Need outside electrical consult

[miketyler]

Am moving forward with our iron fence project. Phase one is eight decorative columns that will be placed in the corners and midpoints on the acre lot. Stealing some design cues from another house in our neighborhood we have installed glass block on each of the four sides of these decorative 6ft columns and want to illuminate them with 40 watt or equivalent CFL bulbs.

The total run of iron fence will be around 600ft and thus the electrical run will be about that give or take 20-30ft. We placed 3/4" PVC pipe in the footings before they were poured that allows a short 2ft raceway with which the UF-B cable can be pulled.

Once utilities come out and flag existing lines we intend to start running cable. I found the NEC on direct burial cable here and want to make sure I undersand this correctly:

http://www.irrigation.org/uploadedFiles/Certification/National%20Electric%20Code.pdf

It looks like this cable must be buried 12" deep if branch circuit with GFCI and under 20 amps. The 12-2 UF-B cable will come up above ground and tie in to service panel in deatached garage. With 12-2 am hoping voltage drop would be within tolerance.

Any thoughts here? While I am not a licensed electrician I know basic best practices and have run new circuits and added brekaers to service panels but this is a much larger project and am hoping to get some professional feedback.

[STANGGT40]

Am moving forward with our iron fence project. Phase one is eight decorative columns that will be placed in the corners and midpoints on the acre lot. Stealing some design cues from another house in our neighborhood we have installed glass block on each of the four sides of these decorative 6ft columns and want to illuminate them with 40 watt or equivalent CFL bulbs.

The total run of iron fence will be around 600ft and thus the electrical run will be about that give or take 20-30ft. We placed 3/4" PVC pipe in the footings before they were poured that allows a short 2ft raceway with which the UF-B cable can be pulled.

Once utilities come out and flag existing lines we intend to start running cable. I found the NEC on direct burial cable here and want to make sure I undersand this correctly:

http://www.irrigation.org/uploadedFiles/Certification/National%20Electric%20Code.pdf

It looks like this cable must be buried 12" deep if branch circuit with GFCI and under 20 amps. The 12-2 UF-B cable will come up above ground and tie in to service panel in deatached garage. With 12-2 am hoping voltage drop would be within tolerance.

Any thoughts here? While I am not a licensed electrician I know basic best practices and have run new circuits and added brekaers to service panels but this is a much larger project and am hoping to get some professional feedback.

i would use a #10 copper wire (you want to keep voltage drop under 3% on branch ckts...at 2-amps, #10 would be around 2% at 600' - 120v)... and run pvc conduit it's cheap, and you can easily pull more wires in, later, if you decide to do something else. i'm not a fan of direct burial. you could rn a 3/4" pvc, but the difference in price is very minimal, so i would run a 1" or maybe even a 1 1/2" pvc conduit...it would make it really easy to pull through.

[Vertnut]

Am moving forward with our iron fence project. Phase one is eight decorative columns that will be placed in the corners and midpoints on the acre lot. Stealing some design cues from another house in our neighborhood we have installed glass block on each of the four sides of these decorative 6ft columns and want to illuminate them with 40 watt or equivalent CFL bulbs.

The total run of iron fence will be around 600ft and thus the electrical run will be about that give or take 20-30ft. We placed 3/4" PVC pipe in the footings before they were poured that allows a short 2ft raceway with which the UF-B cable can be pulled.

Once utilities come out and flag existing lines we intend to start running cable. I found the NEC on direct burial cable here and want to make sure I undersand this correctly:

http://www.irrigation.org/uploadedFiles/Certification/National%20Electric%20Code.pdf

It looks like this cable must be buried 12" deep if branch circuit with GFCI and under 20 amps. The 12-2 UF-B cable will come up above ground and tie in to service panel in deatached garage. With 12-2 am hoping voltage drop would be within tolerance.

Any thoughts here? While I am not a licensed electrician I know basic best practices and have run new circuits and added brekaers to service panels but this is a much larger project and am hoping to get some professional feedback.

I guess the footings and columns turned out OK?

[miketyler]

How much voltage drop would I be looking at with the 12-2? If I went with three separate copper conductors and shrouded in PVC, does that reduce the minimum depth to be within code? With the 3/4" PVC I have already installed in the footings for entry and exit, I am not sure how much larger I can go. I would however like the flexibility to move up to larger bulbs if I wanted to in the future. What type cable are you suggesting would work?

