# Underground service entrance cable requirements.



## kgt55 (Jun 12, 2009)

I'd be very grateful to those who could advise me in the proper selection of cable, conduit, and other materials to pass inspection for the following situation.

I have replaced a 100 amp fuse box located on an interior wall with a 200 amp circuit breaker panel. It's location is at ground level and is located on an interior wall 18" perpendicular from an outside wall, and has a crawlspace/storage area behind it.

My goal is to have the existing 100 amp overhead service removed after installing 200 amp underground service cable and entrance conduit. I am also building a garage/studio next year and want to install 200 amp underground service to that structure, fed from the home.

The power company will have the meter installed on the power pole located 220' (terminal to terminal) from the home. The future garage/studio breaker box will be located approx. 50' (termimal to terminal) from the home breaker box.

1) What total amperage service is required to serve both buildings from one meter location on the pole?

2) What size and type of underground cable would be required?
The power company requires two hots, a neutral, and a ground wire.
Would a quadruplex cable be ok for this application even though it's meant for 3 phase usage, (not a green or bare grounding cable, but insulated and black in color)?

3) Being that the home breaker box is not on an outside wall (18" away), I'd like to run schedule 80 pipe underground into the home inside the crawspace/storage area, then up the wall into the back of the breaker box. I do not want any boxes, pipe, or LB's located on the outside of the buildings if possible. Distance inside the home would be 5' or less for the underground cable up to termination.

4) I was considering the use of 350 kcmil x 4 aluminum quadruplex urd/use cable by Southwire (or larger) and schedule 80 of what size?

5) Will the urd/use cable be ok inside the schedule 80 for this short distance inside the home and garage?

I am located in a rural area outside the city limits of Duluth Minnesota and am allowed to do my own service entrance work up to the terminals of the meter box on the power pole.

Thanks in advance for your help.
Keith


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## dSilanskas (Mar 23, 2008)

1) What total amperage service is required to serve both buildings from one meter location on the pole? *If you are installing a 200 amp service to your house that should be plenty of power for your garage as well. Remember its not about how many amps the service is its about what your draw is :wink:. So what I would do would be install the 200 amp panel in your house like you said. Than install a 100 amp 32 circuit panel in your garage. That gives plenty of room for whatever circuits you want installed.*

2) What size and type of underground cable would be required?
The power company requires two hots, a neutral, and a ground wire.
Would a quadruplex cable be ok for this application even though it's meant for 3 phase usage, (not a green or bare grounding cable, but insulated and black in color)? *From the pole to your house you can run a 4/0 Quadruplex. Just make sure the wires are indeed identified on both ends.*

3) Being that the home breaker box is not on an outside wall (18" away), I'd like to run schedule 80 pipe underground into the home inside the crawspace/storage area, then up the wall into the back of the breaker box. I do not want any boxes, pipe, or LB's located on the outside of the buildings if possible. Distance inside the home would be 5' or less for the underground cable up to termination. *That is fine but you only need to use schedule 40 unless the pipe run is under a driveway.*

4) I was considering the use of 350 kcmil x 4 aluminum quadruplex urd/use cable by Southwire (or larger) and schedule 80 of what size? *350 kcmil :no: That is a bit over kill and you don't need to use that size of a wire. If your run from the pole to your house is under 500' 4/0 is fine for 200 amps. And from your house to your garage if you install the 100 amp panel like I suggested you can use 4/2 quadruplex. The size of the pipe from the pole to your house should be 2" and if you go with the 100 amp panel in your garage use 1 1/4" PVC*

5) Will the urd/use cable be ok inside the schedule 80 for this short distance inside the home and garage? *Quadruplex can be installed in pipe yes its fine. Good luck and be safe!*


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## 300zx (May 24, 2009)

+1 :thumbsup:


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## nap (Dec 4, 2007)

so, do you need the 200 amp in the outbuilding? If so, I would go about this a very different way.

I would put a 320 amp meter on the pole and run seperate feeders to each building.

