200 Amp Underground Service 330 Feet

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crispysonofa

Senior Member
Location
New England
Occupation
Electrical and Security Contractor
Hello,

I am writing an estimate up for a residential underground service. It is a bit longer than ones that I have done in the past and I want to double check my design. The meter pedestal is going near the utility pole that is on the edge of the property. I will have a disconnect at the meter socket. I am running the underground service complete from the pole to the house.

I am thinking that I will use 3 inch conduit and 350 aluminum URD. It will be a 4 wire from the pedestal to the house because of the disconnect. Does anyone see an issue with this? I think that 4/0 is too small for the voltage drop on the run. I appreciate the insight.
 
You may need to reduce the wire to fit into your service panel at the building. Check the max size wire that will fit into the lugs.

i did not do any calculations because we don’t know the load. 200 amp residential service will never see a 200 amp load. SEWAG would be 70.
 
Thank You

Thank You

I regularly install conduit for underground services, it was how I was brought up and with how rocky the soil is here it adds some protection from the ground shifting with frost. I think you are correct on me doing a proper load calculation on the house I did my calculations based on 180 amps which is overkill. I did the calculation at 120 amps and it puts me at about 4% with a 4/0. I will look into this a bit more but I think you guys have set me straight and I appreciate it.
 
Cheap and readily available at my part houses. Either that or triplex in an aluminum, non-jacketed multiwire setup.
 
A few comments/opinions:

We usually use urd /rhh here too. It's a little cheaper and more convenient than single xhhw. I don't like direct burial here either, very rocky. One other idea, if you don't need a disconnect at meter per utility and can put your panel on an exterior wall or under a slab, you could skip the disco and run 3 wire the whole way.
 
ptonsparky said:
You may need to reduce the wire to fit into your service panel at the building. Check the max size wire that will fit into the lugs.

i did not do any calculations because we don’t know the load. 200 amp residential service will never see a 200 amp load. SEWAG would be 70.
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My house lit up like 4th of July and Thanksgiving Day and a Superbowl party all combined won't pull 70A.
 
jumper said:
You people are obsessed with rocks, I get it; but you know you could backfill with sand like I do when necessary..
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Sure. Let's line up a dump truck, a skidsteer, some guys with shovels and put a bunch of sand in the bottom of the ditch, send them home while I lay my wire in, then call them back to put some sand on top, then backfill the rest of the ditch with dirt.

Or, dig a ditch, I throw my conduit in and the backhoe can throw dirt on top as soon as I'm out of the way.

Even better than that... We have a locator and a fault finder in our shop. I go out every year and dig up a burnt up direct bury wire and patch it and charge a lot of money. Never done that on wire run in conduit.
 
jumper said:
You people are obsessed with rocks, I get it; but you know you could backfill with sand like I do when necessary..
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It not just rocks, its also someone (idiot) digging later on and hitting it, critters knawing on it, etc. Another thing is if the Al gets a knick in it, it can sit there for a long while and start deteriorating until you lose one or more legs. If it's in conduit you can re-pull it without digging a new trench or digging and trying to find the break.

I repaired one a couple of years ago as I luckily found the damaged spot, but had to completely replaced another just this week. It looked to be more than one area with damage plus a deck had been built over it making it impossible to dig there if there was damage there. Both were direct buried.
 
ActionDave said:
Sure. Let's line up a dump truck, a skidsteer, some guys with shovels and put a bunch of sand in the bottom of the ditch, send them home while I lay my wire in, then call them back to put some sand on top, then backfill the rest of the ditch with dirt.

Or, dig a ditch, I throw my conduit in and the backhoe can throw dirt on top as soon as I'm out of the way.

Even better than that... We have a locator and a fault finder in our shop. I go out every year and dig up a burnt up direct bury wire and patch it and charge a lot of money. Never done that on wire run in conduit.
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Usually I just give the grounds site crew foreman a case of beer and he takes care of it. No need to do things the hard way.
 
Where I do most of my work has a combination of Shrink Swell, Weird rocks, and fault movements on a semiyearly basis... so I always use concrete encased conduit just in case...

Watch others put in pvc water pipes and constantly deal with leaks... mine now in since 2002 and not one leak... only part of home working right ..lol...
 
crispysonofa said:
I am thinking that I will use 3 inch conduit and 350 aluminum URD. It will be a 4 wire from the pedestal to the house because of the disconnect. Does anyone see an issue with this? I think that 4/0 is too small for the voltage drop on the run. I appreciate the insight.
Click to expand...

If the URD is also RHH, RHW, Etc. 4 conductors won't fit in 3" SCH 40 PVC.
 
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