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Discussion Starter · #1 ·
I’ve been searching posts and finding only disagreements about NM-B 12/2 w/Ground cable/wire going through 1/2 inch EMT Conduit. I’ve noticed some people going on about the math, and what I’m doing is about 15 feet inside 1/2 inch EMT Conduit from a non-metal junction box after the NM-B 12/2 w/ground copper building wire ( https://www.cerrowire.com/wp-content/uploads/2019/03/Cerrowire_CerroMax_NMB_Product_Sheet_LR_190322.pdf ) has gone through wood siding from an inside, but not exposed, location of a mountain cabin. The “math” seems to have to do with size of the conduit and bulk of the shielded wires inside, so the 1/2 inch EMT Conduit actually has an inside diameter of .6 inch, and the NM-B is .375 inch wide by .1875 inch thick (3/8 by 3/16). I’m running just the one cable inside the conduit.

The EMT Conduit will be outside, held by brackets against the bottom of the wood siding plank just above the (locally sourced in 1949) stone foundation that is about 4 feet up from the ground. (photo at end of my blathering post) The EMT will turn up and into a non-metallic weatherproof box for a 15 amp GFCI outlet, all covered by an in-use weatherproof locking cover. EMT connectors to the boxes and each other will all be insulated “rain tight” type connectors (compression to the EMT, and lock-nut with rubber washer to the boxes).

I’m obviously not an electrician myself (evidenced even just by how I present this), but this entire DIY project was guided by Home Depot employees who work the electrical department and claim to either have been electricians or know plenty about it. The first electrician at Home Depot put me onto the EMT Conduit based on my question about just adding my power cable to my outdoor outlet by hanging it on the same hooks AT&T’s DSL Line runs. (Told you I’m not an electrician.) I was mainly asking about interference (power cables interfering with the already minimal 5MB data line), and he educated me along the lines of “YOU CAN’T DO THAT,” and the need to run in conduit and use “rain tight” connectors to establish a non-wet situation. (The EMT metal insulating the power wires about 8 inches from the data line should be enough to stop any possible interference was also his thinking.)

All is purchased and now with me at the cabin where there is simply no access to materials without driving more than an hour. The 4 EMT pieces (straight and 90 degree turns) are now painted the color of the cabin, etc. During my numerous hours at Home Depot developing the project I did ask about the outdoors aspect, as well as the “no Romex inside EMT due to overheating” arguments, and I was assured this would all be just fine. There was no assurance that it was “to code,” but just that it would work fine and I won’t have any problems.

I tend to just search for answers at DIY Chatroom because when I do ask questions it seems I get jumped upon for being an idiot or some such attitude, and I’m sure if anyone reads this and comments there will be some of the same NEC Code quotes which seem to sometimes say “yes” and sometimes say “no.” But is there an actual danger at all in this? The wire cable will be fully sheathed beyond the EMT conduit and only stripped away for the connections inside the one weatherproof outlet box. I could even add an extra little awning above the outlet box to protect it some from direct rainfall or snowfall…

The outdoor outlet will not be used too often, and I’m putting it there mainly for 120V charging of a Plug-In vehicle, which takes about 5 hours. Another reason I’m placing the outlet there is that the AT&T equipment does have a ground wire connected to, well… the ground - via an actual stake, and I can ground to that from my outlet. (While the kitchen and bathrooms in this vintage cabin were redone to have grounded outlets, the rest of the cabin is old-school two-wire ungrounded, even for some outlets where they did put 3-pronged outlets - which test as ungrounded… I did change to a GFCI outlet - marking it as ungrounded - for the stereo because I’ve read that’s a good safety move for an ungrounded outlet where doing an actual ground would be a huge pain…)

The circuit I’ll be adding to has a 15 amp circuit breaker at the panel, and like I said I’ll be going with a 15 amp GFCI outlet for the outdoor outlet inside the weatherproof box.

If what I’m doing is not safe because outdoor EMT Conduit, even with “rain tight” connectors and weatherproof boxes, would set up a situation where water could short the wires and turn an open circuit (no electricity running through the wires) into a hot circuit churning with juice that could do damage somehow, could my plan/design be saved by putting an indoor switch prior to the wires going outside that would essentially turn off that outdoor outlet for when it’s not needed?

Any info, advice, or even criticism is welcome! And sorry this has been so long.

