in ground pull points

[kaffine]

I am looking at burying some conduit. The problem is the route I am looking at requires 540 degrees of bends. There will be 2 conduit runs 1 for power one for comm. each will be 2 inch pvc. What is allowed for in ground pull points?

Does it make a difference if the wires just pass though vs being spliced? The power side I would be running 2 awg aluminum wire. The comm side will likely be 12 strand fiber and possibly some coax. It would be easier if I splice the wire at the pull point at least for the power but could be done without splicing.

Has anyone used HDPE conduit? I'm trying to get pricing on it to see how it compares to PVC cost wise. It would be nice no to have to glue all the joints.

Thank you.

 

[Higgins]

When we installed the power to the 2nd garage panel, we rolled out the aluminum wire to straighten it out.
For convenience sake, we started at the power pole and slipped the aluminum wire thru the 2" PVC one piece at a time, then slipped in the 90's as we went. once everything was basically in place, we went back and glued the pvc together, and the pvc was stubbed into the bottom of the meter housing......

Don't know how tight of turns you need to make, but you may be surprised at how flexible the 2" pvc can be over distance! As our run was around 300 ft

AL

 

[Charles (in GA)]

When we installed the power to the 2nd garage panel, we rolled out the aluminum wire to straighten it out.
For convenience sake, we started at the power pole and slipped the aluminum wire thru the 2" PVC one piece at a time, then slipped in the 90's as we went. once everything was basically in place, we went back and glued the pvc together, and the pvc was stubbed into the bottom of the meter housing......

Don't know how tight of turns you need to make, but you may be surprised at how flexible the 2" pvc can be over distance! As our run was around 300 ft

AL

Code requires the conduit be in place and completed prior to the pulling of wire. Probably insures that if you can get it in, you can get it out.

Code also specifies no more than 360 degrees of bends between pull points.

Charles

 

[Speedy Petey]

I am looking at burying some conduit. The problem is the route I am looking at requires 540 degrees of bends. There will be 2 conduit runs 1 for power one for comm. each will be 2 inch pvc. What is allowed for in ground pull points?

They sell in ground pull/splice boxes boxes. Many times they are open bottom where you just line the bottom of the hole with smalls so water drains.

Does it make a difference if the wires just pass though vs being spliced? The power side I would be running 2 awg aluminum wire. The comm side will likely be 12 strand fiber and possibly some coax. It would be easier if I splice the wire at the pull point at least for the power but could be done without splicing.

You don't have to splice. The wire can just pass through.

Has anyone used HDPE conduit? I'm trying to get pricing on it to see how it compares to PVC cost wise. It would be nice no to have to glue all the joints.

I've never seen HDPE electrical conduit in use or even for sale. Is it threaded? If so then IMO threading together is just as much work as gluing.
How long is the run that this is even a consideration?

 

[Higgins]

Thanks Charles, Interesting point!

We had 2 options in installing the feed. Either the local power company, or we could do it!

As it was 2 ole retired farts installing the cable, and it was heavy...... they suggested how to install the cable as we didn't have any of the fancy ropes, cables and power units to pull the power feed in! However, we only had 3 90's.

They inspected the install in the trench before it was backfilled, and local inspector was OK with it!

AL

 

[Gooch]

I've never seen HDPE electrical conduit in use or even for sale. Is it threaded? If so then IMO threading together is just as much work as gluing.
How long is the run that this is even a consideration?

HDPE conduit aka "Ridged on a reel".


It's used mainly with bores rather than open trench. It comes on huge reels(trailer required) and comes in lengths up to 500'

 

[Slick6]

HDPE aka "Innerduct"

Do a google search for "plastic hand hole", you should find something to suit your needs.

On a side note, you mention pulling 12 strand fiber for comm. Is this for a residential application or commercial?

 

[Stuart in MN]

Hubbell/Quazite is one popular brand of in-ground pull boxes but there are others, check with your local electrical supply house to see what is commonly used in your area: http://www.hubbellpowersystems.com/enclosures/below-ground/default.asp HDPE conduit can be ordered with the conductors already installed, although I don't know if there are minimum lengths - it's usually done for long distance installs where the HDPE is installed by directional boring or with a vibratory plow.

