wmcbrine
Posts: 93
Joined: Sun Aug 09, 2015 3:23 am

Re: Help installing NEMA 14-50 in garage

Sun Apr 16, 2017 9:08 pm

wwhitney wrote: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.)

wwhitney
Posts: 666
Joined: Sat Jul 17, 2010 10:10 am
Delivery Date: 01 Apr 2011
Location: Berkeley, CA

Re: Help installing NEMA 14-50 in garage

Sun Apr 16, 2017 9:29 pm

wmcbrine wrote: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

GlennD
Forum Supporter
Posts: 1179
Joined: Sun Dec 18, 2011 7:14 pm
Delivery Date: 20 Jul 2013
Leaf Number: 410357
Location: Anaheim

Re: Help installing NEMA 14-50 in garage

Mon Apr 17, 2017 10:04 am

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.
2012 Cayenne Red SL traded for:
2013 Pearl White SL Premium
Traded for a Cirrus White 2014 Mercedes B (totaled)
2016 Urano Gray eGolf SEL w/ drive assist
Loved the VW but it sat too low for my old body
Back to a Cirrus White 2017 B250E

jjeff
Posts: 1457
Joined: Wed Jan 13, 2016 9:10 am
Delivery Date: 13 Jul 2014
Leaf Number: 422121
Location: MSP MN

Re: Help installing NEMA 14-50 in garage

Mon Apr 17, 2017 10:49 am

GlennD wrote: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.....
2012 SL purchased used 2/'16
2013 S w/QC purchased new
Juicebox Premium 60a L1/L2 EVSE, Ebusbar 16a L1/L2 EVSE
'12 EVSEupgrade'd 20a L1/L2 EVSE, '13 EVSEupgrade'd adjustable 6-20a L2, 6-13a L1 EVSE
Zencar 13, 20, 30a L1/L2 portable EVSE
GE Durastation 30a

wwhitney
Posts: 666
Joined: Sat Jul 17, 2010 10:10 am
Delivery Date: 01 Apr 2011
Location: Berkeley, CA

Re: Help installing NEMA 14-50 in garage

Mon Apr 17, 2017 11:10 am

GlennD wrote: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 wrote: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 wrote: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
Last edited by wwhitney on Mon Apr 17, 2017 11:20 am, edited 3 times in total.

wwhitney
Posts: 666
Joined: Sat Jul 17, 2010 10:10 am
Delivery Date: 01 Apr 2011
Location: Berkeley, CA

Re: Help installing NEMA 14-50 in garage

Mon Apr 17, 2017 11:17 am

jjeff wrote:+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

GerryAZ
Gold Member
Posts: 1454
Joined: Mon Nov 22, 2010 6:47 pm
Delivery Date: 12 Jun 2011
Location: Phoenix, AZ

Re: Help installing NEMA 14-50 in garage

Tue Apr 18, 2017 4:30 am

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.
Gerry
Silver LEAF 2011 SL rear ended (totaled) by in-attentive driver 1/4/2015 at 50,422 miles
Silver LEAF 2015 SL purchased 2/7/2015

jjeff
Posts: 1457
Joined: Wed Jan 13, 2016 9:10 am
Delivery Date: 13 Jul 2014
Leaf Number: 422121
Location: MSP MN

Re: Help installing NEMA 14-50 in garage

Tue Apr 18, 2017 6:55 am

wwhitney wrote:
jjeff wrote:+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:
2012 SL purchased used 2/'16
2013 S w/QC purchased new
Juicebox Premium 60a L1/L2 EVSE, Ebusbar 16a L1/L2 EVSE
'12 EVSEupgrade'd 20a L1/L2 EVSE, '13 EVSEupgrade'd adjustable 6-20a L2, 6-13a L1 EVSE
Zencar 13, 20, 30a L1/L2 portable EVSE
GE Durastation 30a

wwhitney
Posts: 666
Joined: Sat Jul 17, 2010 10:10 am
Delivery Date: 01 Apr 2011
Location: Berkeley, CA

Re: Help installing NEMA 14-50 in garage

Tue Apr 18, 2017 7:45 am

jjeff wrote: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

wwhitney
Posts: 666
Joined: Sat Jul 17, 2010 10:10 am
Delivery Date: 01 Apr 2011
Location: Berkeley, CA

Re: Help installing NEMA 14-50 in garage

Tue Apr 18, 2017 7:51 am

GerryAZ wrote: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

Return to “EVSE / Charging Equipment and Networks”