Underground power line - conduit or bare cable?

[BellyUpFish]

Hey guys-

We are getting ready to start a new home build. This will be our first "lot to home" build and I've got a question regarding the power.

We're planning on running 1,000' off the road to the house. So power, water and gas will all need to run this 1,000' feet.

We'd like to run underground power to keep from cutting down trees. The paperwork given to us by the utility department states the the owner is responsible for "conduit or trenching."

So, I'm going to have to either rent a trencher or hire someone to run the trench. No issues there.

My biggest questions are:

Can I just throw bare power line into the trench or is conduit required?

Can I run power, water and gas in the same trench?

If the power line can be installed in the ground bare, what are the benefits of putting the line in a conduit?

Thanks

 

[Pluribus]

Your power company likely has a free manual that details types of services and trench depths, fill, spacing between other utilities, conduit/direct bury, etc. Any answers you get on here that don't reference your electric might not be relevant. I recommend a call to your electric company; bet they are willing to mail you the information.

 

[CNGsaves]

Get the appropriate information from local authority / PoCo / gas company / telephone company. I would be surprised they would allow "Shared Trench" for electric & NG.

THEN go to neighbor's house who has done the same thing already and "talk shop" about how their process went for burying utilities. You can't be first person in area dealing with the overhead vs buried decision. No point in re-inventing the wheel !

With those distances I'm guessing you'll be electric with a propane tank. Let us know how this turns out and how you get any internet service at that location. Good luck.

 

[aandpdan]

It can be done in some places, gas, water and electric in the same trench. Your AHJ and utilities should have that info.

Why use conduit when you can use direct bury? Because if there is ever a cable fault, and they do happen, you don't have to dig anything up. You just pull out the old and run in the new. Use conduit larger than required - it's cheap.

 

[nick2010tundra]

As a Lineman I would love to give my opinion here. I have gone to far to many houses in the middle of the night where they have lost a leg or completely lost power in the freezing cold. Most times a rock will work its way thru the sand from frost and hit the wire, then it starts to chafe and finally starts burning up.
Now say you do a perfect job with your trench and its in sand, That's great but when its time to replace the wire what do you have to do.
I've watched people struggle to find an electrician to fix the wire on those cold nights where a shovel won't even break the ground. If it was in pipe you can pull the new in with the old.
Problem is when Contractors are building houses they don't care if it saves them money, the problem is down the road 5 or 10 years. Long after they have been payed

IF it was me I wouldn't hesitate if its your forever home, small price to pay for reliability

 

[G McKay]

I would use conduit if it were me. You might even want to run (and leave) a small chain through the pipe in case you ever have to feed something through it. We have done this at work where underground lines were constantly breaking.

 

[kbs2244]

There are people that would have you put a man hole at the road end and then run 6 inch pipe into you basement.
Lots of access room and lots of room to run wire and pipe.
I used to be one of them.

But I have learned that the possibly of ever needing all that is pretty low.
There are literally millions of direct burial power, natural gas, phone and TV wires feeding homes across America.
They wouldn’t do it that way if the numbers didn't work out.

If you want to be prepared for a rare need, lay length of the 4 inch, non-perforated, corrugated pipe on top of the normal stuff in the trench. Maybe run a length of poly rope through it. Cap the ends and bury it. If you ever need it then it will be there waiting.

 

[ddawg16]

I would run PVC out to the road for compressed air in case you get a flat out there.

Seems to me the cost of conduit and THWN wire vs direct burial cable would be the deciding factor.....as well as what are the chances of damage.

But if you're going to do a trench....put a spare conduit in there for cable, Ethernet, what ever.

Bury it deep.

Do it right....do it once.

 

[NUTTSGT]

Inquire with the local PoCo as to what they allow. Locally one of them requires conduit while the other will allow you to bury the incoming power in 4" field tile.

 

[Stuart in MN]

Where is the utility transformer going to be located? Right up by the house, or somewhere in between there and the road? The utility will dictate what is done between the road and their side of the transformer.

 

[Cmreschke]

Typically around here the power company provides the wire you would just provide the trench, they are putting in their wire in your trench or conduit doesn't matter to them. It is the same wire,
The lineman brings up a good point about the rocks and what not, but if your not below the frost line it doesn't help in the winter time as the conduit will have water in it that freezes so the point is go deeper than frost line.

 

[hh76]

I've done some contract work designing for a utility company, and I can tell you that a lot of the advice given so far is bad.

The only good advice is to ask the utility exactly what they need.

For one thing, they won't be running secondary voltage 1000', so where will the transformer be located? What size and type of conduit?

