New Underground Service

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  #1  
Old 09-12-06, 08:41 AM
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New Underground Service

I need to run a 200 amp residential service entrance underground to my new home site. I will hire an electrician to make the connections but, being on a tight budget, I want to dig the trench, and lay the conduit and cable myself. My foundation is about 150' from the power company's utility pole. Can someone advise me as to the proper size and type of Conduit and cable?

Thanks!
 
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  #2  
Old 09-12-06, 08:44 AM
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The power company can. They are the ones to stipulate what you need.
 
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Old 09-12-06, 08:54 AM
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Also, talk to your electrical contractor. Don't assume that they will be willing to take your word that you installed the conduit and wire correctly. Moreover, their insurance/policies may not allow them to do work under the same permit as a homeowner. Meet with them first and get the seperation of work specified in writing to avoid a very costly mistake.
 
  #4  
Old 09-12-06, 09:01 AM
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Ya... They gave me a 150+ page "green book" that covers all of their requirements. Unfortunately, all it says about conduit and wire sizing is that it "shall be in accordance with the NEC."
 
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Old 09-12-06, 09:04 AM
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Originally Posted by mwarney
Ya... They gave me a 150+ page "green book" that covers all of their requirements. Unfortunately, all it says about conduit and wire sizing is that it "shall be in accordance with the NEC."
Then the electrical contractor who will make the final connections will need to tell you.
 
  #6  
Old 09-12-06, 09:33 AM
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Originally Posted by jwhite
Then the electrical contractor who will make the final connections will need to tell you.
So where will he/she get that information?
 
  #7  
Old 09-12-06, 10:21 AM
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Originally Posted by mwarney
So where will he/she get that information?
You have to caculate the load using the NEC requirements and
size the service conductor based on that caculation. The conduit size depends on the conductor size. The utility may have some requirements that call for a certian size and insulation type. What size is you panel? 200 amp?
 
  #8  
Old 09-12-06, 10:42 AM
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Originally Posted by wareagle
You have to caculate the load using the NEC requirements and
size the service conductor based on that caculation. The conduit size depends on the conductor size. The utility may have some requirements that call for a certian size and insulation type. What size is you panel? 200 amp?
Thank You! Yes, It will be a 200 AMP panel. I know there are theoretical calculations involved, but in reality don't most electricians oversize to be safe? I'm pretty sure it is 2/0 copper or 4/0 aluminum for 200 Amps... am I correct?

Doing more research... Looks like Schedule 80 PVC - 1 1/4" or 1 1/2" for the conduit. I will need to find an electrician to verify.
 

Last edited by mwarney; 09-12-06 at 10:58 AM.
  #9  
Old 09-12-06, 11:18 AM
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First and foremost, will the main breaker be at the pole or at the house? This determines whether or not you need to pull three or four wires into the conduit.

[QUOTE=mwarneydon't most electricians oversize to be safe?[/quote]

If the client is willing to pay for the extra copper, sure.

I'm pretty sure it is 2/0 copper or 4/0 aluminum for 200 Amps
Yes, three 2/0 copper conductors in 1-1/2" PVC80 conduit would be typical. Also acceptable would be three 4/0 aluminum conductors in 2" PVC80 conduit. Usually buried 24" or 30". Given the distance and the price of copper, the AL in 2" conduit is a pretty good option; however you should definitely have a pro review all the details of your plan before dropping any $$$ on the conduit or wire.
 
  #10  
Old 09-12-06, 11:31 AM
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Originally Posted by ibpooks
First and foremost, will the main breaker be at the pole or at the house? This determines whether or not you need to pull three or four wires into the conduit.



If the client is willing to pay for the extra copper, sure.



Yes, three 2/0 copper conductors in 1-1/2" PVC80 conduit would be typical. Also acceptable would be three 4/0 aluminum conductors in 2" PVC80 conduit. Usually buried 24" or 30". Given the distance and the price of copper, the AL in 2" conduit is a pretty good option; however you should definitely have a pro review all the details of your plan before dropping any $$$ on the conduit or wire.
Thanks for the advice Ben!
 
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Old 09-12-06, 11:40 AM
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I know It's not my money!
If you are staying for a long time go with copper (MHO). Put in a main brkr panel, I would'nt want the walk in an emergency.

Most good electricians (if they have the house, Consultants are much more expensive)) would be willing to work with you on the labor aspect of this. ASK and FOLLOW their direction and you will save a couple dollars.
 
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Old 09-12-06, 12:00 PM
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Originally Posted by lectriclee
I know It's not my money!
If you are staying for a long time go with copper (MHO). Put in a main brkr panel, I would'nt want the walk in an emergency.

