Questions about outside outlet

[Jerry Bruette]

1. Is there a limit on how far away an outlet can be from the GFCI that controls it?

2. If I want to put the outlet on a post how far above grade does the box have to be?

I would like to extend a buried line about 75 feet from a GFCI outlet and mount a weather tight box on a 4x4 post. Is the 75 feet allowable and how far above grade should the box be?

[Paul F Franklin]

There's no code limit as to how far a receptacle can be from a GFCI that controls it, but as a practical matter, you are better off putting a second GFCI at the remote location, so when it trips, you don't have to walk all the way back to reset it. And, no, it doesn't matter if the remote GFCI is connected to the load or line side of the first GFCI, but one would typically connect it to the line side.

There's no code minimum for height above grade for an outdoor receptacle. But keep it high enough so it doesn't get flooded. If you anticipate using it in winter, keep it above typical snow depth.

You will need an "in-use" cover. I find that wasps love to build nests inside the type of in-use cover that has opening on the bottom that are always open, so I use the style that has no openings when it is not actually in use.

75 feet is no issue, but if you see yourself using the outlet for heavy loads like a compressor or larger power tools, I'd probably run 10 ga wire to minimize the voltage drop.

[Cameron Wood]

I agree with Paul above, except for this and the 10 ga comment:

"And, no, it doesn't matter if the remote GFCI is connected to the load or line side of the first GFCI, but one would typically connect it to the line side."

If the remote outlet is connected to the line side of the GFCI, it will not be GFCI protected. I hope this was a typo or something.


I find weatherproof outlets mounted lower than 24" to be super annoying- hard to access.

[Jim Koepke]

I agree with Paul above, except for this and the 10 ga comment:

"And, no, it doesn't matter if the remote GFCI is connected to the load or line side of the first GFCI, but one would typically connect it to the line side."

If the remote outlet is connected to the line side of the GFCI, it will not be GFCI protected. I hope this was a typo or something.


I find weatherproof outlets mounted lower than 24" to be super annoying- hard to access.

I think Paul was saying the receptacle on the extended location should be a GFCI receptacle as opposed to using the current GFCI for protection.

jtk

[glenn bradley]

I would query "the city" if you don't have access to the version of the NEC they are using. My recent build just slipped under the wire or I would have had to add many AFCI outlets and breakers to my shop. Using a GFCI as protection for additional downstream outlets has become pretty restricted around here. If you are going to ignore "code" I would just extend it and move on.

[Jim Becker]

I agree with Paul above, except for this and the 10 ga comment:

"And, no, it doesn't matter if the remote GFCI is connected to the load or line side of the first GFCI, but one would typically connect it to the line side."

If the remote outlet is connected to the line side of the GFCI, it will not be GFCI protected. I hope this was a typo or something.


I find weatherproof outlets mounted lower than 24" to be super annoying- hard to access.

The part you quoted was specifically about the OP putting an actual GFCI at the remote box, so yes, it would be protected with either connection method.

[Charlie Velasquez]

I agree with Paul above, except for this and the 10 ga comment:

"And, no, it doesn't matter if the remote GFCI is connected12 to the load or line side of the first GFCI, but one would typically connect it to the line side."

If the remote outlet is connected to the line side of the GFCI, it will not be GFCI protected. I hope this was a typo or something.


I find weatherproof outlets mounted lower than 24" to be super annoying- hard to access.

Also, whether your extension conductor is gfci protected before or at the the end outlet will affect the method you use to run those conductors.

If the extension conductor is not gfci protected till it gets to the last outlet you will need to bury it 18” in conduit or 24” direct bury (or 6” in rigid conduit, but who would do that for 75’.)
If hooked to the load side of the feeding gfci outlet, you can use uf cable and direct bury it at 12” depth. That may make your job a lot easier.

[Charlie Velasquez]

Additionally, Your conductors must be protected from physical damage, which suggests you will need to have at least a conduit sleeve from below grade to your feeder junction box and another sleeve at your remote box.

Frostline in Peshtigo is… 62” ?
Assuming you are not going to bury your 4x4 that deep. If your conductors and post are not buried to the same depth you may have an issue with differing heave amounts. You will need some way to deal with that; either an expansion fitting on your conduit or a flexible piece of conduit. You almost will assuredly need one at your feeder site if it is on your house.

[Cameron Wood]

OK, that makes more sense, but a GFCI downstream from another GFCI is not good practice- I've seen that malfunction.

[Bill Dufour]

I prefer to mount the master GFCI indoors out of the weather or at least under the house eaves. I had one that got rainwater in and things got rusty. Who knows if it would have worked or not?
Bill D

[Jerry Bruette]

Also, whether your extension conductor is gfci protected before or at the the end outlet will affect the method you use to run those conductors.

If the extension conductor is not gfci protected till it gets to the last outlet you will need to bury it 18” in conduit or 24” direct bury (or 6” in rigid conduit, but who would do that for 75’.)
If hooked to the load side of the feeding gfci outlet, you can use uf cable and direct bury it at 12” depth. That may make your job a lot easier.


