14-50 passthough ground OK or pigtail required by NEC?

[stopcrazypp]

I am going to install a 14-50 given my free supercharger usage is about to expire. It's a fairly straight forward install as I have a existing surface mounted subpanel in my garage with the free capacity and the receptacle outlet box will just be surface mounted and right at the bottom of the subpanel.

A question I had is if a pass through ground connection to the outlet box as below would be ok and satisfy NEC or would I have to do the traditional 3 wire pigtail connection with a wingnut?

Are pass-through grounding screw connections allowed by the NEC?

Traditional example here just from a regular outlet from reference (notice there is pigtail to the ground screw):

My dad does not like doing the wire nut connection and feels it makes for a less secure connection than just the wire passing through the ground screw (and the ground screw connection he feels isn't even necessary in the first place in our case anyways given the outlet box is grounded via the EMT connection).

PS: I notice in a lot of videos that I looked up that people don't even do any connection to the ground screw at all when installing a 14-50, it seems people are relying on the receptacle mount screws to pass through the ground to the outlet box.

However, I would rather do everything by NEC so that if I decide to do an inspection (when covid hopefully dies down), I don't run into trouble.

I'm even going to install a 50A GFCI breaker, but finding it is very hard to find the ones that are UL listed to my Eaton BR subpanel, namely breaker models GFCB250 or GFTCB250 (which apparently is required to meet NEC, can't just install one that fits). It is not carried any longer at Home Depot or Lowes. From asking stores that list it, lead time is 3-6 weeks if I want to order a new one at a reasonable price ($110-120), the ones that have them in stock are charging over $250, which is ridiculous. Now I understand why some electricians say there is a long lead time for these breakers or it costs $200+, you can't just go to a store and buy any one that fits. I guess I'm going to have to use a regular $15 50A Eaton BR breaker in the meantime while waiting for the GFCI one to arrive or use my dryer connection (which I tested working fine).

I'm in the Bay Area in California BTW if that changes anything.

 

[Sophias_dad]

Assuming you are using 10AWG as your ground line, you can be very sure that one of these is NEC compliant...

Commercial Electric Winged Wire Connectors, Green (15-Pack)-778307 - The Home Depot

Green Winged Wire Connectors are designed to make electrical ground connections. With a feed through hole in the top of the connector, this specialty grounding only connector allows for 1 wire to be extended

www.homedepot.com

It allows pass-through of the original wire unimpeded and an additional 10 AWG ground line back to the screw. Since its only 10 AWG, I'd avoid using stranded wires. I'm not a big fan of stranded wires under screws because they tend to splay unless done well.

 

[stopcrazypp]

Assuming you are using 10AWG as your ground line, you can be very sure that one of these is NEC compliant...

Commercial Electric Winged Wire Connectors, Green (15-Pack)-778307 - The Home Depot

Green Winged Wire Connectors are designed to make electrical ground connections. With a feed through hole in the top of the connector, this specialty grounding only connector allows for 1 wire to be extended

www.homedepot.com

It allows pass-through of the original wire unimpeded and an additional 10 AWG ground line back to the screw. Since its only 10 AWG, I'd avoid using stranded wires. I'm not a big fan of stranded wires under screws because they tend to splay unless done well.

I'm going to use 10AWG for ground, haven't decided on stranded or solid yet. Yeah, maybe I'll just go with that style of wingnut, looks like it'll address both concerns.

 

[Jeremy3292]

Since it is a metal(lic) box, you need to ground the box by wrapping the ground wire around the green screw (as showed above in your picture) before attaching the ground wire to the outlet. You do not need a green wire nut at all bc it is a dedicated circuit. If you were daisy chaining multiple outlets together on the same circuit, that would require the green wire nut (to daisy chain the ground wires of multiple outlets together) and the green screw.

Simply using the green ground nut with the passthrough hole at the top shown above by @Sophias_dad is also perfectly fine as it shows without a doubt that “this is the ground wire”. There is only one ground wire so there is nothing to wire nut together on a dedicated circuit.

The only technical question I would have is does the NEC require a separate couple inch ground wire to be connected to the green screw? That would then require a green wire nut.

 

[Jeremy3292]

this would be an example…now simply connect the wires to your outlet IMO

 

[stopcrazypp]

Since it is a metal(lic) box, you need to ground the box by wrapping the ground wire around the green screw (as showed above in your picture) before attaching the ground wire to the outlet. You do not need a green wire nut at all bc it is a dedicated circuit. If you were daisy chaining multiple outlets together on the same circuit, that would require the green wire nut (to daisy chain the ground wires of multiple outlets together) and the green screw.

Simply using the green ground nut with the passthrough hole at the top shown above by @Sophias_dad is also perfectly fine as it shows without a doubt that “this is the ground wire”. There is only one ground wire so there is nothing to wire nut together on a dedicated circuit.

The only technical question I would have is does the NEC require a separate couple inch ground wire to be connected to the green screw? That would then require a green wire nut.

The latter part is exactly the same question I had. I know electrically, wrapping the ground wire around the screw already achieves the same function as a pigtail, but the question really is if NEC requires a separate wire connected to the green screw in this situation? I know this is commonly done in most outlets, but it's because as you say, you when you are daisy chaining multiple outlets (which does not apply in this case), having a pigtail is the only practical way to do it.

I guess I can use the green nut with the passthrough hole just to be safe, as it is explicitly NEC approved.