Most good electricians (if they have the house, Consultants are much more expensive)) would be willing to work with you on the labor aspect of this. ASK and FOLLOW their direction and you will save a couple dollars.
Thanks for the tip! You are right... The good electricians (or any contractor for that matter) are the ones who are willing to work with you and save you money. I agree, the extra cost for copper is probably a good investment.
 
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Old 09-12-06, 12:09 PM
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You do the math. I'm not your accountant.
Think long term
AL is fine, I like copper.
If you can, do all the goodies now, Or you never will.If you don't, it will easily double from the open wall price.
Make a wish list and prioritize that list.
 
  #14  
Old 09-12-06, 12:51 PM
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The poco uses alum for their underground, price some copper lately? We have used sch 80 up and down and have used sewer pipe for the lateral if direct burial is allowed, its just a raceway for the wire. If the dissconnect is out at the pole you will need 4/0 alum, here the poco provides the wire to the meter base. Here it was 6$ a foot if they trench and they direct, we pipe and it was 3$ but they wanted 3 inch min pipe especially at that distance. One thing I do when the poco is providing the wire is get with the engineer and spec the wire ahead of time instead of letting the field crew do what they do, I can always talk them into sizing up and I get it written on the work order. My neighbor didnt think this was a big deal, he wishes now he would have paid attn, they hook the same wires from an old 100 to a new 200. At a couple hundred ft it makes a difference especially with motor starts.
 
  #15  
Old 09-12-06, 02:12 PM
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Originally Posted by mwarney
Thank You! Yes, It will be a 200 AMP panel. I know there are theoretical calculations involved, but in reality don't most electricians oversize to be safe? I'm pretty sure it is 2/0 copper or 4/0 aluminum for 200 Amps... am I correct?
Doing more research... Looks like Schedule 80 PVC - 1 1/4" or 1 1/2" for the conduit. I will need to find an electrician to verify.
1 1/2" will do the job. You do not need 3 2/0 cu. You can do some caculations and reduce the neutral to a smaller size and save some money. I would check the price of of the CU and AL.
2/0 CU is rated for 175 amps and 4/0 AL is 180. I would check with the inspector to verify that the size is ok. He may want you to goto 3/0 CU rated at 200 amps.
 
  #16  
Old 09-13-06, 03:55 AM
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Originally Posted by wareagle
1 1/2" will do the job. You do not need 3 2/0 cu. You can do some caculations and reduce the neutral to a smaller size and save some money. I would check the price of of the CU and AL.
2/0 CU is rated for 175 amps and 4/0 AL is 180. I would check with the inspector to verify that the size is ok. He may want you to goto 3/0 CU rated at 200 amps.
Thanks for the advice! Now that I think about it, I have never seen copper on a service entrance cable. Unfortunately (or perhaps fortunately) we do not have an inspector in my town. There is no zoning or codes to deal with, so we pretty much gotta figure this stuff out on our own (that is why I am here). I really appreciate all of the members who helped by providing input.
 
  #17  
Old 09-13-06, 04:43 AM
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Just installed a new service this week
(2) 2/0 copper, (1) 1/0 copper and (1) #6 copper all thhn/thwn-2 for the service cable was around $12 per foot.

(2) 4/0 aluminum, (1) 2/0 aluminum and (1) #4 aluminum USE/RHH direct burial cable was around $4 per foot.

Guess which one that I used.

New aluminum cable is made of a special alloy that compares to copper in durability and quality. The problems associated with aluminum wiring in the past have been resolved.
The insulation is the same for copper and aluminum, just depends on the rating.
Just install it right with the proper terminals and anti-corrosive paste and torque all the terminals to specification and it will give you good service.
steve
 
  #18  
Old 09-13-06, 07:52 AM
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Suggestions:

As long as you're doing conduit use a larger size Sch 80 than you need, for example 2-1/2 or 3-inch. That will make it easier to pull new when you upgrade to 3-phase for your welding shop.

Put in conduit or innerduct for phone and cable TV. I would recommend 1-1/4 or better. Then you will be ready if fiber to the home (FTTH) ever comes your way.

Get a 5-gallon bucket of cable lube and an old paint brush.

Get your pull string through before you bury.

If you or your electrician knows anybody that does a lot of underground work, check with them to see if they've got any 'reel end' innerduct available. They were giving it away five years ago but I am not sure about today. It's a lot easier than gluing PVC even if you get 20-foot lengths of Sch 80.
 
  #19  
Old 09-13-06, 11:03 AM
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Originally Posted by ArgMeMatey
Suggestions:

As long as you're doing conduit use a larger size Sch 80 than you need, for example 2-1/2 or 3-inch. That will make it easier to pull new when you upgrade to 3-phase for your welding shop.