 

[ishiboo]

HDPE aka "Innerduct"

Do a google search for "plastic hand hole", you should find something to suit your needs.

On a side note, you mention pulling 12 strand fiber for comm. Is this for a residential application or commercial?

Nah, innerduct is not for direct burial.

As Gooch said, it's commonly used for boring and you'll see it at practically every low-voltage underground communication jobs. Thick, orange conduit. The HDPE like nylon is "oily" and easier to pull, flexible, and quite tough.

I've never seen it for a small high-voltage job, it might be easier to pull the cable through but that much. It will be VERY difficult to work with in the size needed as it has a significant "memory" to staying in the coil it came in

Another reason for not gluing the PVC before pulling is that the wire insulation inside is often PVC is the insulator in wires like THHN, get PVC cement on the stuff and it gets glued to the pipes/etc. Then move it around a bit and you start tearing insulation off. THHN has nylon over it but that's often nicked, and I'm not sure it's resistance to PVC cement.

 

[kiatech]

I would not use interduct. That stuff is a pain to use.

 

[Slick6]

Nah, innerduct is not for direct burial.

It most certainly is. I guess I should have been more specific with regards to the main two types of innerducts (there are more); smooth wall and corrugated. Yes, both are HDPE, and both are innerduct.

 

[1/2 Cup]

We use inground pits, to assist pull through and to do transitions in this neck of the world.

 

[OldNeons]

Not sure what length you are pulling, but 540 is too many bends. Can you get an electric heater and make some sweep bends or use some 22 or 45s to cut down on overall bends? Glue all pipe first first, pull a twine through with a foam mouse then drag a rope back through with the twine. Plan ahead so u can have all the cable laid out straight and use plenty of lube. Get a Chinese handcuff "sock" for cable end then tape the heck out of it and lube it up good. When we were pulling cable, one guys job was to sit at conduit opening and keep putting lube in, can't underemphasize that! If you can't rent a tugger (winch) then you better have a bunch of friends. Besides pullers you need guys on feeding end keeping conductors up on their shoulders and keeping it pushed into duct as others are pulling.....

Another totally different option is direct bury aluminum feeder conductors?

It's not fun but you can do it!

 

[kursplat]

any place you can have a handhole to pull through in place of a 90 you'll be much happier. might want to get some cable snot, or just use real soapy water, to make the pull easyer

...Another reason for not gluing the PVC before pulling is that the wire insulation inside is often PVC is the insulator in wires like THHN, get PVC cement on the stuff and it gets glued to the pipes/etc...

maybe i miss read this, but how would you glue all the joints after the pull?

 

[Higgins]

We glued most of the pvc after we pulled the power feed thru it!! The long straight runs were glued ahead of time, fed the cable thru all the PVC and 90's, got the end at the meter housing, then went back and glued the 90's in place!

Wasn't a problem for me! It was two ole farts doing it by hand, and we didn't have any additional help, winches, etc..... and it worked for us! CoEd was happy as was the local inspector............

However, in Colorado, I had a 500 ft feed, and used our Jeep to pull the cable in. But in that case, it was almost a straight shot!!

AL

 

[kaffine]

Thanks for the replies.

Not sure what length you are pulling, but 540 is too many bends. Can you get an electric heater and make some sweep bends or use some 22 or 45s to cut down on overall bends? Glue all pipe first first, pull a twine through with a foam mouse then drag a rope back through with the twine. Plan ahead so u can have all the cable laid out straight and use plenty of lube. Get a Chinese handcuff "sock" for cable end then tape the heck out of it and lube it up good. When we were pulling cable, one guys job was to sit at conduit opening and keep putting lube in, can't underemphasize that! If you can't rent a tugger (winch) then you better have a bunch of friends. Besides pullers you need guys on feeding end keeping conductors up on their shoulders and keeping it pushed into duct as others are pulling.....

Another totally different option is direct bury aluminum feeder conductors?

It's not fun but you can do it!

