Grounding outdoor outlets

[Stan in Oly, WA]

I'm installing an outdoor light on the opposite side of the patio from my house. I'd like to put an outdoor outlet there, too. The power to the new location will be supplied through a 12/2 w/ground underground cable from an existing outdoor light nearer the house. If I had been paying more attention, I would have noticed that light where I'm taking my power is on a 12/2 ungrounded cable.

There is absolutely no way to get an underground ground wire to either location without tearing up so much concrete and brickwork that it's simply not an option. If I had foreseen the problem eighteen months ago, I could have run a ground wire to the distant location with considerable difficulty, but at least it would have been possible then and now it's not. (External conduit won't work---it would literally have to be up in the air.) Also, there is no plumbing in the area to use as a grounding point.

I'm okay for the distant light which will be no worse than the way the existing light is wired (no ground) but I don't know what to do about an outlet. I've thought about putting an ungrounded outlet there so it would not suggest that there was a ground. Is there any other, better way to do this?

Thanks, Stan

 

[old]

Simply drive a ground rod in close by and hook it up. ALL my buildings have a ground rod or 2 at them just so as to make sure every thing always has a ground. If you look you will see that the power company pretty much does the same thing at each and every pole

 

[C.R.]

can you drive a ground rod into the ground by the outlet and hook your outlet ground to that?

 

[Anonymous-0]

Easy way: You don't need one if you use a GFCI outlet. And, they meet code for retrofit on ungrounded circuits.

 

[showcrop]

(quoted from post at 12:22:02 07/17/11) Easy way: You don't need one if you use a GFCI outlet. And, they meet code for retrofit on ungrounded circuits.

en, does a GFCI work without a ground?

 

[John T]

Rich, close but no cigar YES the Utility drives a ground rod (i.e. thats a "made" grounding electrode) at utility poles and uses a grounding electrode conductor like soft bare No 4 Copper wire from the ground rod BUT WHERE YOU THINK THEY ATTACH IT TO ???????????????????????

They attach it to the NEUTRAL !!!!!!!!!!!

If you run a 2 wire (i.e. NO safety equipment groundING conductor, just 1 Hot & 1 Neutral) 120 volt circuit out in say your yard to a receptacle and you drive a ground rod out there and attach it (via a wire) to the third wire green receptacle terminal (i.e. where the bare or green equipment ground would be if it was a 3 wire circuit) THAT WILL MOST LIKELY NOTTTTTTTTT CARRY SUFFICIENT FAULT RETURN CURRENT (Like 20 amps) BACK TO THE PANEL TO TRIP THE BREAKER AND SAVE YOUR LIFE IF THERES A SHORT !!!!!!!!!!!!!!!!!!!!!!!!!!!!!

If that was a 3 wire circuit with a Hot and Neutral and a bare/green safety equipment grounding conductor and there was a short, the equipment ground is there to provide a dedicated low resistance return fault current path back to the panel so the breaker trips de energizing the circuit SAVING YOUR LIFE BUTTTTTTTTTTT mother earth isnt that good of a conductor as compared to copper wire and the breaker likely (depends on a lot of factors) will NOT TRIP.......

So youre indeed right YES the Utility drives ground rods to earth ground the Neutrals buttttttttttttt driving a ground rod out at a receptacle in the yard that only has 2 wires (Hot & Neutral) IS A TOTALLY DIFFERENT THING.

YES youre also right that all buildings require a ground and yes driven rods (made grounding electrodes) can suffice BUTTTTTTTT where you hook it to depends on if you ran 3 wires out there (2 hots and Neutral 120/240) or 4 (2 Hots, Neutral, and Equipment ground

Hope this helps, I did this for a living but longggggggggggg retired lol and a tad rusty on explaining all this

Stay cool next week Rich, its gonna be a scorcher

John T

 

[John T]

Stan, Welllllllllll there are engineering and NEC and safer and proper ways to wire something AND there are ways that will still "work" and it sounds like you just want it to work right???

Okay, outdoor receptacles are supposed to be GFCI protected BUT an non GFCI will still "work"

Okay, its best if you had 3 wire circuits out there (Hot, neutral, Safety Equipment GroundING Conductor) but you dont so were stuck with that I guess.

