the neutral on a feeder, and I'm not aware of any corresponding language on branch circuits.

As to the EGC (ground), a #10 copper is good up to 60 amps (Table 250.122).

GlennD said:
It also makes sense to run a neutral wire even though it is not needed for an EVSE.
I agree if installing a 14-50 receptacle, however it makes sense to me to install a 6-50 receptacle and skip the neutral.

GlennD said:
A 50A outlet should be wired for 50A.
I'm going to have to disagree, as a corollary would be that you can't use a receptacle for a 40 amp circuit, i.e. all 40 amp circuited EVSEs would need to be hardwired. This makes less sense to me than simply understanding that when you see a 50 amp receptacle, it may not be on a 50 amp circuit.

BTW, if using any 75C insulated wiring method (basically anything other than NM), then #8 Cu is good for 50 amps, in which case it would not be required to rerun the wiring should a 50 amp circuit be required in the future.

Do you happen to know if there are any internal differences between the HCS-50 and the HCS-40, other than the pilot signal? Is the HCS-50 of beefier construction? If so, that would be an argument for using a 40 amp breaker with the HCS-40, in that it will provide a greater level of safety against a failure in a car charger causing a current draw in excess of the limit advertised via the pilot signal. Not so likely, of course.

Cheers, Wayne
 
jjeff said:
+1 but personally I'd go with #6 for neutral and if using #6 for the hots. When I first ran my 14-50 outlet in the garage I thought I'd save a little bit of money and omit the neutral, that was a mistake! I later decided I wanted to occasionally use 120v off the 14-50 outlet, only I didn't have a neutral
What load do you have that is suitable for a 50A 120V circuit? Or did you add an additional 20A or 15A circuit breaker to protect your 120V loads? In which case you basically have a feeder, which should obviously have a neutral.

I guess my perspective is that the typical case for the EVSE receptacle is that the EVSE gets plugged into it and remains that way for the life of the EVSE. I see the receptacle as dedicated to the EVSE. If "what if" situations are of concern, then it would be best to run a feeder to the garage and install a subpanel there, so that whatever other power needs may arise can be easily satisfied.

Cheers, Wayne
 
Clipper Creek HCS owner manual shows either 40- or 50-ampere breaker with NEMA 6-50 or 14-50 receptacle for HCS-40P and only 50-ampere breaker for HCS-50P. This is consistent with NEC allowance of 40-ampere breaker with 50-ampere receptacle for 40-ampere circuit. I purchased the HCS-50P with 14-50 plug for my workshop/garage which has a 50A "RV" receptacle to take full advantage of the circuit. It has a heavy duty cord and 1772 plug while the HCS-40P has an output cord and plug more like other 32-ampere units.

Anyone planning to install a plug-in EVSE with a new receptacle should determine the mounting location for the EVSE first and then install the receptacle where needed to match the cord. I could not mount my HCS-50P on the wall at an appropriate height within reach of the existing receptacle so I fabricated a portable pedestal that I can move around. I then purchased a 15-foot No. 6 AWG copper "RV" extension cord to use between the receptacle and the EVSE. "Welder" extension cords are also available for 6-50 receptacles.

By the way, temperature derating in my climate leads to No. 6 copper for 50-ampere circuits that are not in conditioned space.
 
wwhitney said:
jjeff said:
+1 but personally I'd go with #6 for neutral and if using #6 for the hots. When I first ran my 14-50 outlet in the garage I thought I'd save a little bit of money and omit the neutral, that was a mistake! I later decided I wanted to occasionally use 120v off the 14-50 outlet, only I didn't have a neutral
What load do you have that is suitable for a 50A 120V circuit? Or did you add an additional 20A or 15A circuit breaker to protect your 120V loads? In which case you basically have a feeder, which should obviously have a neutral.
Cheers, Wayne
While not 50a, when I first got my Juicebox EVSE I wanted to verify the maximum amperage my Leaf could charge on 120v, in the end I found out it was the same as on 240v which was 27.5a but other than the testing I haven't used that high of charging on 120v. Another thing I use my 14-50 garage outlet for is back-feeding my main panel from my 40a 240v generator. In this case it would be possible(although probably not likely) to run up to 40a @ 120v(from several 120v devices hooked to my main panel). And yes during the power outages my main house breaker is OFF, don't want to be powering up the grid :shock:
 
jjeff said:
Another thing I use my 14-50 garage outlet for is back-feeding my main panel from my 40a 240v generator.
Don't do that. Install a manual transfer switch or breaker interlock, along with an inlet. That avoids the use of suicide cords and provides greater security against killing linesmen.

Cheers, Wayne
 
GerryAZ said:
By the way, temperature derating in my climate leads to No. 6 copper for 50-ampere circuits that are not in conditioned space.
Good point, for 90C insulated conductors, #8 Cu is only good for 50 amps up to an ambient temperature of 104 degrees F. For ambient temperatures of 105 to 140 degrees F, #6 Cu is required for 50 amps.

Cheers, Wayne
 
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