I am looking at putting a pull point in the middle to keep it under 360 degrees. If I go with PVC I will be using the largest radius 90 degree IMC elbows I can get. I will be grounding the ones coming out of the ground. I have thought about direct bury for the power but prefer conduit. The comm. cable will be conduit.

Hubbell/Quazite is one popular brand of in-ground pull boxes but there are others, check with your local electrical supply house to see what is commonly used in your area: http://www.hubbellpowersystems.com/enclosures/below-ground/default.asp HDPE conduit can be ordered with the conductors already installed, although I don't know if there are minimum lengths - it's usually done for long distance installs where the HDPE is installed by directional boring or with a vibratory plow.

Do you know if you are still limited to 360 degrees between pull points if the conductors are already in the conduit?

HDPE aka "Innerduct"

Do a google search for "plastic hand hole", you should find something to suit your needs.

On a side note, you mention pulling 12 strand fiber for comm. Is this for a residential application or commercial?

It is residential. The problem is the run is too long for Ethernet over copper. I either go fiber or I have to put a repeater in somewhere. The reason for 12 count is I have a few other signals that don't like long distances and it is easier to convert them to fiber than Ethernet.

They sell in ground pull/splice boxes boxes. Many times they are open bottom where you just line the bottom of the hole with smalls so water drains.

You don't have to splice. The wire can just pass through.

I've never seen HDPE electrical conduit in use or even for sale. Is it threaded? If so then IMO threading together is just as much work as gluing.
How long is the run that this is even a consideration?

It will be between 400 and 550 feet depending on the route I use. The shorter route goes through an area I might build on top of. I wasn't sure if the open bottom boxes could be used for power or not.


Is there a problem pulling the cable right off the reel? I figure I would rather get the stands and pull it right off the reel. I'm not sure if memory is going to cause problems that way or not. My understanding is I can order a reel with all 4 wires on it might pay a bit extra though. Do the wires that say they have the lube built into the jacket help or is it better to just use the lube? I will be renting a cable winch. When putting the warning tape in the trench with multiple items stacked do you just put the warning tape at the top or do you put warning tape above each type? I am going to have power, comm. and water in the same trench. Do I put warning tape at the top that says buried utilities or do I put one at the top that says buried comm. then below the conduit for the comm. put another one for buried electrical and below that one for buried water? I think I need a wider trench than I was thinking and will be able to offset them some.

 

[VHF]

It is residential. The problem is the run is too long for Ethernet over copper. I either go fiber or I have to put a repeater in somewhere. The reason for 12 count is I have a few other signals that don't like long distances and it is easier to convert them to fiber than Ethernet.

I've gotten away running 100BaseT over 400' before and it worked OK, although that does exceede the Ethernet specs. There are converters that will let you run networking signals longer distances over twisted pair. Some use mutiple pairs to increase bandwidth. At work we run about two miles using 4 dry pairs leased from the telco. This gives us a 22Mbit/sec connection to our remote building.

Of course, fiber has the advantage of not adding another another metalic path between buldings, so no worries with needing surge suppressors at the point of enty.

 

[ishiboo]

It most certainly is. I guess I should have been more specific with regards to the main two types of innerducts (there are more); smooth wall and corrugated. Yes, both are HDPE, and both are innerduct.

No, innerduct is cable management within a larger pathway/conduit/etc... it's the very definition of the word. Bury one alone and it's not innerduct There is even cloth innerduct for separating cables. Some people generalize and use the term "innerduct" when its not. For example, innerduct.com sells their HDPE conduit under their "Innerduct" brand but then proceeds to explain the applications:

Applications
Innerduct — Multiple lengths in sizes usually 1-1/4" and smaller pulled parallel into a larger conduit to divide it into multiple conduits.
Direct Buried — Burying one or more conduit lengths directly in the ground as pathways for future cable installation. Installation methods include open cut trench, pull or chute plowing, directional boring and pipe bursting.

 

[Aceman]

HDPE, is also available as CableCon. The wires are already installed in the conduit. We use it, but just for long runs to irrigation pivots. In your case, just use pvc. HDPE/CableCon is special order.

