[PDX_Dude]

Howdy, folks! I'm new to this forum but not to DIY My question concerns installation of a 240V receptacle in a garage. This will be used for an EV charger, which requires only 240V, hence I chose NEMA 6-50.

My current set-up includes a standard 200A flush mount electrical panel in the garage. It still has 6 available spaces, so installing a 50A 2-pole breaker is not a problem. I want to install a flush mount receptacle and run all wiring inside the wall. I have a 3/4" flexible metal conduit (FMC), so I figured I can just get 6-gauge THHN/THWN wires by the foot from Home Depot and run them inside this FMC. The FMC will be connected to the electrical panel on one end and to a 2-gang electrical box on the other. I want to install everything according to the NEC, so I have a few questions:

1. The panel is nested in between two studs, so in order to use one of the side knockouts, I will have to drill a hole in a stud. Can I do that (legally) or should I just use a top/bottom knockout instead?
2. In the future, I may want to replace this receptacle with NEMA 14-50, which requires a neutral. Can I run a neutral inside the same conduit and then terminate it with a cap/electrical tape/heat shrink in the receptacle box?
3. If the answer to question 2 is yes, then I would need to run 4 wires in the conduit (2 hots, a neutral and a ground). The conduit is not big enough for 4 wires, so I am thinking to use the FMC itself as a ground conductor. It is less than 6', hence it shouldn't violate the code. My only concern is how strong a contact between the FMC and the panel will be. The panel is painted, so the only exposed grounded metal is the edges of the knockout itself. Will this be enough?

Your feedback would be greatly appreciated!

 

[Oso954]

Why go with a 6-50 now if you think you want a 14-50 later ?

I’d install the 14-50 now with 4 conductors. Solves the grounding issue. Almost any EV charger with a 50 amp Power cord is available with the 14-50 plug.

 

[brric]

For grounding purposes, conductors within FMC must be protected at no more than 20 amps. NEC 250.118(5)b

 

[PDX_Dude]

Why go with a 6-50 now if you think you want a 14-50 later ?

I’d install the 14-50 now with 4 conductors. Solves the grounding issue. Almost any EV charger with a 50 amp Power cord is available with the 14-50 plug.

Let's just say I have some parts that I bought for another project that never happened. I do have a 6-50R, a 6-50P and another 6-50 "exterior" socket/receptacle (don't know how it's called properly). Then, I have four 6-ft 6-gauge wires (green, black, red and white). And I have an FMC. So, as you can see, I will be saving quite a few bucks if I go with NEMA 6-50 :smile:

 

[PDX_Dude]

For grounding purposes, conductors within FMC must be protected at no more than 20 amps. NEC 250.118(5)b

I guess my comprehension skills are lacking today. Does it mean I cannot use FMC as a ground for conductors carrying more than 20 Amps? That would be a bummer, as it would mean no neutral for future upgrade.

 

[Kevin_Essiambre]

I guess my comprehension skills are lacking today. Does it mean I cannot use FMC as a ground for conductors carrying more than 20 Amps? That would be a bummer, as it would mean no neutral for future upgrade.

That is what he is saying.

Now, considering its only a 6 foot run (max), you could leave out the neutral for now, and cross that bridge when you want to install the 14-50R...

Sent from my new phone. Autocorrect may have changed stuff.

 

[PDX_Dude]

That is what he is saying.

Cool -- that would answer questions 2 and 3. Now, I hope someone can clarify if I can drill a hole in the frame to get access to an adjoining knockout.

 

[Kevin_Essiambre]

Cool -- that would answer questions 2 and 3. Now, I hope someone can clarify if I can drill a hole in the frame to get access to an adjoining knockout.

I'll admit that I've drilled the stud beside a panel to get wiring into it... hundreds of times.

I don't really see an issue.

Try not to remove more than 1/3 of the stud, and try to stay center in the stud.

This will usually mean use the knockouts towards the back. They are usually more centered to the stud.

I use a holesaw to remove material where needed. Depending on the connector you use, you may need to notch the stud for the set screw on the connector.

Use a holesaw large enough to fit the whole connector. Most studs I've drilled were 2x6, so i could make plenty big enough holes, and even with a 2x4, a 1.25" hole should be plenty.

Measure and mark where to drill. Depending on where you will enter the panel, sometimes you can drill a 1/4" hole from inside the panel to locate the center of your knockout.

**I am not up on current building codes, I assume no liability for this advice!**

Sent from my new phone. Autocorrect may have changed stuff.

 

[rjniles]

4 #6 in 3/4 FMC is 38% fill. You can use a #10 ground.

Sent from my Moto E (4) Plus using Tapatalk

 

[seharper]

I have a 3/4" flexible metal conduit (FMC), so I figured I can just get 6-gauge THHN/THWN wires by the foot from Home Depot and run them inside this FMC.

Does you receptacle only have 60C terminations? That would be the only reason to use #6 wire. #8 wire is acceptable for 50A as long as everything is rated 75C.

[*] The panel is nested in between two studs, so in order to use one of the side knockouts, I will have to drill a hole in a stud. Can I do that (legally) or should I just use a top/bottom knockout instead?

Yes, if you can figure out how to use proper hardware. A nipple of Rigid might help.

[*]In the future, I may want to replace this receptacle with NEMA 14-50, which requires a neutral. Can I run a neutral inside the same conduit and then terminate it with a cap/electrical tape/heat shrink in the receptacle box?

Yeah that's fine, you can do that right now.

[*]If the answer to question 2 is yes, then I would need to run 4 wires in the conduit (2 hots, a neutral and a ground). The conduit is not big enough for 4 wires

That's not true. 3/4 FMC is good for either four #6 or four #8. However you only need #10 for your ground wire.

, so I am thinking to use the FMC itself as a ground conductor. It is less than 6', hence it shouldn't violate the code. My only concern is how strong a contact between the FMC and the panel will be. The panel is painted, so the only exposed grounded metal is the edges of the knockout itself. Will this be enough?

That's not the problem. The problem is that your "through the stud" strat will make it very difficult to use a proper FMC fitting in the normal, tightened/bolted/clamped contact manner in which it's meant to be used. Just having the FMC brush into the hole as it enters the box isn't going to cut it.

Also what brric says.

 

[PDX_Dude]

Thanks, everyone! Your replies were very helpful :thumbsup:

 

[PDX_Dude]

I finally had some time to go ahead with this project. I had to modify my initial plan due to the fact that there was a double stud where I wanted to drill to a side knockout. So, I ended up using one on the bottom. I used two #6 for the hots and #10 for the ground. The FMC turned out to be only 1/2", so that's all I could do not to exceed 40% fill anyway. I am attaching some pics of the installation — could you please point out some obvious errors or code violations? Thanks!