Sooooooooooooooo if you install a GFCI it will trip in the event theres something like as little as a 5 or 6 milliamps of leakage current i.e. current thats flowing out the Hot but NOT being returned via the Neutral. There could be a short causing the leak and it may wanna return through your old ticker and you dieeeeeeee so if theres leakage current the GFCI senses it and trips de energizing the circuit and you live yayyyyyyyyyyyyyyyy

Get it ??????????????

John T Too long retired electrical design engineer and rusty but believe this to still be true SO NO WARRANTY REMEMEBR

 

[Stan in Oly, WA]

Thanks John. That's what I was afraid of. I had considered driving one or more grounding rods at the location of the new outdoor outlet, but I remembered that you explained on this forum, more than once I think, that a grounding rod or rods would not generally be adequate for this purpose.

Does it make any difference that the ground in this part of the country is probably always wet below the surface layer? Is there a way I could test the grounding capacity of a grounding rod, or is it so unlikely to do what I need it to do that it's not even worth trying? The expense and effort of driving and connecting one or two grounding rods would not discourage me from trying it if there was more than a lottery winning chance that it might work. My alternatives at this point appear to be to install an obsolete style outlet without holes for ground prongs, or not put an outlet there at all.

Thanks for your information.

Stan

 

[Stan in Oly, WA]

Thanks John. Our postings crossed in the mail.

Stan

 

[old]

Ya I did it for a living for years also back when it was all 3 wire stuff not the newer 4 wire stuff. A lot depends on so many variables that ya in theory a ground rod should be enough to make things safe but if it is a hot dry summer that may or may not be true. But also if you live some place like I do and I can dig down 10 feet in most places in this valley and hit water that helps big time

 

[John T]

Hey Stan,,,,,,, Sure, the water and mineral content of good old mother earth all determine its conductivity HOWEVER even if its mineral laden and wet depending, of course, on the distance from the fault ITS PROBABLY STILL TOO RESISTIVE such that the circuit breaker will trip in the event of a fault UNLIKE a copper wire (Safert Equipment groundign conductor) that will indeed return sufficient fault current causing the circuit breaker to trip.......

What about all lay people get confused is how mother earth serves as a common zero reference for the utility Neutral but does NOT serve as a dedicated low resistacne return path for fault current like an equipment grounding conductor. They think you drive 10 rods rods in the ground now all is safe WRONG......driving rods in the ground AND ESPECIALLY if they think you wire them to an outlets safety bare/green terminal and thats a cure all for shorts and faults NOTTTTTTTTTTTTTTTTT

As an attorney and engineer I just hate to advise you to do things wrong and someone gets hurt, but can still say a GFCI is sure a great device wink wink wink as it trips out if theres leakage current lol ID SURE USE ONE ESPECIALLY OUTDOORS and remember it also protects downstream loads (like a light or another receptacle) if they are wired to its load terminals !!!!!!!!!!!!!!!!!!!!

John T

 

[Stan in Oly, WA]

Thanks John. I get it. Plus, I got a good chuckle out of your answer, too.

Still, this is a difficult concept for me. The hardest thing for me to understand is encompassed in this sentence from your last response: "ITS PROBABLY STILL TOO RESISTIVE such that the circuit breaker will trip in the event of a fault UNLIKE a copper wire (Safert Equipment groundign conductor) that will indeed return sufficient fault current causing the circuit breaker to trip......." That makes it seem as if either grounding rods or a copper wire returning fault current will achieve the same result---causing the circuit breaker to trip. If that's the case, in what way is one preferable to the other?

Stan

 

[John T]

MY bad, what I intended to say was mother earth via driven ground rods is a poor conductor i.e. too much resistance, and I doubt 20 amps would get returned thereby tripping a 20 amp breaker HOWEVER if you had a No 12 copper equipment ground (the third bare/green wire) it will return fault current tripping the breaker.

Earth is where all the Neutrals get bonded to try and stabilize the grid its NOT a good enough conductor (too much resistance) to serve as the return path for fault current, thats the job of the third wire bare/green safety equipment groundING conductor..

At the main service entrance panel you drive a rod into earth and bond it to the Neutral.

John T

 

[John T]

Yes

 

[John T]

Thats NOTTTTTTTTTT how its done, see my postings below. The safety equipment groundING conductor is a dedicated low resistance return path for fault current ONLY. Mother earth isnt a good enough conductor, too much resistance. If there was a fault and you tried to use earth via driven ground rods to return fault current to trip the breaker and de energize the circuit to save your life YOURE PROBABLY GONNA DIEEEEEEEEE

John T Retired electrical distribution design engineer

 

[Stan in Oly, WA]

Thanks for taking the time to explain that, John. That cleared it up for me.

