# Underground feeders to sub



## Glock23gp (Mar 10, 2014)

WronGun said:


> Planning to run an underground feed in PVC from a main building 70’ across a driveway to another building 240V/100A.
> 
> A couple things crossed my mind
> 
> ...


3 wire URD or individual xhhw is what I use for cheaper short runs like that.

Seperate GEC is required there and yes you should bond everything accessible.

No 100a gfi required (not sure why would you think that?)

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## WronGun (Oct 18, 2013)

I wouldn’t use GFCI for a sub going next to a main, but because it’s underground in an 18” trench I was thinking maybe it could be required. 


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## telsa (May 22, 2015)

WronGun said:


> Planning to run an underground feed in PVC from a main building 70’ across a driveway to another building 240V/100A.
> 
> A couple things crossed my mind
> 
> ...


Sub panel is simply not a term of art used in Commercial work. 

Everything is simply a panel... 

Or perhaps a distribution board. ( something you'd find in an I-line catalogue. )

You make me think that this is to be a dinky 100A 1-phase scheme.

If it's derived off of a 208Y120 Service don't even think about down-sizing the neutral.

If 3-phase is ready to hand, this is the time to bring it across... IMHO.

Obviously, the prior work was inferior... foolish... risky... dumb actually.


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## WronGun (Oct 18, 2013)

Yes it’s a rinky dink single phase panel..

All the service wire I keep in stock I order same size N, it’s the way I’ve always done it. 


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## lighterup (Jun 14, 2013)

WronGun said:


> Planning to run an underground feed in PVC from a main building 70’ across a driveway to another building 240V/100A.
> 
> A couple things crossed my mind
> 
> ...


Are you actually meaning the main is 120/208? 
I would not pull just 2 legs off of a 3 phase main to feed a 
residential grade sub panel. I would tell your customer that
the use of that existing panel is wrong and they should keep
the whole system a true 3 phase. Just myu opinion.

Also , when you say "triplex" you don't mean the "messenger wire used
in overhead services right? Irregardless , 3 hots a neutral and a ground 
wire (THWN) is the way I would go.


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## WronGun (Oct 18, 2013)

It’s 120/240 


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## varmit (Apr 19, 2009)

You can buy underground aluminum quadraplex with 3 conductors the same size and with one conductor 2 sizes smaller. This stuff needs the conduit to be oversized a little or it does not pull well. If there are any rocks in the ground, direct burial is about a waste of time. 

For the job you describe, (2) #1, (2) #6 (1 N and 1 GND) XHHW aluminum in 1 1/2" PVC would be the way to go. you could pull a #1 N if you wished, but would not be required.

Yes, you will need a grounding electrode at the out building. Bonding is required of any systems that normally require bonding in area.


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## backstay (Feb 3, 2011)

You never said what the building's use was, or the load. You said 100 amp, did you mean 100 amp current or a 100 amp panel? It makes a difference. You also need two ground rods unless you can prove the resistance to ground.


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## sbrn33 (Mar 15, 2007)

I would run 2-2-2-4. if it is rocky soil I would sleeve it otherwise probably not for resi or ag. Whoever said to upsize your conduits was not kidding. 
Pretty rare is the need for 100 amps. I go with 60 almost everytime. 
Every once in awhile I will run the ground separate but really only when space is tight because then I can run #6. That wire is so cheap I never worry about cost much. 
In the old days we would run this on 3 wire every single time. Another one of the stupid codes out there.


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## WronGun (Oct 18, 2013)

I really don’t want to go below 18” on this either, in this case I think I need GFCI protection , I’ll have to look into this 


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## telsa (May 22, 2015)

You posted "driveway" -- the minimum cover must then be 24" above the top of your raceway.


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## WronGun (Oct 18, 2013)

telsa said:


> You posted "driveway" -- the minimum cover must then be 24" above the top of your raceway.




Ouch !

Ya , do they even have a 24” trencher? 




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## telsa (May 22, 2015)

Rent a Ditch-Witch chain trencher. They're as common as dust.

You'll want a trenching shovel, too.

A hefty wet-dry vacuum is lovely for pulling up the last of the loose spoils, BTW.

Have the ground surveyed for crossing utilities, too. 

I rather suspect that the old work was too shallow. So don't take comfort from where it was trenched.


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## WronGun (Oct 18, 2013)

I Already had ground inspected by digsafe.....I will rent a ditch witch , hopefully I don’t need to cut out a wide portion of pavement 


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## telsa (May 22, 2015)

WronGun said:


> I Already had ground inspected by digsafe.....I will rent a ditch witch , hopefully I don’t need to cut out a wide portion of pavement
> 
> 
> Sent from my iPhone using Tapatalk


Chain trenchers come in two basic sizes: walk-behind and ride on.

Even a walk-behind can get down pretty deep... but you're likely better off with a ride-on.

Don't expect the spoil to be suitable back-fill. 

Assume the worst.

I always use sand around my raceway -- meaning that my trench has to go all the way to 28-30" to provide bedding.