Put in conduit or innerduct for phone and cable TV. I would recommend 1-1/4 or better. Then you will be ready if fiber to the home (FTTH) ever comes your way.

Get a 5-gallon bucket of cable lube and an old paint brush.

Get your pull string through before you bury.

If you or your electrician knows anybody that does a lot of underground work, check with them to see if they've got any 'reel end' innerduct available. They were giving it away five years ago but I am not sure about today. It's a lot easier than gluing PVC even if you get 20-foot lengths of Sch 80.
Good point... So it is "Okay" to run voice and data in the same conduit as the service?
 
  #20  
Old 09-13-06, 11:19 AM
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Originally Posted by mwarney
Good point... So it is "Okay" to run voice and data in the same conduit as the service?
Generally NO it is not a good idea. I would guess it is code-prohibited, plus you would want some separation to reduce EM interference radiating from the AC service. In WI it is OK to put AC, phone and CATV in the same TRENCH if they are direct-buried or have separate raceways, but unless your green book says different, NEC does not allow low-voltage in the same raceway with high-voltage.
 
  #21  
Old 09-13-06, 11:41 AM
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You are not allowed to put voice and data (low voltage) lines in with your service lines, or in with any electrical lines for that matter. And that wasn't suggested either.
 
  #22  
Old 09-13-06, 11:41 AM
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Originally Posted by ArgMeMatey
Generally NO it is not a good idea. I would guess it is code-prohibited, plus you would want some separation to reduce EM interference radiating from the AC service. In WI it is OK to put AC, phone and CATV in the same TRENCH if they are direct-buried or have separate raceways, but unless your green book says different, NEC does not allow low-voltage in the same raceway with high-voltage.
I didn't think so... I must have misunderstood your first post.

Thanks!
 
  #23  
Old 09-13-06, 02:57 PM
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mwarney,
I hope you have learned from the dialogue, but you are still not qualified to do a load calculation on your home, and still need an electrician to help you decide what you need. NO what you think you may want to use is not part of the calculations.

After you get all this info and get your pipe in the ground, then pull the wires, and call a licenced contractor to make up the final connections. The only type contractors you will get to take a job like this will be fly by night hacks. **************

Edit by j white. I should not have made that comment
 

Last edited by jwhite; 09-15-06 at 06:44 AM.
  #24  
Old 09-13-06, 06:11 PM
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Speaking strictly from experience..

Let the Poco run the trench and cable, you can provide the conduit _according to their requirements_. Here, SE has to be 36" minimum under ground, that means a small backhoe. The cost of renting the equipment plus trying to buy the cable yourself will be more than what the POCO will charge.

I think I paid about $500 to have it run about 200 feet, and that is certainly less than what it would have cost for equipment and materials. I ran 1.5" conduit, and the cable they used required no lube or pull rope.

While they were backfilling the trench, at 24" I ran another 1.5" conduit for phone and cable lines, and they finished filling the trench. It took them less than 4 hours, start to finish.

Yes, I could have run smaller conduit for the data lines, but 1.5" makes the pulls FAR easier (especially with other wires in the conduit), and allowed for additional (bigger) data lines in the future. The CATV installer appreciated it, and left me about 50' of extra high quaility CATV wire to make my own patch cables. The TelCo installer ran a 6 line wire instead of the normal 2 or 4 line, since he had the space.

You'd be suprised what a cold Coke on a hot Florida day will get you.
 
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Old 09-14-06, 08:09 AM
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Originally Posted by jwhite
mwarney,
I hope you have learned from the dialogue, but you are still not qualified to do a load calculation on your home, and still need an electrician to help you decide what you need. NO what you think you may want to use is not part of the calculations.

After you get all this info and get your pipe in the ground, then pull the wires, and call a licenced contractor to make up the final connections. The only type contractors you will get to take a job like this will be fly by night hacks. This may be good for you, since it looks like the cheep way out that you want.
Thanks for the advice... As I stated earlier in the post, I never intended to make the final connections myself. I'm not looking for a "cheap way out" or a "fly by night hack." On the contrary, I'm sure there are many qualified electricians who understand what it is like to be on a tight budget and that it makes perfect sense not to pay a skilled electricians hourly rate to do grunt work like pulling a cable. I have found over the years that these are actually the better contractors. They are secure in their trade and their abilities, and they do not feel threatened because a home owner wants to save some money. The contractors I avoid are the obviously insecure ones who feel the need to keep their trade a secret, or the ones who think that all home owners are idiots and canít do anything themselves. I come here looking for advice because it is a Do-It-Yourself forum. However, it seems like the only input I get from moderators is that I should not Do-It-Myself. Please take my advice in the positive spirit it is given. If you view your customers as incompetent fools, they will sense this and resent you for it.
 