Hey Randy - sorry for not getting back. The project picked up momentum quickly.Yes, I think we are ok. My guys level lined the tops of the columns on the two long sides of the property which are most visible. As a result, some columns are slightly taller than others. I would have liked those variations to have been incorporated in the footings. They did accomplish this to a degree but I have one low spot that is over a foot low and I will have to come in with several yards of dirt and try and grade that in. That column is over 7ft tall right now. Hopefully will all work out once we bring in dirt to grade off around it.

[STANGGT40]

How much voltage drop would I be looking at with the 12-2? If I went with three separate copper conductors and shrouded in PVC, does that reduce the minimum depth to be within code? With the 3/4" PVC I have already installed in the footings for entry and exit, I am not sure how much larger I can go. I would however like the flexibility to move up to larger bulbs if I wanted to in the future. What type cable are you suggesting would work?

Hey Randy - sorry for not getting back. The project piced up momentum quickly.Yes, I think we are ok. My guys level lined the tops of the columns on the two long sides of the property which are most visible. As a result, some columns are slightly taller than others. I would have liked those variations to have been incorporated in the footings. They did accomplish this to a degree but I have one low spot that is over a foot low and I will have to come in with several yards of dirt and try and grade that in. That column is over 7ft tall right now. Hopefully will all work out once we bring in dirt to grade off around it.

bury it 18"...that's a decently safe depth, anyway, so you are less likely to hit it. you would be ok with #12, but #10 would give you a tad more flexibility. stay under 2 amps, at the end (which is very easy with fluorescent lamps), and you'll be in good shape. a standard 13 watt (equivalent light output to a 60watt incandescent) would be about .11 amp each. you're not going to want to put in a receptacle and use a drill, at the end of the run, but you'll be ok with the lights.

[miketyler]

So the 12-2 UF-B would be good to go at 18" direct burial?

[crooner]

Man I would run PVC and use THHN wire. I haven't priced UF cable in awhile but I bet it's still pretty high.

Like stang40 I'm also an electrician and I never use direct burial cable. We always run PVC.

[miketyler]

With THHN/THWN in PVC is 18" depth still required depth?

[STANGGT40]

So the 12-2 UF-B would be good to go at 18" direct burial?

Man I would run PVC and use THHN wire. I haven't priced UF cable in awhile but I bet it's still pretty high.

Like stang40 I'm also an electrician and I never use direct burial cable. We always run PVC.

it would be fine, but i would run the pvc and pull thhn wire through it. that's up to you, though. if you're going to run pvc, definitely don't pull the uf through it...it would be much cheaper to just get the thhn wire, on spools, and pull it through.

[STANGGT40]

With THHN/THWN in PVC is 18" depth still required depth?

yes...if you get some time to search, just look up table 300.5 (nec) for minimum cover requirements. i would go as deep as you can, within reason.

[miketyler]

The PVC is only ab out 36" long and provides a short raceway in and out of each column. Otherwise I was planning on going direct burial for the long lengths.

[crooner]

Also, with PVC you don't have to have a GFI at the panel.

[zora04]

i would use a #10 copper wire (you want to keep voltage drop under 3% on branch ckts...at 2-amps, #10 would be around 2% at 600' - 120v)... and run pvc conduit it's cheap, and you can easily pull more wires in, later, if you decide to do something else. i'm not a fan of direct burial. you could rn a 3/4" pvc, but the difference in price is very minimal, so i would run a 1" or maybe even a 1 1/2" pvc conduit...it would make it really easy to pull through.

definitely run PVC with THHN. Direct bury is not a good option ever IMO. Have you already purchased the lights? They make an assortment of LED lights now, which will reduce your load and last forever. I have similar plans at my place, and will be going with LED's. The upfront cost is more expensive, but in my opinion worth it.

[miketyler]

I haven't bought lights yet but have got 750ft of 12-2 UF-B cabling. I plan to trench it soon as soon as all the utilities come out and flag their locations. I decided to run the source from the detached garage and create two runs, one long and one short that will tee into the garage panel. This saves me from going under the driveway to the main panel.

Would there be any real benefit to run #10UF-B out to the first column, then join the #12 lines form there?