# What size conduit for service entrance?



## Buzz Saw (Aug 13, 2015)

Howdy,

I'm running underground  electrical service to a new pole building, what size conduit should I use for Aluminum 4/0 4/0 2/0 (I think that is the size for 200 amps)service cable?  2", 3"?

Thanks


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## begreen (Aug 13, 2015)

2"


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## Buzz Saw (Aug 13, 2015)

Will 2" be a hard pull for 100'?

Should I pull the cable through the conduit then put it in the trench?


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## begreen (Aug 13, 2015)

Yep, for that long a run 3" will make it easier. Not sure but check to see if this requires an increase in wire size for that length. I think 100' is the max for 200a with 4/0 alum. but it's been a long time since I looked at wire tables. When in doubt, ask the inspecting authority.


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## Highbeam (Aug 14, 2015)

Power company requires 3" for the 200 amp feed to my house. Conduit is cheap, and hard pulls are no fun. Pull the wire after the conduit is assembled, the glue does not play nice with the wires.


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## velvetfoot (Aug 14, 2015)

Even HD sells cable lube, or whatever it's called.  That might help.


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## Buzz Saw (Aug 14, 2015)

Well we have no local inspecting authority,  however the power company "engineer" said minimum  of 2" is what they use.  He also said thier underground runs are normally 10'-20'.

You guys ever used field tile as a conduit? My father swears by it.


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## Buzz Saw (Aug 14, 2015)

He swear by it because it's cheap, not sure how it compares to conduit


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## begreen (Aug 14, 2015)

Buzz Saw said:


> Well we have no local inspecting authority,  however the power company "engineer" said minimum  of 2" is what they use.  He also said thier underground runs are normally 10'-20'.
> 
> You guys ever used field tile as a conduit? My father swears by it.


No electrical inspector in your area? Yikes, that could get scary. Go 3", 100' is a long run.


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## Buzz Saw (Aug 14, 2015)

Things are pretty relaxed in my county.  It's pretty rural and the only "big city" is the county seat.

We don't have building permits either, just zoning permits ( for tax purposes)


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## begreen (Aug 14, 2015)

The idea of any Joe wiring a house is scary. This is definitely a place where a little knowledge can be a dangerous thing. Our house got a remodel in 1984 and the wiring was atrocious. Our previous house had the whole kitchen, outlets and all wired off of an old 40 amp range circuit!


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## Hogwildz (Aug 14, 2015)

Highbeam said:


> Power company requires 3" for the 200 amp feed to my house. Conduit is cheap, and hard pulls are no fun. Pull the wire after the conduit is assembled, the glue does not play nice with the wires.


I'm with you on this one, larger is def better, and the cost difference is nominal compared to the ease between the 2" and 3". No brainer.


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## begreen (Aug 14, 2015)

Highbeam said:


> Power company requires 3" for the 200 amp feed to my house. Conduit is cheap, and hard pulls are no fun. Pull the wire after the conduit is assembled, the glue does not play nice with the wires.


Our 200 amp conduit is 2" but it's a short run.


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## hockeypuck (Aug 16, 2015)

Go 3" .. there is special wire for underground service pulls.   Some utility companies require a galvanized 90 degree sweep (as opposed to PVC) to handle the long pull.  Ask for "USE" rated wire at you local electrical house.  Definitely get you utility out there before doing anything.   Be nice.. they could make your life miserable.


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## kennyp2339 (Aug 16, 2015)

I am a utility worker and we required 3" schedule 40 grey for 4/0al tpx  - be advised that the 4/0 has a load amp rating at 180amp @ 240volts - (That a lot of power) considering your probably being fed from a 25kva (or less) transformer. A 25kva will give you approx. 128 full load continuous amps before it boils out and "blows"


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## HitzerHillbilly (Aug 19, 2015)

kennyp2339 said:


> I am a utility worker and we required 3" schedule 40 grey for 4/0al tpx  - be advised that the 4/0 has a load amp rating at 180amp @ 240volts - (That a lot of power) considering your probably being fed from a 25kva (or less) transformer. A 25kva will give you approx. 128 full load continuous amps before it boils out and "blows"


I'm also a utility worker, been doing line work about 8 years, 3" is much better for the little cost increase. We put in a lot of 4/0 triplex. I've seen it run almost 400 ft. ...although I Wouldn't recommend that!


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## kennyp2339 (Aug 19, 2015)

400ft - it's all dependent on load and voltage, generally we don't like going past 300ft, if it is a longer run we either bump up to the next size wire 350al, or primary extension


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## HitzerHillbilly (Aug 19, 2015)

kennyp2339 said:


> 400ft - it's all dependent on load and voltage, generally we don't like going past 300ft, if it is a longer run we either bump up to the next size wire 350al, or primary extension


Running a small shop, I agree with 300 ft. I think past that is pushing voltage drop issues. As far as I know it's been ok for the guy though. Around here we have to be within a certain percentage of 120 / 240 volts.


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## HitzerHillbilly (Aug 19, 2015)

Or whichever voltage they require


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## HitzerHillbilly (Aug 19, 2015)

So where ya out of Kennyp, didn't know there was anyone else in the line industry on here?


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## burnham (Aug 19, 2015)

2" is fine.  3" is stupid.  If anything you could go 2.5", but you don't need to.   I've installed tens of thousands of feet of 4/0 sweetbriar in 2" conduit, with some runs going over 300', with no problems.


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## Buzz Saw (Aug 20, 2015)

Menards 2" sch 40 is around $5 per 10'.  2.5" is like  $14. Per 10' and 3" is $13 per 10'.  

So that means 2.5" is out but 3" is  is 2.5 times the price of 2".  The short run is about 85' and the long run is 160'.  

I'll have to do some more price shopping at some local supply houses.  Hopefully I can get some better pricing if I buy everything at once.


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