Thanks,

Apple
 

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A "Handy Husband"
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The only real code issue is using NM cable in a wet location. Even with rain tight connectors the inside of the EMT is wet due to condensation. If you had used UF cable you would have been compliant. It is not the worse violation by far and I would not be overly concerned with it being unsafe.

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If I'm reading your post correctly, another code issue besides NM in conduit outdoors, you cannot extend an ungrounded circuit even with a GFCI. Connecting it to the phone co stake does not properly ground
 

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A ground rod does not provide a ground for the circuit wiring. You can take a hot wire directly to the rod and it will not trip the breaker.
 
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If I'm reading your post correctly, another code issue besides NM in conduit outdoors, you cannot extend an ungrounded circuit even with a GFCI. Connecting it to the phone co stake does not properly ground
I did not pickup that the circuit you are extending is ungrounded. The is a big code violation. It would be best to run a new circuit back to a dedicated breaker.

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How many amps can your EV pull? 12A (continuous) is considered full capacity for a 15A circuit. Probably you need a dedicated circuit, which would also be legal (not extending an old ungrounded circuit).
 

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Hard to follow the long winded novel.

Can’t extend ungrounded circuit

Best to run a new circuit from panel with ground

You can’t source a ground for an ungrounded circuit from a random ground stake. The ground must come from the panel where it is bonded to neutral at that one point.

If you have crawlspace under cottage would seem easy to run Romex underneath and put weatherproof surface box outside.

Home Depot workers aren’t the best source for electrical advice




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Discussion Starter · #9 ·
THANK YOU ALL! And I'll try to be brief.

While I don't "get" that a stake into the ground can't ground that one outlet (specially if I let go my plan of connecting the NM-B ground wire going back to the garage which I thought could share ground to those outlets), I trust the info about it having to actually ground at the main panel.

I think there is a "save," though. I just tested circuits and I believe I can tap into the one that has grounded outlets (kitchen/bath) and run conduit through the attic, then out and down the outside of the cabin using my painted EMT. (The crawl space under the cabin is very much an "uncrawl" space, sadly.)

I can get 12/2 w/ground UF via Amazon quickly enough and use that instead of the NM-B in the outdoor EMT Conduit. The outlet will be at the front of the cabin, and at the panel that circuit breaker is 20 amps. Probably good to also get from Amazon a 20 amp GFCI for the outlet to power the Plug-In charger (EVSE). And yes, ground isn't only a good idea but the charging cable will not work if ungrounded.

Hope the long-winded novel sequel here wasn't too excruciating, and of course if people who know their stuff (many on DIY Chatroom, not so many at Home Depot) see further problems, do tell. One thing I don't want is to burn our cabin and start a fire in Yosemite!

Rich Apple
 

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Discussion Starter · #11 ·
Kitchen and bath circuit are prohibited from serving other areas of the house.
?? Do you mean the 20 amp panel circuit on which the kitchen/bath GFCIs reside (and other grounded and ungrounded outlets in the kitchen/bath) must not also host other outlets in the cabin? I'd be shocked for this vintage cabin to be "to code," but a few ungrounded outlets in other parts of the cabin are on this 20 amp panel circuit...

My outlet will be "outside the house" (wink wink - I'm sure the code means outside areas of the house too) and I don't see how it would be so different from plugging an outdoor extension cord into the grounded outlet in the kitchen and running it to the charging cable for the car. We did that yesterday.

Sigh.
 

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If you can get into the attic, why not run a new circuit back to the panel?
 

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?? Do you mean the 20 amp panel circuit on which the kitchen/bath GFCIs reside (and other grounded and ungrounded outlets in the kitchen/bath) must not also host other outlets in the cabin? I'd be shocked for this vintage cabin to be "to code," but a few ungrounded outlets in other parts of the cabin are on this 20 amp panel circuit...

My outlet will be "outside the house" (wink wink - I'm sure the code means outside areas of the house too) and I don't see how it would be so different from plugging an outdoor extension cord into the grounded outlet in the kitchen and running it to the charging cable for the car. We did that yesterday.

Sigh.
At the time all those kitchen, bath and other outlets were put on the same circuit, it may have been acceptable according to the code at that time. And under today's code, you can leave it as-is. But if you make changes to that circuit by adding another outlet, then the entire circuit must meet the current code, which says kitchen and bath outlets must be on their own circuits. Adding an outside outlet to that circuit would be in violation of current code.

Using an extension cord is considered a temporary connection and is covered by different sections of the electrical code.
 

