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I'm out in Chicago and everything is piped in conduit, and my electrician ran 3/4" conduit (100ft run... from one end of my house to other end for an EV outlet). This was 2 years ago, I asked him to install 1" or larger and he doesn't work on larger conduit and I needed to get him out of my basement, so I agreed to 3/4" conduit with a whole bunch of bends. (Guy is a conduit wizard, not an electrical engineer but great price for conduit work and putting in boxes. 10 times faster than me!).

Anyway... I looked up on my phone and I thought I could only put in two, 6 gauge wires in 3/4" conduit, and pulled my two hots through (which much swearing and unhappiness, took me 2 separate pulls in between boxes, and the missus got involved pushing cable. What a pain!).

I'm looking right now, and I guess the fill chart is actually 4, 6 gauge wire.... I took my 3rd 100ft white coil which I thought I would use as a neutral with the NEMA 14-50 plug.

My EV came with a portable EVSE NEMA 14-50 plug, so I put in the NEMA 14-50 plug with no neutral. (Yes, I get why that could be bad for the next guy if he hooks up his RV and expects some 120V lines there; I will change it to a NEMA 6-50 before I leave the house so somebody else knows there isn't a neutral at the plug -- I actually wish I had read the fill chart correctly and pulled the neutral line).

ANYWAY, I get things buttoned up have 6 feet of extra wire on each end of the circuit, and connect everything (safety first) to trial run before I cut the lines.

The EVSE detects I don't have a GND line (since we have conduit), and I add in 6 gauge whip and just touch the metal box (which is tied back to the panel / earth GND). EVSE is not happy with just two hot lines, and evidently does a GND check when it boots up. I did not expect the EVSE to be this smart! Honestly, it is a very good safety decision to make sure there is a valid GND before you can charge 50A. So good on the EVSE company.


What size GND wire would you use for a 50A circuit like that? I have a proposed GND screw + 8 gauge copper wire for the GND? What is code on that...?

In Chicago, electrician/s and code evidently do not require GND wires from 120V outlets to the box (I've been around a bunch of different electricians and houses, and they just don't require GND connections which as an EE seems really strange to me). I guess the assumption is that if something shorts in the box / pipe the breaker will go off.

The EV outlet is in my garage and sure seems like it would require a GFCI (like all the other outlets). I don't really know if the Harry Home Inspector when I go to sell the house would catch this but is the GFCI breaker the right way to have the NEMA 14-50 plug setup?)

Just the way the garage is piped in, the outlet is a bit low, and now the wires are pulled, I'm really set on keeping the 50A line a plug since I spent a Sunday pulling this wire (and 200 ft of 6 gauge is not cheap either).

It wouldn't work to direct wire a wall charger. I'd have to blow out the wall a bit and pipe things in (totally finished garage, etc).

Is the reason people are direct wiring the wall chargers is that your EVSE messes with your 50A breaker? But code is mandating that outlet should be GFCI since it is in your garage?

(I think the moral of the story is I didn't pay very much for the Conduit Wizard, but he didn't really plan this out very well either. Get what you pay for! Having the experience of understanding the plugs and dimensions of the components I would have made sure mounted these boxes at eye level and just done a direct wire for an EVSE, and had him pull 4 conductors with his buddy and save myself a Sunday of misery... ).

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  • Quite a few places require garage receptacles to be GFCI protected. Most GFCI breakers that size are expensive and maybe hard to get, so direct wire EVSE is recommended to bypass GFCI requirements. EVSE's also usually have better GFCIs built in.
    – crip659
    Commented Nov 7, 2022 at 21:31
  • Do you have to go with a plug-in? If you can hardwire the neutral becomes totally unnecessary. Hardwire EVSEs don't even have a connection for it, since the J1772 plug doesn't have a neutral either.
    – KMJ
    Commented Nov 7, 2022 at 22:38

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Wow, just wow... this is a mess of misconceptions on top of all the normal misconceptions circulating in the EV community. I don't even know where to begin. At least the 3/4" EMT is correct.

14-50 is an RV socket not an EV socket

My EV came with a portable EVSE NEMA 14-50 plug,

Imagine you are "on the open road" and you need charging. Let's say it's 2012 when EVs are still rare and there isn't yet built-out charging infrastructure. Where do you find the biggest power that is readily accessible to the public? RV parks. They have fat 14-50's for large RVs.

So if they're tossing in a travel unit to be kept in your trunk for opportunity charging on the road, they'll give you the normal one and the RV socket. They never imagined people would use it as a daily charger; it's not that tough! They expected you'd use a wall unit.

