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Adding a ground wire to a romex w/o a ground conductor?

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mrVanagon

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Jul 21, 2015
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105
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Belleville, IL, USA
Greetings all,
First, the setup:
I'm in the early stages of wiring a 20x24 detached garage. My garage is in a town that's covered by the 2005 NEC. I don't plan to do a lot of electric-intensive work there but I do plan to eventually install a 4-post auto lift. I intend to place a 240 outlet at each interior corner of the garage. All of the lifts I'm considering call for 220 @20 amps. I plan to wire these outlets with bigger wire than needed so that I can use this circuit for an electric car charger in the future so I'm thinking I should rig for 220@30 amps for these. This will never have more than one device running at a time.

Now the question:
I have a quantity of 8-3 romex on hand. I see that I can have a 30A circuit run about 15' with 8AWG wire. My romex doesn't have a ground conductor in it. Can I run a single conductor wire to my outlet to serve as a ground conductor or does it have to be inside the same cable?
 
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manwithtools

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Aug 24, 2015
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Lebanon, TN
BTW, 8 ga romex is good for 40 amps and any distance you might reasonably run inside a 20' x 24' garage. It's not limited to 30 amps and 15'.

240 volt car charger will require a 40 amp circuit, most lifts a 20 amp circuit, compressors and welders somewhere in between.
 
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mrVanagon

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Joined
Jul 21, 2015
Messages
105
Location
Belleville, IL, USA
It's definitely labeled 8-3 on the jacket and there are only 3 conductors in the cable (Red, Black, White). There is no ground. I think this a leftover from an oven receptacle that was wired in the early '90s when a ground was not required for such devices. I'd ask the guy who bought it but he passed away since then.
 
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mrVanagon

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Jul 21, 2015
Messages
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Belleville, IL, USA
I cut a few inches of the jacket off and checked for that. There are only 3 conductors in this cable. I'll toss it back on the pile of stuff to use maybe someday and just buy enough 6-3 w/ground to do the job. Proper is often also easier.
 
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mrVanagon

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Jul 21, 2015
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Belleville, IL, USA
On further research, Tesla cars (and probably others) use NEMA 14-50 outlets with 6awg wire. Since I don't know what sort of car charger I will need in the future but the NEMA 14-50 is currently a standard outlet being used, it seems reasonable to just wire for those. I could always make an adapter cord for whatever lift I buy (and install the correct, probably 20A, breaker)
 
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Charles (in GA)

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Jan 11, 2006
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Location
50 mi south of Atlanta
If it is old Romex NM and not NM-B then you cannot use it even if it had a ground, as the code no longer recognizes straight NM rated at 60°C, it now has to be NM-B rated at 90°C as a minimum.Cars such as the LEAF have a 6.6kw charger in them, that is 27.5 amps and many Level 2 EVSE's are rated for up to 30 amp, and Article 625 of the NEC says that circuits for EVSE's has to be considered continuous and the 80%/125% rule comes into play. A 40 amp rated circuit would be a minimum install for an EVSE nowdays.

BTW, code also specifies that the cord between the input plug and the EVSE be no longer than 12 inches, so place your new outlet accordingly.

Charles

Note the short cord and plug, you don't want it on the floor, needs to be 4 ft or so up the wall.

leviton-evse-200.jpg
 
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