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Old 05-10-2011, 08:00 AM   #1
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NEC and burial of service line


I have several threads started with various questions about a small shop I am going to have wired. I posted this question in one of those threads but did not get a response.

I am going to have to bury my service line in conduit 18" deep. I'm still waiting on an electrician to come and look a it. I figure the least I can do is start digging the ditch. It runs from the shop to the panel on the side of the house, over a distance of about 75'.

Is there anything in the code that dictates how close it can be to a structure? The planned path goes up beside the house about 2' away from it until it reaches the panel. Is this accpetable?

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Old 05-10-2011, 08:13 AM   #2
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NEC and burial of service line


No requirement how close/far from a structure. Just common sense. You're good.

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Old 05-10-2011, 08:17 AM   #3
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No requirement how close/far from a structure. Just common sense. You're good.
Sounds good. I just didn't want to start digging it and have to redo it
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Old 05-10-2011, 08:31 AM   #4
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NEC and burial of service line


FWIW...Just a correction of terminology...you mentioned "bury my service line"...it would be a feeder if it's hooked to a breaker (over-current protected) in one panel and leaves to feed another panel which in turn has breakers/fuses to protect branch circuits that come from that panel. I mention it because service conductors can have different rules for some things that feeders don't.

Have fun digging!!
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Old 05-10-2011, 09:23 AM   #5
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FWIW...Just a correction of terminology...you mentioned "bury my service line"...it would be a feeder if it's hooked to a breaker (over-current protected) in one panel and leaves to feed another panel which in turn has breakers/fuses to protect branch circuits that come from that panel. I mention it because service conductors can have different rules for some things that feeders don't.

Have fun digging!!
Ok, you are correct. It would be a feeder. It will run from my main panel on my house to a sub panel in the shop.
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Old 05-10-2011, 11:17 AM   #6
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NEC and burial of service line


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Ok, you are correct. It would be a feeder. It will run from my main panel on my house to a sub panel in the shop.

And do not forget you need four wires. H-H-N-G.
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Old 05-10-2011, 11:28 AM   #7
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And do not forget you need four wires. H-H-N-G.
Yes, I was planning on running 2224 aluminum so I can get 90 amps.
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Old 05-26-2011, 10:56 AM   #8
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NEC and burial of service line


Just one more favor to ask..

Can somebody show me the specific paragraph in the code that states feeders must be 18" deep if in conduit?

A local electrical inspector told me that feeders need to be 18" deep if in conduit and 24" deep if direct burial. I just want to see the passage in the NEC that states that.
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Old 05-26-2011, 11:25 AM   #9
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NEC and burial of service line


Since I just went through this, it depends if it is metal or pvc conduit. Reference table 300.5

I ended my run on both ends as close to the building as possible, I used 21" simply because I wanted to enter the building as low as possible, so I used a long turn elbow to go up directly into an LB fitting. As I was in rigid metal conduit, I was only required to be 6" deep.

I passed the trench inspection yesterday, after which it rained a lot so I took the attached photo of my trench where my garage feeder leaves the house.
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NEC and burial of service line-trench-house-after-lot-rain.jpg  
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Old 05-26-2011, 11:33 AM   #10
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NEC and burial of service line


Correct...Table 300.5
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Old 05-26-2011, 11:34 AM   #11
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Since I just went through this, it depends if it is metal or pvc conduit. Reference table 300.5

I ended my run on both ends as close to the building as possible, I used 21" simply because I wanted to enter the building as low as possible, so I used a long turn elbow to go up directly into an LB fitting. As I was in rigid metal conduit, I was only required to be 6" deep.

I passed the trench inspection yesterday, after which it rained a lot so I took the attached photo of my trench where my garage feeder leaves the house.
From that table I am assuming I am looking at column 3. Is this correct? I will be running 2,2,2,4 Al feeder between my main panel on my house to a sub panel in the outbuilding. It will be placed in the gray PVC pipe - the stuff for underground electrical/electrical in general.

The ditch between these two panels does not go under any road, driveway, building, or parking areas. Simply though the backyard, and along the side of the house until it gets to the panel.
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Old 05-26-2011, 11:42 AM   #12
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Yep...column 3....18"
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Old 05-26-2011, 11:52 AM   #13
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NEC and burial of service line


Schedule 80 for risers if your inspector will consider that an area subject to physical damage. Schedule 40 is not rated for physical damage.

What type cable are you using? Just want to check to make sure it's not SE-R. Not allowed underground whether it is in a raceway or not. You need USE or conductors rated for wet location.
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Old 05-26-2011, 11:59 AM   #14
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NEC and burial of service line


that is 18" of cover on top of the pipe that is in the ditch. what I am saying is the trench will need to be over 18" deep. happy digging! I wish I had customers like you that would do the digging.
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Old 05-26-2011, 12:04 PM   #15
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Ok, I'm pretty sure the yellow box I have here outlined down on the left side doesn't apply to me. I just highlighted because I wasn't sure and need clarification of if it does apply.

If that does not apply to me, I assume it puts me in the top red box catagory I have highlighted. Judging from the columns I think I have a choice here. If I go with metal conduit (colum 2) it only has to be 6", If I go with the plastic stuff (column 3) it has to be 18". Did I interpret that correctly? If so, why in the world does it have to be so much deeper if in plastic pipe as opposed to metal?

I'm pretty sure my local code is based on this but they may have their own codes on top of it. I just want to be sure I understand the code before i call and question them.

Here is the table from the 2008 NEC I have..Don't know if it changed in the 2011 edition


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