The 14-50 IS NOT an EV socket. It is an RV socket. You should not install a 14-50 simply because travel chargers come with that dongle free and other dongles are $35.

SMH it's not even saving money. The 6-20 dongle + #12 wire is cheaper than #6 wire!

There is nothing wrong with level 2 charging at 15-30A. You do not need to replace 250-300 miles a night, and on that one night you do, there is DC fast charging.

Don't overload your service either

Many people make a lot of fuss to install that giant 50A circuit, but precious few stop to ask "can my house actually handle this?"

The correct way is doing a Load Calculation per NEC Article 220. That will tell you the reserve power available for your house and how much can go to EV charging. Lunging forward and slapping in a 50A circuit in Pavlovian fashion is a good way to damage your panel.

It pays to ask experts before doing/buying

Anyway... I looked up on my phone and I thought I could only put in two, 6 gauge wires in 3/4" conduit

Harper's Law: Buy the wire last. (after asking around for advice). We would have cheerfully told you that THHN in conduit allows 50A on #8 wire.

And those travel units assume 40A anyway, since 40A circuits use the NEMA 14-50 socket. So you could have that + 2 other circuits in the conduit too (derating the #8 to 44A).

The smarter ones would've also told you that 50A is bonkers and set your sights higher than using the free dongles that came with the free travel unit, and that 20A is perfectly adequate... and you wouldn't have believed us and split the difference and gone 30A, and been happy as a clam just like Alec in the above video. (ten years owning three?four? EVs and never used DC fast charging til now). Easy pull and save some coin.

and pulled my two hots through (which much swearing and unhappiness, took me 2 separate pulls in between boxes, and the missus got involved pushing cable. What a pain!).

Well that's inexperience and lack of adequate pulling tools. You'll get better at both. But you also seem to feel you were inconvenienced by having to pull at an intermediate box. Um yeah, you have to use EVERY intermediate access point! (with rare exception you can drag through an access point where it goes straight through not offset; pulling around a curve is out of the question, it'll trash the wire!)

And there can't be more than 360 degrees of bend between access points, the less the better. I aim for 90 (180 if unavoidable). If you were trying to pull around 6 or 8 nineties, no wonder.

My EV came with a portable EVSE NEMA 14-50 plug, so I put in the NEMA 14-50 plug with no neutral. (Yes, I get why that could be bad for the next guy if he hooks up his RV and expects some 120V lines there; I will change it to a NEMA 6-50 before I leave the house

It's illegal to do that. Change it now. Buy the 6-50 dongle. (or just make a 14-50 to 6-50 1-foot-long cheater cord; 1-foot long assures nobody mistakes it for an extension cord and will think before using it). Cheater cords must never cross amp ranges, because an embedded microchip in the dongle tells the EV the safe amperage!

Grounding in EMT-land

ANYWAY, I get things buttoned up have 6 feet of extra wire on each end of the circuit, and connect everything (safety first) to trial run before I cut the lines.

The EVSE detects I don't have a GND line (since we have conduit)

EMT does provide proper ground. The socket didn't have ground because it was dangling; you hadn't mounted it onto the box so it couldn't get ground via the mounting screws. You didn't install a ground jumper wire because you don't need that with EMT.

Just attach it to the mounting box via 1 screw, doesn't even need to be in the box. Or use alligator clip jumper, whatever.

What size GND wire would you use for a 50A circuit like that? I have a proposed GND screw + 8 gauge copper wire for the GND? What is code on that...?

EMT provides the proper ground and no ground wire is required. End of conversation.

If you wanna run a ground, #6 THHN is 65A wire. For 61-100A wire, you need a #8 copper ground. It must be green, yellow w/green stripe, or bare. "But it's a 50A circuit" -> NEC 250.122(B) says you go by the wire size (not directly).

Also it's not "GND". "GND" is a term from low voltage DC electronics, and refers to the common "current return" also called Vss, the negative in most setups. That has bad connotations in AC power, since safety ground is solely a safety shield and should never have current on it. That Vss equivalent is neutral.

In Chicago, electrician/s and code evidently do not require GND wires from 120V outlets to the box

Yes, they do. They certainly do. They only don't require a ground wire if the outlet is able to pick up ground another legal way.

  • it has hard, flush clean-metal contact between metal receptacle yoke and metal box. (so you must get those little "capture the screw" squares outta there).
  • it is UL-listed as "Self-Grounding" meaning it has a wiper to pick up ground off the mounting screw. This applies to the $4-tier "spec grade" receptacles.
  • it is a switch, where the mounting screws are presumed good enough.

