DIY Home Improvement Forum banner
1 - 20 of 23 Posts

·
Lost..
Joined
·
344 Posts
Discussion Starter · #1 ·
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?
 

·
Master Electrician
Joined
·
1,453 Posts
No requirement how close/far from a structure. Just common sense. You're good.
 

·
Master Electrician
Joined
·
1,453 Posts
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!! :thumbsup:
 

·
Lost..
Joined
·
344 Posts
Discussion Starter · #5 ·
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!! :thumbsup:
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.
 

·
Lost..
Joined
·
344 Posts
Discussion Starter · #8 ·
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.
 

·
Registered
Joined
·
1,504 Posts
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.
 

Attachments

·
Lost..
Joined
·
344 Posts
Discussion Starter · #11 ·
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.
 

·
Registered
Joined
·
1,504 Posts
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.
 

·
Electromagician
Joined
·
79 Posts
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.
 

·
Lost..
Joined
·
344 Posts
Discussion Starter · #15 ·
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

 

·
Registered
Joined
·
1,504 Posts
75' is a long way, they have walk-behind trench digging machines you can rent. It took 2 teenagers around 10 hours to dig my 32' trench. There were a lot of roots to cut through, but it was still cheaper than the rental. $120 minimum rental charge for 4 hours where I live, but you'd have the trench dug in 30 minutes. I did this when I was running a trench for gas and electric for a pool and heater at a previous house.
 

·
Lost..
Joined
·
344 Posts
Discussion Starter · #17 ·
75' is a long way, they have walk-behind trench digging machines you can rent. It took 2 teenagers around 10 hours to dig my 32' trench. There were a lot of roots to cut through, but it was still cheaper than the rental. $120 minimum rental charge for 4 hours where I live, but you'd have the trench dug in 30 minutes. I did this when I was running a trench for gas and electric for a pool and heater at a previous house.
I know it is a long way. I already have it done 18" about halfway. I'm just double checking the code and trying to be sure that it doesn't have to be deeper. I wish it did have to be 6" all the way, I would have been done by now. I'm trying to cut some of the labor costs from the electrician. I've already established that I cannot do the work myself from my local building dept, at least as far as wiring goes, and I am just trying to do what I can.

I could have rented a trencher, but like you say it costs..Shovels and a pick axe are a pain in the back but they are free :lol:
 

·
Registered
Joined
·
1,504 Posts
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.
You had said that this isn't under a driveway or an area you're parking cars so this doesn't 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?
Rigid metal conduit has pretty heavy wall, it's not going to be damaged by anything like a shovel. At 6" of cover, a shovel will hit it. The plastic would likely crack.

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
2008 is more likely in effect than 2011, you should check, but many areas are 3 years behind. For Michigan, 2008 only went into effect at the beginning of April of this year.
 

·
Lost..
Joined
·
344 Posts
Discussion Starter · #19 ·
Rigid metal conduit has pretty heavy wall, it's not going to be damaged by anything like a shovel. At 6" of cover, a shovel will hit it. The plastic would likely crack.
Makes sense. Thanks

Is it more expensive to run metal as opposed to plastic? I think I may not be able to do metal anyway because my pipe going into the footing and coming up into the shop is plastic. I would think it would have to be 100% metal to abide by code in order to dig the ditch at 6" deep.

2008 is more likely in effect than 2011, you should check, but many areas are 3 years behind. For Michigan, 2008 only went into effect at the beginning of April of this year.
As far as I know we are still using the 2008 code in my city.
 

·
Registered
Joined
·
1,504 Posts
Makes sense. Thanks

Is it more expensive to run metal as opposed to plastic? I think I may not be able to do metal anyway because my pipe going into the footing and coming up into the shop is plastic. I would think it would have to be 100% metal to abide by code in order to dig the ditch at 6" deep.



As far as I know we are still using the 2008 code in my city.
I don't know what schedule 80 PVC conduit costs because I gave up trying to find it, but schedule 40 conduit for a 10' long piece in 2" diameter is $4.79. In rigid metal conduit, a 2" diameter pipe 10' long is $48 and change.

That would be a yes. More expensive.
 
1 - 20 of 23 Posts
Top