Stan

 

[bc]

Stan, I suppose you can't tie on some new wire and pull it through all that brick and concrete?

Another option would be to treat it like a subpanel and add a 20 amp breaker or fuse box at that junction. Then you could drive a ground rod.

Or do the GFCI. I suppose all the outlet will ever see is a bug light, christmas lights, elec weed eater, or a power tool or something slimilar. Most things made to plug in anymore are fairly safe and electrocution isn't all that probable. The GFCI's are prone to easy tripping but you probably won't have that much on it to trip anything. Still beats someone dragging out a 100 feet of #16 extension cord. Good luck.

 

[buickanddeere]

You installed wiring to something in 2010 with a neutral, live line but no ground?

 

[Stan in Oly, WA]

No. In 2010 I ran a direct burial 12/2 w/ground cable from beside the outdoor lamp post where I intended to get power, to a location where I intended to put an outdoor outlet and a light. Then I built a patio over it. Last week when I tried to complete that part of the project, I discovered that my source was supplied by an ungrounded cable and that there was no way now to get a ground wire to either location.

 

[Dusty MI]

I don't know how your old feed cable is laid but here is we did once.

Once we were replacing direct bury parking lot lighting wire with conduit and new wire, all underground. We had started at the far end and working back towards the building, grocery store, from where it was fed.

The feed leaving the building was in a conduit and we expected to find that conduit underground outdoors at the wall. Well the building had been added onto and there was no conduit only wire with concrete around it. Some how they had poured the concrete around the wires leaving the wires loose.

We were able to pull the old wires out one at a time through the sand under that addition. And then hooked the new wires to the last old wire, and pulled them through for the new feed.

Dusty

 

[Stan in Oly, WA]

Hi Dusty,

If I'm in a situation where I have to get a new cable installed, period, then I start trying things that have even a slim chance of working, and leave the worst case solution until last. In this case, I can stay with what I've got and accept that it's a less than ideal outcome.

Between the accessible end of my supply cable in the basement, and the driveway light it powers (the location where I need a ground) is the house's concrete foundation, two concrete retaining walls, and a concrete stairway. The odds against the cable moving freely under all that concrete seem long to me. If I were to try it and damage the cable in the process, my options would be to cut the concrete in the driveway and the basement floor to trench for a new cable, or go without any lighting in front of my house---including what I have now. I'm inclined not to try it.

Stan

 

[C.R.]

ok I knew that was too easy even though it sort of sounds like it could work. a remote ground wont feed back to the distribution pannel because the earth its self isnt a good enough conductor .

 

[Dusty MI]

Stan, your problem just reminded me of that job that I had forgotten about.

Just go with the GFCI. Code allows it in situations like yours.
The test button will not work because there's no ground for it to bleed to for test purposes.

Dusty

 

[bc]

And I think also that the GFCI comes with a sticker to put on it for ungrounded. A notation with a sharpie on the outlet and box wouldn't hurt either or use one of those electric engravers on the box.

 

[buickanddeere]

How about trenching a new cable all the way around from the far side ?

 

[Stan in Oly, WA]

There's nothing but concrete all the way to the street on the side away from the house. At some point in the next couple of years I have to cut through the concrete to dig a trench the length of the driveway (and take out and repour a section of sidewalk) to put in a new water service. At that time I could, with great difficulty and destruction of established shrubs, dig down five or six feet in the planted area above the driveway to come under the retaining wall to bring grounded power to the lights I'm putting in now. But I'm 65, and I'm running out of enthusiasm for those high effort/low return projects I used to always take on with way too little forethought. If the GFCI route gets it done legally, I think I'll do that and count myself lucky that I can do it at all.

Thanks for the suggestion, though.

Stan

 

[Slowpoke]

There are some devices you can attatch to the garden hose and cut a tunnel under the driveway. Or maybe something is made to work on a pressure washer. Search on Ebay for ideas. You might find it is the easiest way to get 12/3 to your outlet. Just be sure to wear foul weather gear!

 

[buickanddeere]

A GFI with a ground rod should be sufficient, depending on the soil type and moisture.
One could almost make a case for a solar panel, battery and inverter at the remote location.