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Let me explain why grounding to a ground rod is not sufficient for a properly grounded receptacle. The resistance of a ground rod might be 20 ohms (on a good day and it is probably more). If you have a ground fault (hot wire crossed with ground wire or anything connected to it), current will flow. Ohm's law says the current {I} will equal the voltage {E} divided by the resistance {R).

I=E/R = 120 / 20 = 6 amps

This current will flow forever and not trip a 15 or 20 amp breaker.

A properly ground receptacle has the ground wire connected back to the service neutral at the breaker panel. The resistance is 1 ohm or less.

I= E/R = 120/1 = 120 amps This will trip the breaker instantly.

The purpose of a ground rod is for lightning protection and its value at best is questionable.
 
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Discussion Starter · #15 ·
Let me explain why grounding to a ground rod is not sufficient for a properly grounded receptacle. The resistance of a ground rod might be 20 ohms (on a good day and it is probably more). If you have a ground fault (hot wire crossed with ground wire or anything connected to it), current will flow. Ohm's law says the current {I} will equal the voltage {E} divided by the resistance {R).

I=E/R = 120 / 20 = 6 amps

This current will flow forever and not trip a 15 or 20 amp breaker.

A properly ground receptacle has the ground wire connected back to the service neutral at the breaker panel. The resistance is 1 ohm or less.

I= E/R = 120/1 = 120 amps This will trip the breaker instantly.

The purpose of a ground rod is for lightning protection and its value at best is questionable.
thank you again, rjniles... Would the main panel have to have the "service neutral" ground within it? I ask because the main panel does have a conduit coming down from it connected to a ground rod just like the AT&T one on the other side of the cabin. I test my outlets for ground using a little orange plug by Klein (RT210) and while it shows Open Ground, reversed circuits, etc. it does simply report "Correct" for the kitchen and bath GFCI and other grounded outlets. I'm worried that the high resistance ground rod for the panel might look like a good ground to the Klein device? A real electrician wouldn't have ever done something like that (ground rod only), eh?

Hopefully the outside rod into the ground is just something additional on the panel for additional lightening protection (or so intended).

The panel doesn't have any open places to add a circuit, but there is another 20 amp circuit that serves just the washing machine, and that outlet tests as "correct" for ground. Perhaps adding my outside outlet to that circuit and running through the attic is an option that would not even be a code violation?

Thx
 

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I hate to give you more bad news, the laundry is another dedicated circuit. A code violation to use that circuit outside that location.

You panel may be full but be rated for tandem breakers. Tell us the manufacturer and model number of the panel. A picture would also help.

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There is a difference between system grounding and equipment grounding for receptacles. Entirely different functions.
 

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Discussion Starter · #18 ·
Jim Port - Thanks. So the rod to the earth is the System Ground and the Equipment Ground is what the actual grounded outlets are enjoying via the panel.

rjniles - thanks again (for the bad news) but I'm guessing unless I do anything to the circuit, the actual washer/laundry not being on a dedicated circuit is not a code violation. It is with the kitchen outlets that are all grounded, and while I do trace a grounded cable from the panel doing just one thing and is 20 amp, that is the outlet the Refrigerator is plugged into. And the fridge has gotta be one of those "required to be dedicated."

The panel has "Washer" written next to a single-throw 20 amp (#8 - second from bottom on the right) and it's not the laundry washer, the dishwasher, or anything I've found. I've not mapped it to anything yet, but maybe that can still be my circuit!

In the one photo the "Washer" and "Bath GFI" are both off, but just for now. The unit is a Square D All In One, Series M01 - catalog number SO1020M1008. Googling Tandem Breakers, for the two switches in one slot should I go back to my mapping of my circuits switching them singularly? I only have switched the tandems together! If I can find one of the 20 amp switches that is not for kitchen, bath, or anything I can't junction into, perhaps that will be the ticket. Also perhaps the Washer is on a dedicated circuit...

Photos such as they are... Thanks!
 

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A "Handy Husband"
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The second from the bottom breaker on the right side could be replaced with a tandem to give you the additional circuit.

Or the breaker labeled refrigerator could be replaced by a tandem.

the 30 amp breaker below the service disconnect 100 amp is a concern: it is labeled dryer+ stove??
 
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The refrigerator does not require a dedicated circuit.

A tandem is two breakers or circuits in the space of one single pole breaker. They control two loads.
 
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