Additionally, Your conductors must be protected from physical damage, which suggests you will need to have at least a conduit sleeve from below grade to your feeder junction box and another sleeve at your remote box.

Frostline in Peshtigo is… 62” ?
Assuming you are not going to bury your 4x4 that deep. If your conductors and post are not buried to the same depth you may have an issue with differing heave amounts. You will need some way to deal with that; either an expansion fitting on your conduit or a flexible piece of conduit. You almost will assuredly need one at your feeder site if it is on your house.

Charlie thanks for replying to my question. Here's a poor drawing of what I want to accomplish. I have the conduit and wire purchased and I'd like to go that route in case something goes wrong with the system I can pull new wire. I only have about 3 feet from grade to ledge rock where I want to run the conduit so you're right I won't be burying anything at 62". How deep should I bury the conduit?

504790

[Charlie Velasquez]

18”
Assuming thwn conductors?

[Thomas McCurnin]

A GFI breaker in the service panel, when tripped, will of course turn off all outside receptacles governed by the GFI. I find that really annoying, because one cannot determine which receptacle is shorting out. Therefore, put an ordinary breaker in the service panel and a GFI receptacle for each outside line. 75 feet is quite a distance and you will have voltage drop. Going from 12 gauge to an 8 or a 10 would be wise. There are specific calculations for voltage drop which will depend on the amps being sent through the wire and the length. Any qualified electrician will have these tables or they are on line. Your local code will also inform you how deep to bury the lines, but typically that number is around 18-24 inches. I'd put them in the grey pvc schedule 80 and yes, I find having the covered box a couple feet off the ground makes it easier to open the box and insert the plug.

[Jerry Bruette]

18”
Assuming thwn conductors?

Thanks and yup

[Cameron Wood]

A GFI breaker in the service panel, when tripped, will of course turn off all outside receptacles governed by the GFI. I find that really annoying, because one cannot determine which receptacle is shorting out. Therefore, put an ordinary breaker in the service panel and a GFI receptacle for each outside line. 75 feet is quite a distance and you will have voltage drop. Going from 12 gauge to an 8 or a 10 would be wise. There are specific calculations for voltage drop which will depend on the amps being sent through the wire and the length. Any qualified electrician will have these tables or they are on line. Your local code will also inform you how deep to bury the lines, but typically that number is around 18-24 inches. I'd put them in the grey pvc schedule 80 and yes, I find having the covered box a couple feet off the ground makes it easier to open the box and insert the plug.




Many houses, including mine, have 75' or more from the panel to far convenience outlets. How many of them have larger than #12 wire? None, I'd wager.

The OP's use is not mentioned, but standard GFCI recepticals are rated at 15 amps. #8 wire in conduit in earth is rated about 60 amps.

Voltage drop for 75' of #12 wire at 10 amps would be a little over 3%; for #8 wire it would be about 1%.

[Jim Koepke]

There are calculators for such things > https://www.calculator.net/voltage-drop-calculator.html

jtk

[Jim Becker]

The OP's use is not mentioned, but standard GFCI recepticals are rated at 15 amps..

There are also 20 amp rated GFCI outlets available for additional shekels...

[Thomas McCurnin]

Unless the receptacle if for light tools or lighting, both the cable size and the receptacle should match the breaker size, e.g., with a 20a breaker, assume a 20a load, and a 20a receptacle. Anything less, is inviting trouble. By the way, some power tools are particularly susceptible to voltage loss, like my 20a Hilti power shovel. It will overheat and just shut down if used with a 100' undersize extension cord. Electric welders have similar finicky problems.

[Cameron Wood]

Hilti's biggest (I believe) breaker, at 60 lbs, is rated at 15 amps. If you have trouble running it on a 100' #14 extension cord, OK,

but suggesting running #8 wire to a convenience outlet in the yard is ridiculous. I ran that recently for a 240v 40 amp hot tub.


(sorry, feeling grumpy tonight)

[Maurice Mcmurry]

When GFI's were a new requirement and cost $25 a builder in our town would only buy one and use it to protect all of the required outlets in the whole house. At that time a 250 foot roll of Romex was $12. What a thrifty guy! His approach passed inspections. It took me a while to learn how to troubleshoot those houses.

[Charlie Velasquez]

18”
Assuming thwn conductors?
Need to qualify my answer.
I was assuming you would follow the advice of the other members wrt running those conductors from pigtails from the line side of the gfci outlet.
If you run it from the load side of that outlet and your conductors are gfci protected all the way there you can use the 12” depth.

[Steve Demuth]

Hilti's biggest (I believe) breaker, at 60 lbs, is rated at 15 amps. If you have trouble running it on a 100' #14 extension cord, OK,

but suggesting running #8 wire to a convenience outlet in the yard is ridiculous. I ran that recently for a 240v 40 amp hot tub.


(sorry, feeling grumpy tonight)

I agree. I don't know where you'd even find a 15A receptacle that would accomodate #8 wire.