After the PVC has plenty of cover, you can back-fill with native materials -- as long as you remove rocks and stones. ( They'll screw up your compaction -- which, BTW -- is something that you'll really have to address seeings how you're crossing a driveway. You don't dare drive sharp stones down through your bedding of sand to injure your PVC.)

I'm so paranoid about getting perfect compaction -- under driveways -- that I stay with sand -- in damp lifts -- all the way up. This eliminates the need for a thumper and is very easy going.

I'd go with 1.5" or 2" PVC, BTW. ( if it fits your panels ) 

I also would go with aluminum XHHW... and my style is always a copper ground THWN. 

And so forth.


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## WronGun (Oct 18, 2013)

telsa said:


> Chain trenchers come in two basic sizes: walk-behind and ride on.
> 
> Even a walk-behind can get down pretty deep... but you're likely better off with a ride-on.
> 
> ...




Good point... the clients requested to take on backfil themselves, now I’m debating how to handle this...I didn’t put that much thought into backfill but now I can see this is very critical in this application 


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## telsa (May 22, 2015)

Yes, it IS.

It's virtually guaranteed that they'll screw this up.

They'll go cheap... like how they handled the work you're fixing// replacing.


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## WronGun (Oct 18, 2013)

telsa said:


> Yes, it IS.
> 
> It's virtually guaranteed that they'll screw this up.
> 
> They'll go cheap... like how they handled the work you're fixing// replacing.




Ya it’s underground direct burial service conductors and they are not deep by any means 


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## telsa (May 22, 2015)

The more I read, the more I think that they, themselves, performed the original work.

That would explain just about everything.


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## catsparky1 (Sep 24, 2013)

120-240 stinger ?


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## WronGun (Oct 18, 2013)

When is schedule 80 required ? It sure if this should be in 40 or 80

This is underground so it’s not an area that will be exposed to physical damage , I️ believe I️ just answered my own question! Damn I’m good 

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## WronGun (Oct 18, 2013)

Looking for some help here... we are just about done with this trench and started piping and we are at 420 degrees between building in a parking lot. 

We can handhole in a flowerbed but it still requires a 90 to get into the hand hole so it doesn’t solve the issue.... any suggestions?

We are using aluminum feeders is it necessary to 90 up into a hand hole?


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## WronGun (Oct 18, 2013)

I’m running 1/0 AL in PVC sched 40 , some areas Sched 80.

The building already has a 100A panel we are refeeding it because the EC before just buried cables and they did not last

My problem is staying under 360 in a parking lot 
Is it necessary to 90 up Into the handhole

If I can run straight into the hand hole I avoid the last 90 I can play with elevation so the pipe isn’t laying low but at a higher entry into the handhole 













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## WronGun (Oct 18, 2013)

Any help with this would be appreciated.... 


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## WronGun (Oct 18, 2013)

Picture diagram

Possible Hand-hole at flower bed however I believe I still need to 90 up into the hand-hole so I don’t see how this can help 











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## trentonmakes (Mar 21, 2017)

Put it between 45 and 22 deg bends

Texting and Driving


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## WronGun (Oct 18, 2013)

trentonmakes said:


> Put it between 45 and 22 deg bends
> 
> Texting and Driving




I was hoping to stay out of the drive way , but I don’t think that’s an option we will need a heavy duty handhole 


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## trentonmakes (Mar 21, 2017)

Put it after the 2nd 90?

Theres a couple options there. Wherever you put it, it resets your 360

Texting and Driving


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## Dark Knight (Jan 6, 2016)

Don't you guys have ACWU down there?


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## trentonmakes (Mar 21, 2017)

WronGun said:


> Picture diagram
> 
> Possible Hand-hole at flower bed however I believe I still need to 90 up into the hand-hole so I don’t see how this can help
> 
> ...


Place it right at the stub up of main or sub building and looks like you'll be fine
???

Texting and Driving


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## WronGun (Oct 18, 2013)

trentonmakes said:


> Place it right at the stub up of main or sub building and looks like you'll be fine
> ???
> 
> Texting and Driving




that stub up still requires the very last 90
So I’ll still be at 427 degrees.

Here at the pink X is an option. It’s not a traffic area but still considered a driveway.. 

I’m assuming there is a traffic rated hand-hole?












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## trentonmakes (Mar 21, 2017)

WronGun said:


> that stub up still requires the very last 90
> So I’ll still be at 427 degrees.
> 
> Here at the pink X is an option. It’s not a traffic area but still considered a driveway..
> ...


90+90+45+22=......
247!
Ooops
90+90+90+45+22=347
Still good

Plop in hand hole your good for another 360! So that last stub up is non issue.
You can put it close to building so its not in driveway and relatively away from anything else.

Texting and Driving


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## active1 (Dec 29, 2009)

Do you really need the back to back 90s on each end?
Can you kick the 90s so you only need a 45 on the top and possibly straight into the 90 up on the bottom?

Don't know if you already trenched it but I would have tried to leave the 22 out and put a a slight curve in the run. It's not like it adds up to be a symmetrical run now.
45+22=67 degrees or 23 short of a 90 right. 
With dirt it's about no bends, curves don't count much. Not exact degrees.


