LOOONNNGGG Underground Cable Run

[robiefield]

I've got a huge job coming up, and I could use advice on technique.

After years of petitioning, the Power Company has consented to provide electricity to my isolated acreage in the VA mountains.

I have agreed to trench 36" underground from my service drop location to the nearest power pole, and put in 3" conduit with pull rope so that when the Power Co comes, they only need to pull the main feed (600A) cable from the nearest pole to my service drop.

Here's what makes it interesting: This is not going to be like pulling Cat5 through 40-50 feet. It's going to be a 1500 foot-long distance. With BEEG honking cable. Power Co has to pull the cable (thank Dog) but what is the best way to set up rope to pull through 1500 feet of 3" schedule 40 electrical conduit in a trench?

How do the pros do this? In 30 50-foot segments? 15 100-foot segments? Clearly I can't get a 1500 foot rope (and if I could, can you imagine trying to pull a cable that big that far? Ay yi yi...)

If I want the PowerCo guys to be able to work uninterrupted, do I need 30 50-foot ropes? What seemed conceptually simple (how hard can it be, you thread rope through a 3" pipe) becomes not so simple when I get to the details.

Who's been there? What's the right way to do this (besides subbing the job out)? I'm all ears, friends. Can you help me figure this one out?

 

[moeh1]

Haven't pulled that far, so no help. I'd recommend you use schedule 80 conduit at each end where you come up, so you have less to worry about.

 

[robiefield]

Useful information: the 1500 foot run is for all practical purposes straight and can be accomplished using only 10 foot long straight electrical PVC conduit pipe.

Also am I correct in thinking that Sch 40 PVC Elec conduit (flared at one end, no connectors required) can be press fit when joined, or should I plan on gluing 150 junctions together during the process?

The PowerCo will pull the cable and do the connection work so I am not trying to play with electricity that I should not be fooling with. I am just a dyed-in-the wool DIY guy who isn't afraid of doing tedious dirty work in lieu of paying someone to do tedious dirty work. If I can understand the proper technique, I don't think I need 20 years of experience to thread a rope through empty 3" pipe a few feet at a time.

I *do* need the advice of someone with experience about what type and size of rope to use, and what lengths to use, and how to string together the individual segments, assuming that one 1500 foot rope pull is not realistically feasible.

I'm not the smartest guy in the world, but I learned to follow instructions pretty well in engineering school.

 

[robiefield]

I'd recommend you use schedule 80 conduit at each end where you come up, so you have less to worry about.

I can see the logic behind that. Sch 80 for the whole run would be breathtakingly expensive and overkill, but I can see where the 90 ells at each end (and possibly the single length of vertical conduit exiting the ground at each end) being Sch 80 making sense.

I'd imagine the 90 ells at each end would only be added after the long straight run has had the cable pulled through. No sense in making the job harder by putting the ells on until after the long haul is pulled.

I recollect Sch 40 and Sch 80 have common OD but Sch 80 is thicker and has a smaller ID than Sch 40. It makes me wonder if 3" Sch 80 ells would properly fit to a 3" Sch 40 run...

 

[RippySkippy]

snipped...

Also am I correct in thinking that Sch 40 PVC Elec conduit (flared at one end, no connectors required) can be press fit when joined, or should I plan on gluing 150 junctions together during the process?

I wouldn't take the risk of NOT gluing the joints, when the pipe is assembled on grade, then lowered into the trench, it will take no time at all to do it and do it correctly. One of the first calls I would make is to a electrical supply shop and see if you could locate 20' sticks...half the joints and fuss. Here's the Carlon part numbers...

... I learned to follow instructions pretty well....

I'm with ya.....

 

[RippySkippy]

... makes me wonder if 3" Sch 80 ells would properly fit to a 3" Sch 40 run...

Specs for fittings...

 

[Just Bill]

Why don't you have more poles set?
1/4 + mile is a long way to pull cable especially 600a.
I would prime and glue the joints to keep the water out.
Call the power company and ask what is needed.
Too small might be a wreck but too large would be a waste of money.

 

[Danno1]

.


How about putting pull boxes at 500 and 1000 feet? Rope comes in 600 ft rolls. Either that or learn how to splice rope.

Also, I think I'd check w the elco to see what size/type of rope they want to find in there.


.

 

[tcartwri]

If it's direct burial cable, you can use drainage pipe instead of 150 pieces of shedule 40.

Personally, I would find out what they specify for poles and have a seperate contractor put them in, with a transformer at your end.

 

[oldnslo]

Conduit comes in spools so there would be a lot less joints. My son worked for a directional boring company and they pulled up to 6" conduit in 500 ft lengths. Might want to do a little checking around with electrical supply houses etc. They also have rope/line made for pulling cable.

I would also check with your electrical company because here the code calls for steel elbows at both ends for that size wire.

Roy