[Bill George]

I agree. I don't know where you'd even find a 15A receptacle that would accomodate #8 wire.

Plus if you did a Voltage Drop calculation you will find even drawing a full 20 amps on #12 AWG wire on 100 ft you will find little or no reason to go larger on the wire. Thats all I use #12 wire and 20 amp rated outlets. Plus unless they have changed the Code its a Minium of 18 inches on all buried wire.

505433505434

[Charlie Velasquez]

….. Plus unless they have changed the Code it’s a Minium of 18 inches on all buried wire.


Rigid = 6”
protected by 2” or more of concrete is less than 18”
gfci protected = 12”
505510

[Bill George]

But local Code can require deeper. Yes you are correct and when was that changed? Because if the depth was to avoid damage to the conductors it does not make sense?

[Scott Winners]

My one contribution here, in agreement with most, is to err on the side of caution. When a GFCI trips, there might be enough capacitance, enough current, stored in just the cable to make a mess of delicate things like fingertips.

I personally would use a GFCI doohickey at every junction. Planting posts and burying wire below the local frostline counts as "in a workmanlike manner" in my book. I did read where the OP was located when I started reading this thread, but I don't remember now on page 2.

With no outpatient followup like OP wound care or OP prescriptions, just showing up at your local ER with a minor to moderate electrical burn is going to be $5-10K before insurance coverage. Let this knowledge inform your materials purchases and trench depth.

Electrical infrastructure is one of those "buy once/ cry once" sorts of things, though outdoor electrical does add a level of sophistication. If you do good work now that meets current code it should be safe and fine after it has to be grandfathered in by your own grandchildren, as long as the current draw on our circuits doesn't change.

In the late 1990s I had no problem running 75 feet on buried 12AWG/20 amps/ 110-120 volts with GFCI at every connection. I don't know if that meets current NEC, but the outlets I did run are probably fine. Except for the above ground connections. Out in the weather you got to open your best possible jiffy boxes every couple years to look for oxidation, corrosion, and impending failure. And test them, twice annually. Every spring and every fall hit the 'test' button on your GFCIs to make sure they are still working. You may have an ice cold gin and tonic in one hand while you are pushing the test and reset buttons with the other hand, but everyone with outdoor circuits has some obligation to maintain them.

[Steve Demuth]

Planting posts and burying wire below the local frostline counts as "in a workmanlike manner" in my book. I did read where the OP was located when I started reading this thread, but I don't remember now on page 2.

Frost depth here in NE Iowa easily reaches 48" some years. To be safely below frost, as for a water line, e.g., you need to be at a minimum of 5'. No one to my knowledge buries electrical lines that deep - not the 14.4kv lines from the overhead grid to your transformer, not the service entry from the transformer to a building, and not for outdoor outlets or appliances.

I can't imagine where you are, anybody goes below frost either (and in many areas not far from you, you obviously can't, since the frost goes down dozens of feet).

[Scott Winners]

In my experience the trouble with outdoor circuits is freezing/frozen ground lifting the posts up out of the ground. The cable is going to be fine, but as your posts lift up winter after winter and year after year, perhaps a fraction of an inch each year, it will still add up over time.

For my mail box post I dug a I think a 36" hole, then 4" of gravel in the bottom before the post went in, then gravel judiciously tamped up beside the post within 2 inches or so of grade. Then I put in about two inches of Sakrete, sloped, high at the post and more or less at grade level at the outside perimeter. I can pretty much count on my neighborhood snow plow guy to snap the post at grade level before it gets frost heaved out of the ground.

For convenience outlets, sure. If you just want to hang some Christmas lights on the x-berry bushes at the far end of the back lawn, yes you can cut some corners. But if you want to run an underground cable to say a detached shop with its own 100 amp panel, don't screw around trying to save three dollars on dirt work. For hardwired items it is always cheaper to do it correctly the first time compared to doing it correctly the second time through.

[Bill Howatt]

Had linemen come to disconnect service while doing an upgrade. We are in very sandy soil - like the beach once below a few inches of topsoil. He said a problem they have with buried service lines are rocks, although rare here. The cable moves against the rock with the seasons and damages the insulation. No, the cables are buried nowhere near the frost depth. Because of the well-drained sand we don't have much trouble with frost heaves although people put foundation posts and the like down at least 4'.

[John Lifer]

Insure that you purchase a WATERPROOF GFCI if you put it outside in a box. There is a difference and I didn't in the past. Even a waterproof box will allow enough moisture to trip.

[Alan Lightstone]

Insure that you purchase a WATERPROOF GFCI if you put it outside in a box. There is a difference and I didn't in the past. Even a waterproof box will allow enough moisture to trip.
Or corrode. Earlier this summer I replaced an outdoor GFCI outlet that failed due to corrosion (nice mud dauber nest in there too).

Scott's advice regarding testing twice per year is IMHO a very good one. Not worried too much about the snow plows here, though. Never seen one.