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## WronGun (Oct 18, 2013)

trentonmakes said:


> 90+90+45+22=......
> 247!
> 
> Plop in hand hole your good for another 360! So that last stub up is non issue.
> ...




Maybe I’m missing something here but don’t I need to 90 up into the hand-hole? Or are you saying just run straight into the hand-hole










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## trentonmakes (Mar 21, 2017)

active1 said:


> Do you really need the back to back 90s on each end?
> Can you kick the 90s so you only need a 45 on the top and possibly straight into the 90 up on the bottom?
> 
> Don't know if you already trenched it but I would have tried to leave the 22 out and put a a slight curve in the run. It's not like it adds up to be a symmetrical run now.
> ...


Was wondering that too!
Why not just make B line to where ya need to go

Texting and Driving


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## WronGun (Oct 18, 2013)

To be honest it’s a very slight tweak probably not even 22. But I’m being safe and calling it 22.... I’m still to far over.

We had a different/easier route until we ran into a very large concrete pour 12” below asphalt in 1 area..

So the asphalt is cut and trench is done and this is what I have to work with. 


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## trentonmakes (Mar 21, 2017)

WronGun said:


> Maybe I’m missing something here but don’t I need to 90 up into the hand-hole? Or are you saying just run straight into the hand-hole
> 
> 
> 
> ...


X marks the spot!
Or 2 handholes









Texting and Driving


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## active1 (Dec 29, 2009)

I know you did some trenching already.
Keeping your run with the 45 in the middle.
Guessing about a 30 bend on the top.
And either cheating the bottom or a 10 to 15 degree.
Total would be 255 to 270 degrees.


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## WronGun (Oct 18, 2013)

I see what your saying....I know it seems odd to run the way I did. For the sake of the drawing I just wanted to get the point across of my pipe run. 

But the sub building is slightly in a different position than what’s on paper.. If I ran straight in I would be going into the glass slider when I actually needed to make the bends to creep around the corner to the wall perpendicular to the glass slider 











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## WronGun (Oct 18, 2013)

Just realized I drew it wrong 

It’s actually positioned like this 

Same bends 

Just understand we didn’t go straight Into the buildings because of restrictions... The obvious route was not taken for different reasons. I just didn’t feel I needed to post this.

There are a number of obvious better ways of running the pipe and my post doesn’t give all the reasons why we did what we did. It was just about solving the current pipe run and keeping it under degree, Telsa

In regards to the drawing I could draw a straight line right into each building with hardly any bend. 

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## trentonmakes (Mar 21, 2017)

Id go with 2 handholes, 1 right before ea stub up to building


Texting and Driving


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## active1 (Dec 29, 2009)

Some people when they run conduit in a building they don't put much thought in the run. Just placing conduit, having to constantly adjust elevation an jog around obstetrical until done. When they realize they forgot to count the bends, need to add pull boxes, and there may have been a better route that would have saved a lot.

Don't see that happen much with trenching.


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## telsa (May 22, 2015)

I see two (2) 90s that could've been 45s.

Problem -- GONE.


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## WronGun (Oct 18, 2013)

Problem solved 

The last 90 is actually after the handhole which I’m sure qualifies as a degree reset










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## sbrn33 (Mar 15, 2007)

degrees of bend is really just a recommendation. nobody give a **** in real life.


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## RePhase277 (Feb 5, 2008)

sbrn33 said:


> degrees of bend is really just a recommendation. nobody give a **** in real life.


Says the guy sitting in the truck, posting on ET.


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## Majewski (Jan 8, 2016)

Maybe a well written piece of wording in the contract(s) can spell out responsibility, warranty and what not with them taking on backfill?


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## Majewski (Jan 8, 2016)

Jesus I made a reply from page one not realizing 2 other pages exist.... anywho...


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## WronGun (Oct 18, 2013)

Anyways ......... inspection passed 


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## trentonmakes (Mar 21, 2017)

WronGun said:


> Problem solved
> 
> The last 90 is actually after the handhole which I’m sure qualifies as a degree reset
> 
> ...


You need a heatbox!

Texting and Driving


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## WronGun (Oct 18, 2013)

trentonmakes said:


> You need a heatbox!
> 
> Texting and Driving




I have a heat box


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## lighterup (Jun 14, 2013)

trentonmakes said:


> You need a heatbox!
> 
> Texting and Driving


Heat Box! Ahhh..there you go again!...Darknight! Over here<


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## sbrn33 (Mar 15, 2007)

RePhase277 said:


> Says the guy sitting in the truck, posting on ET.


Actually was at the Olympic trials for curling.


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## trentonmakes (Mar 21, 2017)

lighterup said:


> Heat Box! Ahhh..there you go again!...Darknight! Over here<


[emoji13]

I didnt see expansion joints at 1st glance, just the sweeps.

Texting and Driving


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## lighterup (Jun 14, 2013)

trentonmakes said:


> [emoji13]
> 
> I didnt see expansion joints at 1st glance, just the sweeps.
> 
> Texting and Driving


I know the box contained heat , but was this a larger (ish) sized box
or on the smaller side?


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## RePhase277 (Feb 5, 2008)

sbrn33 said:


> Actually was at the Olympic trials for curling.


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