If you need 200 amp in the outbuilding and want to run through the house, you will need to install a 400 amp panel in the house and then run a 200 amp feed to the outbuilding. This can be run from a 320 service/meter.



Personally, I would run seperate feeders to each building regardless. That way you do not involve the house power with the outbuilding power.



as to sched 40 or 80 PVC. Code requires any place the conduit is subject to physical damage, it needs to be 80. Under a driveway can be 40 the last time I looked in the good book. I saw no place in your description that 80 would be required with the exception of the riser out of the ground at the pole to the meter.


if you run from the house to the outbuilding, chances are you will need 4 conductors (at least 3 insulated). 08 code and previous code if there are any other electrical pathways between the two buildings (phoneline, cable, metal clothesline tied to each building, etc.) require the 4 conductors be used. You will also need to install a grounding electrode system at the outbuilding as well.


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## kgt55 (Jun 12, 2009)

*How much capacity is left?*

Thanks gentlemen for your wisdom and knowlege!

Of course I am after the best bang for the buck, still considering a saftey factor.

1) The outbuildings load requirements will be for an office/studio on 2nd floor, and workshop/garaging on the 1st floor, ( a 3+, 2 story building). The loads are to include central air and forced air L.P. HVAC.

2) Part of the run from the power pole to the home will be under a driveway, (gravel for a year or two at first).

3) HOW DO I GO ABOUT DETERMINING (or know) THE MAXIMUM SIZE SERVICE PANEL the outbuilding could have when we know the home has a 200 amp panel, a 220' run from the power pole, the outbuilding panel is a maximum distance of 40' from the home panel, and I use 4-0 Quadruplex cable?


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## theatretch85 (May 17, 2008)

Well you could put in a 400 amp panel at your outbuilding, or even an 800 amp panel. Your only limiting factor is your service size to the house. If you wanted the full use of the service at the outbuilding you could put in your 200 amp panel with appropriately sized wire and breaker at the house. Though in order to use the full capacity you'd have to shut off everything at the house panel. 

Depedning on how your house panel/wiring is setup, you may only be able to install a 100-125 amp double pole breaker to feed your outbuilding off your current panel. Most panels have a max circuit rating of about 100-125 amps and not to mention the size of the lugs for a breaker that size. If you really want the full 200 amps at the outbuilding, you'd be best off running your outbuilding from the pole directly.


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## AndrewF (Dec 29, 2008)

I would do something similar to what I did.

I installed 400 amp service to my house, and then am feeding two 200 amp panels in the attached garage.

100 amps of that is going out to my shop, which is 130' from the house.

I could have, and you could too, put a 200 amp disconnect at the Meter, and then ran 200 amp service to the barn.

This would then leave, 200 amps to the house and 200 amps to the garage.

I think you'd incurr extra cost to run two feeds back to the pole and I am not sure what that will gain you.


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## Code05 (May 24, 2009)

dSilanskas said:


> 5) Will the urd/use cable be ok inside the schedule 80 for this short distance inside the home and garage? *Quadruplex can be installed in pipe yes its fine. Good luck and be safe!*


Are you sure?:huh: 338.10. Pipe or no pipe, I do not think this is correct. USE/URD inside is a no no.


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## nap (Dec 4, 2007)

where do you get that?


338.10(B)(4) is defining acceptable interior installations. As a matter of fact, it refers you to NM cable installation methods.


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## Code05 (May 24, 2009)

nap said:


> where do you get that?
> 
> 
> 338.10(B)(4) is defining acceptable interior installations. As a matter of fact, it refers you to NM cable installation methods.


338.10(B)(4) specifically references SE interior wiring, not USE. Most standard USE does not have a flame retardant covering and cannot come into a building. However, I looked at Southwires site,http://www.southwire.com/ProductCatalog/proddetail.jsp?htmlpreview=true&token=12&desc=AL-RHH/RHW/USE, and the cable maybe dual rated, I cannot tell for sure. If it is I imagine an inspector will pass it, but it will have to have RHW stamped on the cable and not just USE.


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