block fence/electrical wiring question

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Old 06-07-11, 12:19 PM
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block fence/electrical wiring question

I'm in the process of installing a block fence and would also like to install the wiring infrastructure to service electrical outlets throughout. Are there any requirements or does someone know what kind of conduit material I need? PVC pipes? and how far from the ground should the receptacles be installed? And how will they be grounded? 120'x6' fence.
 
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Old 06-07-11, 12:37 PM
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Originally Posted by miszxj View Post
I'm in the process of installing a block fence and would also like to install the wiring infrastructure to service electrical outlets throughout.
Do you want the receptacles recessed into the block wall or mounted to the surface of it? I would recommend surface mount. The boxes should be "bell boxes" with threaded hubs for outdoor use. There is also a plastic version with glue-in hubs for PVC conduit.

Are there any requirements or does someone know what kind of conduit material I need? PVC pipes?
PVC electrical conduit (grey) or EMT thinwall metal conduit are acceptable. It is best to paint the EMT when used outside to prevent rusting.

and how far from the ground should the receptacles be installed?
No less than 12" above the snow line if applicable.

And how will they be grounded?
A #12 green or bare copper wire pulled through the conduit with the black hot and white neutral.
 
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Old 06-07-11, 01:58 PM
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Thank you I will go with the "bell boxes".

Can the conduit be within the block wall? So that it will not be visible?
 
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Old 06-07-11, 02:50 PM
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Is this concrete blocks or solid landscaping blocks?
 
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Old 06-07-11, 03:19 PM
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concrete (cinder blocks) they have two hollow comparments.
 
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Old 06-07-11, 03:28 PM
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If you leave the block voids hollow (do not fill with sand, gravel, mortar) you can run the EMT through them. If you intend to fill the voids, use rigid PVC conduit or ENT (electric non-metal tubing) which is a flexible PVC conduit usually bright blue in color.

The reason for the difference is that the metal EMT will rust out quickly if embedded in masonry.
 
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Old 06-07-11, 03:47 PM
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Thank you I will use the rigid PVC conduit (ENT). I think this will be my final question.

I will be drawing the electricity from the house which is 4 feet from the fence. My approach is to go under ground.

How deep should I dig the trench? and can I use the same PVC conduit?
 
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Old 06-07-11, 04:01 PM
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12" if the GFCI protection is before the trench, 18" if after. Rigid PVC is okay underground.
 
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Old 06-07-11, 04:22 PM
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Thank you for your help. for 125' it is obvious I need to get 125 feet of pipe and wires. Is this correct? I'm also thinking of mounting 4-5 receptacles how much more feet of pipes and wires you think I should purchase?
 
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Old 06-07-11, 04:44 PM
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got it, thank you again for your help. doing this project over this weekend. I'll keep you posted.
 
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Old 06-07-11, 05:02 PM
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"ENT is flexible tubing sometimes called Smurf because it is blue"

can this be threaded through the block wall!?
 
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Old 06-07-11, 05:02 PM
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Originally Posted by miszxj View Post
Thank you for your help. for 125' it is obvious I need to get 125 feet of pipe and wires. Is this correct? I'm also thinking of mounting 4-5 receptacles how much more feet of pipes and wires you think I should purchase?
You need to first determine the total length of conduit you will be using. For example, if you are going down and up between the receptacles you will need to take that into consideration in determining the total length of conduit. Say your receptacles are ten feet apart and four feet above grade. You might be dropping down four feet, running ten feet and coming back up four feet between two receptacles for a total of 18 feet of conduit and wire. You also need a minimum of six inches of wire in each receptacle box for each "run" of wire so for all but the last receptacle you need to figure a minimum of one additional foot of wire over the length of conduit.

I don't know how you are planning on running the conduit but remember that a standard concrete (cinder) block is only eight inches wide on the outside dimension with the internal "cell" considerably less. You might have trouble fitting 90 degree bends in a horizontal plane and you might end up with both "up/down" and horizontal conduit runs. If what I envision is correct (a wall of concrete block with no visible conduit, just receptacles) you are going to need a lot more than 125 feet of conduit and consequently a lot more than 125 feet of wire. Don't forget the length of conduit (and wire) in the run between the wall and the source of power.
 
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Old 06-07-11, 06:19 PM
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Originally Posted by miszxj View Post
Thank you I will go with the "bell boxes".

Can the conduit be within the block wall? So that it will not be visible?
"Bell Boxes" are for surface installation and you want the conduit to be concealed within the block wall, is that correct? If so, I am thinking you should use masonry boxes that will provide a flush receptacle and forget the surface mounted boxes. But, an installation like that is far more complicated than an inexperienced DIYer can usually handle. Considering that this is obviously a first time attempt at a project like this, I think you would be way ahead to use the surface "Bell Boxes" and surface mounted conduits.
 
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Old 06-07-11, 06:26 PM
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ok, i'll check it out at the hardware store. thanks again for your help.
 
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Old 06-08-11, 01:58 PM
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Ray, I do not think those boxes are approved for wet/damp locations.
 
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Old 06-08-11, 02:28 PM
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mixcsj -

Since you are in SoCal, if you you to Orco Block, you may find some units like/similar to what the previous poster sketched - no guarantee, but I swear I saw some similar in the yard at one of the plants (not a stock item) a few years ago. they make a far better selection of units than in most eastern markets.

If you go to your local code office, you may be able to get the design standards for the wall construction since concrete masonry privacy walls have been common for decades and the standards are well established and done for free.

Dick
 
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Old 06-08-11, 03:27 PM
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Originally Posted by Justin Smith View Post
Ray, I do not think those boxes are approved for wet/damp locations.
I suspect you are correct. I should have looked more carefully.
 
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Old 06-08-11, 06:07 PM
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On further checking some of my original suggestions just wouldn't have been code compliant and I have deleted them. My final suggestion is as other have suggested surface mount and I'll add my suggestion to run Carflex flex seal tight conduit through notches in the ends of one row of blocks. Come down into the cell and into the back of a bell box through a hole in the block and then back out and on to the next.
 
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