 

[BellyUpFish]

Thanks for all the replies guys..

This is my first go at this, so I'm pretty ignorant on most of it.

I have no idea what size wire, where the transformer will be located, etc..

I'm meeting with the city engineer in a few weeks.

Internet will be DirecTV.. :/

 

[gungatim]

In my state, the power company runs the lines without any conduit, just ground contact wire/cable. You are responsible for the trenching, but they will do it and just charge you by the foot. This is Consumers Energy. When I built my house, they had previously put up the pole and ran underground power for the previous build that was never completed. I demo'd and built a new home but wires were 12 ft. too short. They put in an underground splice after I dug the short trench...

and yes, you don't want to run 1000', let them put up the poles, then run from the last pole to your house.

 

[BellyUpFish]

Our power company does basically the same thing.

I'm responsible for the trenching. First 300' is "free." We are going to try and run poles for that 300' and then go underground.

I don't want to run power poles across my parents backyard and ruin their view.

 

[theoldwizard1]

We're planning on running 1,000' off the road to the house. So power, water and gas will all need to run this 1,000' feet.

We'd like to run underground power to keep from cutting down trees. The paperwork given to us by the utility department states the the owner is responsible for "conduit or trenching."

But it does NOT say you are responsible for providing the cable !

Get that clarified IN WRITING !

Can I just throw bare power line into the trench or is conduit required?

The proper cable type can be "direct buried".

Can I run power, water and gas in the same trench?

MAYBE !

You need to talk to the local building inspector/code enforcement. Some places yes, Some places no. If yes, I'm certain you will have to make your trench deeper and that there will be a minimum requirement for earth between each of these services and which has to be lowest/highest in the trench.

Save yourself some future headache by burying a plastic marker strip (like yellow CAUTION tape) about 1' below ground. Hopefully that will be dug up first before anyone goes deeper.

If the power line can be installed in the ground bare, what are the benefits of putting the line in a conduit?

None that I know of. Might be a requirement for multiple services in the same trench.

 

[theoldwizard1]

The only good advice is to ask the utility exactly what they need.

and GET IT IN WRITING !

I would even go so far as to review it with the building inspector (or who ever has the final say so) to make certain he agrees.




I had a buddy whose lot passed a perk test, but another county department would not approve his septic field until it was redesigned as a "raised bed" septic field. You have to give "the man" what he wants !

 

[theoldwizard1]

When you are talking to the power company, find out (IN WRITING) what type of service they are going to provide (200A, 250A ?) at the meter and ask what it would cost to go up to the next level.

You also want to know (IN WRITING) who is responsible for maintaining that cable.

 

[monkeyplasm]

Ask all the utilities independently about "Joint Trench" requirements.

 

[Aceman]

Your question is too vague. First things first, if you're going to do this yourself, you need to know what EXACTLY you're responsible for and where the transformer is going. What is the power company's scope and what is under your scope? Look online if you have too, most power companies have a pdf of their service requirements manual.

Over here, one power company we run the primary and secondary conduit to the transformer, they install all the wire.

Another power company, we install the primary and secondary conduit, but are responsible for installing the secondary wire and hooking it up at the service, but not the transformer.

In your situation, I'd want them to run primary underground to a padmount transformer somewhere near the house. That would cut down the VD issues as well as putting the maintenance of the 1000' run as their responsibility and not yours.

 

[wyliesdiesels]

I've done some contract work designing for a utility company, and I can tell you that a lot of the advice given so far is bad.

The only good advice is to ask the utility exactly what they need.

For one thing, they won't be running secondary voltage 1000', so where will the transformer be located? What size and type of conduit?

As i read through all the comments i was about to hit reply and respond with what you are saying.

I would bet money that most of that 1000' will be primary wire to a padmount transformer since the OP doesnt want to cut trees down or have unsightly poles put up. Voltage drop over 1000' with secondary wire would be such an issue that very large parrallel conductors would have to be used.

 

[Charles (in GA)]

Around here, GA Power does their own trenching, even secondary from transformer to meter.

With a 1000 ft run, the transformer is certain to be mounted close to the house on a slab and a primary run from the road to it. I have overhead secondary supplying the whole subdivision running the length of my yard (comes in the back, runs the property line to the street, about 800 ft, then runs down the street, all overhead. My house power comes off, amazing enough, at the pole at the street, and a primary runs underground back to the transformer between me and the neighbor, on the other side of the lot from the main feed. The primary almost completely encircles me!.

When I did the shop power, we dropped down the pole (transformer was already there for a yard light) next to the house, and ran the 100 ft or so to the shop meter underground . Don't know why the house was not done that way.