 

[Jeremy3292]

The latter part is exactly the same question I had. I know electrically, wrapping the ground wire around the screw already achieves the same function as a pigtail, but the question really is if NEC requires a separate wire connected to the green screw in this situation? I know this is commonly done in most outlets, but it's because as you say, you when you are daisy chaining multiple outlets (which does not apply in this case), having a pigtail is the only practical way to do it.

I guess I can use the green nut with the passthrough hole just to be safe, as it is explicitly NEC approved.

My thoughts exactly. Just use the green wire screw, then pass the ground wire through the green wire nut, and then connect to the outlet.

 

[Frank99]

Hopefully one of our knowledgeable electricians drop in. I’m an accomplished amateur, and have opinions on whether what you’re asking about is safe (I don’t see a problem with it), but not whether it’s code compliant. Interested to get an authoritative answer.

 

[earthwormjim]

You do not need the wirenut, that wirenut is used for convenience because there are other circuits downstream, and EMT was not used in your picture. It's not a requirement in code that you have a bunch of ground wires wire-nutted together in every junction box. Those grounds could have been crimped together or screwed into the junction box, but that's really awkward to do by comparison.

By NEC standards, all of those grounds are one piece of exposed metal, so the wirenut isn't doing anything special here, that a screw or crimp couldn't do.

Contractors have bags of wire nuts on hand, so that's what they always use. Probably every junction box had someone outside the house build, put in a short length of ground wire and screwed that into place, and at the same time knocked out the holes that would be needed. That way every junction box was setup for easy installation.

Since you are using EMT, you do not even need to run a ground wire next to your other wires, your junction box and conduit are your safety ground. You can directly wire the ground lead from your outlet, to the ground screw on your junction box. Definitely run a ground wire from the outlet to the ground screw though, don't just rely on the outlet housing screws.

If you haven't bought your wire yet, save some money on ground wire since you don't need it for the actual wire run, just a short amount for within the outlet.

By the way, please use Wago style (gen 2 clear ones) clips for connections, not wirenuts. Far easier to use, and impossible to screw up.

 

[rwiegand]

Since you are using EMT, you do not even need to run a ground wire next to your other wires, your junction box and conduit are your safety ground. You can directly wire the ground lead from your outlet, to the ground screw on your junction box. Definitely run a ground wire from the outlet to the ground screw though, don't just rely on the outlet housing screws.

Perhaps using the conduit as ground is OK in your jurisdiction, it wouldn't fly here (MA). Too much danger of a broken connection somewhere along the line. Using the outlet housing screws wouldn't pass muster anywhere in the US, AFAIK.

 

[stopcrazypp]

You do not need the wirenut, that wirenut is used for convenience because there are other circuits downstream, and EMT was not used in your picture. It's not a requirement in code that you have a bunch of ground wires wire-nutted together in every junction box. Those grounds could have been crimped together or screwed into the junction box, but that's really awkward to do by comparison.

By NEC standards, all of those grounds are one piece of exposed metal, so the wirenut isn't doing anything special here, that a screw or crimp couldn't do.

Contractors have bags of wire nuts on hand, so that's what they always use. Probably every junction box had someone outside the house build, put in a short length of ground wire and screwed that into place, and at the same time knocked out the holes that would be needed. That way every junction box was setup for easy installation.

Since you are using EMT, you do not even need to run a ground wire next to your other wires, your junction box and conduit are your safety ground. You can directly wire the ground lead from your outlet, to the ground screw on your junction box. Definitely run a ground wire from the outlet to the ground screw though, don't just rely on the outlet housing screws.

If you haven't bought your wire yet, save some money on ground wire since you don't need it for the actual wire run, just a short amount for within the outlet.

By the way, please use Wago style (gen 2 clear ones) clips for connections, not wirenuts. Far easier to use, and impossible to screw up.

Given the outlet is right under the subpanel, there is really no practical cost difference to have the ground wire, so I'm just going to use one, I do see in the subpanel that whoever installed it used grounding bushings for the ground connections to other circuits in lieu of a ground wire through the conduit, so I suppose this is allowed in my jurisdiction.

 

[earthwormjim]

Perhaps using the conduit as ground is OK in your jurisdiction, it wouldn't fly here (MA). Too much danger of a broken connection somewhere along the line. Using the outlet housing screws wouldn't pass muster anywhere in the US, AFAIK.

What you said honestly doesn't make any sense and will just confuse people. The reason to even use EMT is it can act as a ground, otherwise non-metal conduit can be used and is cheaper. It's perfectly valid according to NEC to use EMT as a ground. The idea of a broken connection is just as unlikely as a ground wire having a broken connection.

Brief check of MA code states that EMT is:

Electrical Metallic Tubing (EMT). An unthreaded thinwall raceway of circular cross section designed for the physical protection and routing of conductors and cables and for use as an equipment grounding conductor when installed utilizing appropriate fittings.

358.60 Grounding

EMT shall be permitted as an equipment grounding conductor.

The only restrictions I know of are when the length of EMT is so long it leads to a very high resistance. You will never encounter that scenario in a house though.

Outlet housing screws are perfectly fine as a ground provided it is a self grounding receptacle, but as I clearly stated, I wouldn't do that and would use an actual ground wire.

 

[rwiegand]

I know that EMT should work just fine as an equipment ground if properly installed and continuous and that it is allowed, and I know that our town inspector won't sign the card (at least for homeowner installed wiring) unless there is a grounding wire inside that conduit. Guess who wins.