But a sharp installer will use one of these methods almost everytime.

GFCI in EVSE-land

The EV outlet is in my garage and sure seems like it would require a GFCI (like all the other outlets). I don't really know if the Harry Home Inspector when I go to sell the house would catch this but is the GFCI breaker the right way to have the NEMA 14-50 plug setup?)

Is the reason people are direct wiring the wall chargers is that your EVSE messes with your 50A breaker? But code is mandating that outlet should be GFCI since it is in your garage?

That thing you call a charger? That's not a charger, it's an EVSE. It has 3 jobs. #1 Be a "smart GFCI". #2 have a relay. #3 send a square wave telling the EV the allowed amps on that circuit.

Do you need a GFCI on a GFCI? No, of course not. That's dumb, and defeats the smart GFCI (auto-retry, and alert user if problem).

But you do need a GFCI on a socket if that socket is in NEC 2020 territory (Chicago isn't yet) and the state hasn't deleted that rule (most have).

So the only reason you would ever need GFCI is because you're insisting on it being a socket. A wall-unit EVSE can be hard-wired, and that will never need a GFCI because it is one.

Hardwired could work though.

It wouldn't work to direct wire a wall charger. I'd have to blow out the wall a bit and pipe things in (totally finished garage, etc).

That's naysaying, you just are worried that you want the ability to rapidly swap EVSEs. That's silly since you perfectly well know how to hardwire. Even if your wall socket is flush-mount, you can stack an extension box on that and then continue with EMT or Legrand Wiremold to a wall-unit EVSE. It's easy to do.

"But it's unsightly" -> No moreso than the cord it would require. The conduit can be painted wall color. Cord can't.

(I think the moral of the story is I didn't pay very much for the Conduit Wizard, but he didn't really plan this out very well either. Get what you pay for!

Are you kidding, Conduit Wizard is the best part of this. Have that guy back. Nobody ever regretted running 3/4" EMT instead of something less.

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  • That's interesting on the outlet making box contact for the ground. Never thought of that. Disagree on the wiring 6 vs 8 gauge and amperage, my time is worth more than the wire costs. I'd rather pull once and have the amperage. Depends on your EV, mine is a baby so 8 gauge and 30amp would be a wash today. Portable evse came with car and a wall mount, that's what I'm using and saving $700 vs a wall mount. Not planning on moving it, I'd DC fast charge out on the road. If conduit wizard had suggested a hardwire I'd have had him layout the boxes. Appreciate the gnd insight!
    – Leroy105
    Commented Nov 8, 2022 at 0:35
  • Where do you find this 'For 61-100A wire, you need a #8 copper ground'? - I bought a 5ft bare copper #8 gauge based on some rando Tesla EV forum to put into the box on the outlet side.
    – Leroy105
    Commented Nov 8, 2022 at 0:41
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    @Leroy105 Ground size from NEC 250.122. Assume every single thing they tell you on EV forums is wrong. My expertise is electrical - while I adore EVs and have been waiting 30 years for this tech to arrive, I'm coming at it from a Code electrical perspective. I have no quarrel with running big wire to the garage - heck I advise #2 aluminum (it's cheaper than #8, and 90A). But then I will turn around and say "commission your EVSE to 20A breaker" if that's all the Load Calc will support. I'm not OCD... I just want insurance to pay. Commented Nov 8, 2022 at 18:40
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    @Leroy105 ILSCO Mac Block Connector is a cheaper Polaris that maxes out at #6. With dual EVs, please use Share2 or equivalent power sharing set to circuit max (65A or less). Two cars charging at "30A" each, guaranteed one will finish by about 2AM, then the other car gets the full 65A or whatever max the EVSE allows. You will need to use a subpanel to split the power to two EVs, since both NEC and UL forbid two EVSEs on 1 circuit, and it's not like they don't know about Share2 - UL specifically approved it. Commented Nov 8, 2022 at 18:44
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    The tricky thing with ground faults @Leroy105 is a rare edge condition where the EV is having a problem and leaks DC current on an AC line. In that case, the DC current will saturate the sense coil on the GFCI, and it won't sense anymore. Some EVSEs (Zappi) will detect DC leakage. Of course a GFCI breaker has no chance of dealing with this. They're pretty limp when it comes to EV protection. On Share2 problems, the "do not overdraw the allocation" must be dog simple and well designed, or UL would not have approved it. Commented Nov 8, 2022 at 22:46

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