In the case of the shop, it took an underground crew to trench and run the underground, and the next day an overhead crew ran it up the pole and connected it to the transformer........ specialization!!!!!

Charles

 

[alfredeneuman]

The first step is to call the Utility Company and get their take on it.

They will be able to tell you all you need to know.
Any answers here are just speculation

 

[BellyUpFish]

I need to get with the engineer.

The paperwork the utility department gave us is extremely vague.

 

[davetulk]

http://www.florenceutilities.com/Utilities_Departments/Electricity/Engineering_Drawings/UGSPEC.pdf

That is Florence underground specs.... Did a google search.

However that is there standard specs. With 1000' they will have to engineer the solution, transformers etc. That will give you the answer over what they will let you do.

http://www.florenceutilities.com/Ut...TION REQUIRED FOR NEW RESIDENTIAL SERVICE.pdf

That is what info they need to for new residential service.

and this is the page with their engineering drawings:

http://www.florenceutilities.com/Electricity_Department/Engineering_Drawings/index.html

Dave

 

[hh76]

Are you going underground? you showed specs for an overhead service?

Were you talking about supplying the overhead service mast, or an underground service cable/trench. Two totally different animals.

Talk to the utility.

 

[BellyUpFish]

Are you going underground? you showed specs for an overhead service?



Were you talking about supplying the overhead service mast, or an underground service cable/trench. Two totally different animals.



Talk to the utility.

Wow.. It's been a long day.. Sorry about that..

I am going to talk to them. I have to meet with a city engineer before anything happens anyway. I was just attempting to educate myself about this before I spoke with him..

More vagueness from the utility department, but the correct page this time..

 

[hh76]

Wow.. It's been a long day.. Sorry about that..

I am going to talk to them. I have to meet with a city engineer before anything happens anyway. I was just attempting to educate myself about this before I spoke with him..

More vagueness from the utility department, but the correct page this time..

Not really all that vague, just can't give the specifics that will be determined by the service length/size.

What they are saying is that it is up to the customer to do the trenching and placement of the conduit for the service portion.

When you apply for the service, they will probably have someone take a look at the property to determine what they need, and placements. Once they know that, they will communicate with you size and locations for the conduit.

Around here, primary power lines and transformers placed on customer's property require easements, and location of them can be negotiated (costs will vary with different locations).

Keep in mind that they do this all the time, and have worked with many customers like yourself in the past. Ask lots of questions, and make sure that you fully understand what they are asking of you.

 

[BellyUpFish]

Ask lots of questions, and make sure that you fully understand what they are asking of you.

Oh there will be plenty of that. I'm a goose in a rainstorm, ATM. LOL

 

[nick2010tundra]

Unless they have too they won't run underground primary or high voltage ( that cable is way more expensive

They pay for 300 feet so get them to run overhead for the first 700 or 800 feet and then hang a pot and do the rest underground.

Now my comments
300 feet is not even close to far for 4/0 for the utility, That's why they limit at 300 feet
Average transformer feeds 4/0 secondaries 2 poles each direction with 5 or 6 200 amp entrances with zero issue. Different rules for houses as compared to utility.

Now My advice again

Call the utility and get them out there for a talk on site, they will be able to give you a cost and plenty of ideas

Any other questions feel free to pm me, a map of the property might help too

 

[BellyUpFish]

I'm planning on running above ground as far as I can in order to not ruin my parents view.

My father split some land between my sister and I.

Where I'm building, will run right through my mothers "view."

I won't ruin that, so it'll be underground from there.. Hoping ~500ft or less.

I'm getting with the engineer as soon as the perc test is complete..

 

[hh76]

In my experience designing utility lines, underground primary is slightly cheaper than a pole line assuming you can plow or trench it in.

 

[logixjock]

As a Lineman I would love to give my opinion here. I have gone to far to many houses in the middle of the night where they have lost a leg or completely lost power in the freezing cold. Most times a rock will work its way thru the sand from frost and hit the wire, then it starts to chafe and finally starts burning up.
Now say you do a perfect job with your trench and its in sand, That's great but when its time to replace the wire what do you have to do.
I've watched people struggle to find an electrician to fix the wire on those cold nights where a shovel won't even break the ground. If it was in pipe you can pull the new in with the old.
Problem is when Contractors are building houses they don't care if it saves them money, the problem is down the road 5 or 10 years. Long after they have been payed

IF it was me I wouldn't hesitate if its your forever home, small price to pay for reliability

Had this exact thing happen at my house, the PO cheap'd out on the service feed, (and everything else). Conduit is the only way to go if you are running under a gravel driveway.