  #26  
Old 09-14-06, 08:13 AM
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Originally Posted by Pendragon
Speaking strictly from experience..

Let the Poco run the trench and cable, you can provide the conduit _according to their requirements_. Here, SE has to be 36" minimum under ground, that means a small backhoe. The cost of renting the equipment plus trying to buy the cable yourself will be more than what the POCO will charge.

I think I paid about $500 to have it run about 200 feet, and that is certainly less than what it would have cost for equipment and materials. I ran 1.5" conduit, and the cable they used required no lube or pull rope.

While they were backfilling the trench, at 24" I ran another 1.5" conduit for phone and cable lines, and they finished filling the trench. It took them less than 4 hours, start to finish.

Yes, I could have run smaller conduit for the data lines, but 1.5" makes the pulls FAR easier (especially with other wires in the conduit), and allowed for additional (bigger) data lines in the future. The CATV installer appreciated it, and left me about 50' of extra high quaility CATV wire to make my own patch cables. The TelCo installer ran a 6 line wire instead of the normal 2 or 4 line, since he had the space.

You'd be suprised what a cold Coke on a hot Florida day will get you.
Thanks for the input. I already asked the Poco but they do not run underground. They will only run overhead. So it sounds like you ran the service and Voice/data in the same trench but with separate conduit at different depths?
 
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Old 09-14-06, 08:19 AM
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Originally Posted by racraft
You are not allowed to put voice and data (low voltage) lines in with your service lines, or in with any electrical lines for that matter. And that wasn't suggested either.
Yes... As I said, I misread the other post. I apologize.
 
  #28  
Old 09-14-06, 08:35 AM
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Originally Posted by wareagle
2/0 CU is rated for 175 amps and 4/0 AL is 180. I would check with the inspector to verify that the size is ok. He may want you to goto 3/0 CU rated at 200 amps.
NEC Table 310.15(B)(6) Conductor Types and Sizes For 120/240 Volt, 3 Wire, Single Phase Dwelling Services and Feeders. Conductor Types RHH, RHW, RHW-2, THHN, THHW, THW, THW-2, THWN, THWN-2, XHHW, XHHW-2, SE, USE, USE-2.

#2/0 Copper........200 Amps
#4/0 Aluminum.....200 Amps

You can only use these numbers (ampacities) for Service Entrance Conductors (From the Meter to the Main Disconnect), Service Lateral Conductors (underground service from the Meter to the Main Disconnect), and Feeder Conductors [from the Main disconnect to the Lighting and Appliance sub-panel(s)] that serve as the main power feeder conductors to each dwelling, They must be installed in a raceway (conduit) or cable.
steve
 
  #29  
Old 09-14-06, 04:02 PM
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Originally Posted by mwarney
Thanks for the input. I already asked the Poco but they do not run underground. They will only run overhead. So it sounds like you ran the service and Voice/data in the same trench but with separate conduit at different depths?
Right. According to our local requirements, service cable must be at least 36" below grade, others must be at least 24". They can be in the same trench, seperated by at least 1', just not in the same conduit (and you wouldn't want them to be).

It was an expense, but it's a one time expense, and I think the place looks better without 3 or 4 cable drops running overhead.

Now, if they would just run the street wires underground...
 
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Old 09-14-06, 04:18 PM
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Each area is different regarding POCOs'
Here they will run the overhead to your weatherhead. Underground to their hand hole.you run to meter.
Go to ME. they run it to the line side of meter.
So always ask, you never know.
 
  #31  
Old 09-15-06, 05:01 AM
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Where I live the POCO will supply the wire for a underground service (and hook it up to their meter or your outside meter main), the customer supplies the trench and backfill.
Overhead, they will run to your connection on the house and attach to your service cables.
steve
 
  #32  
Old 09-15-06, 07:09 AM
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Here the overhead is free in most cases and there are 2 rates for underground. For 6$ a ft they will direct bury it and its 3 if you have it piped. As for this service 2 inch is too small for that distance for my tastes and that size wire. I would tend to believe there is some kind of inspection system everywhere in the country. I cant see how the power co would heat up a service without it. They are the only game in town, there is no reason they would do it without one. They would stipulate it as a condition to turning the power on.
 
  #33  
Old 09-15-06, 08:39 AM
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Remember, if the meter and disconnect is at the house not only will the wire have to go to their pole but up it as well all the way to the kettle.
 
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