Here's a pic of a 4000' reel, the day I broke the farmers trailer spindle:

 

[ishiboo]

HDPE, is also available as CableCon. The wires are already installed in the conduit. We use it, but just for long runs to irrigation pivots. In your case, just use pvc. HDPE/CableCon is special order.][/URL]

You have a vibratory plow but not a spool trailer, Mr. Poopfarmer?

 

[VHF]

When putting the warning tape in the trench with multiple items stacked do you just put the warning tape at the top or do you put warning tape above each type?

Only the electrical requires a warning tape. Not sure of the exact code requirements, but I think it is generally installed half way between the ground surface and the buried lines. Hopefully anyone digging will hit the tape and stop before hitting the lines.

You may want a tape above your communcations lines as well, but in that case the tape is just to protect the lines. For burried electrical feeds the tape is to protect both the lines and the person doing the digging!

Make sure to use a proper red "burried wires" tape, not generic yellow "caution" tape. A backhoe operator won't stop when they see yellow tape--they'll assume it was a fragment of tape that had been used to cordon off an open excavation that just got burried when the trench was filled in.

 

[Aceman]

You have a vibratory plow but not a spool trailer, Mr. Poopfarmer?

We don't use a vibratory plow. We have a large spool rack for our trailer, but it's not big enough to handle an 8'+ spool.

They dig a 4'+ deep ditch out to the center pivot. They lay their water line and then we drag the Cablecon in beside it.

 

[lbmcse]

Every conduit run and resultant wire pull is unique. As others have said; your pipe should be completely glued and in place before wire pulling starts. Good idea on IMC 90s, as rope likes to bore through PVC 90s on tough pulls--which yours is sure to be. You could pull directly off the spools, but you'll have to have an a$$ ton of men present to pull this off (no pun). Sometimes it's best to have the reels at one end, sometimes it's best to have the reels in the middle of the run. The latter will necessitate pulling one half, then pulling the wire off the reels in preparation for the second half. Either way it's done, like said above, have guys feeding and lubing the hell out of the wire the whole time. It's a back saver. And ideally, use the "sim-pull" (slick jacketed wire) WITH pulling lube for best results. Don't expect to get away with "pre lubricated" conductors, without using wire lube too.

Open bottom boxes (sometimes called Brooks boxes) are acceptable. Make sure you insert bell ends on the conduit where they penetrate the boxes. It's required, and will save the insulation on the wires.

The question about passing through vs. splicing is up to you. Your job will require that before 360 degrees, a pull point (Brooks box) is in place. At that pull point you'll have to pull the entire run out, then continue from this point to the end, or to the next pull point. The preference is to pass through without splicing, but there's no restriction against splices.

Do yourself a favor and speak to the inspector first. He will tell you how he wants it done, and if you follow that to a T, you'll have no issues.

Lastly, HDPE is pretty specialized and spendy. If you use it, you won't be doing the job yourself, as it requires a directional bore. If money is no object, this would be the way to go, and a contractor would be performing the work. HDPE is not laid into trenches. As already said, it's like a slinky. PVC is a bit more work, but with proper planning and wise use of your resources, you'll be OK.

HTH. Good luck.

 

[kaffine]

You could pull directly off the spools, but you'll have to have an a$$ ton of men present to pull this off (no pun).

You make it sound as if pulling off the reel is going to be harder. I would have thought it would be easier to come off the reel. I haven't worked with cables this large though. I figure have the reel on stands above the conduit opening, use a guide on the conduit to make sure the cable doesn't get cut on the conduit. Then I need 2 people at the reel end 1 putting lube on the cable and the other watching the reel and cable to make sure it doesn't hang up. Have the person watching the reel have one of the switches for the puller so if there is a problem he can stop it. Or am I being really naive and it is going to be a lot harder than I think. I haven't been part of a cable pull with conductors this large or runs this long before nor have I used a power puller before.

If I lay the cable out on the ground first then I would have to have a lot of people to hold the cable up so it isn't being dragged across the ground. At least I assume I am not supposed to let it drag across the ground.

 

[lbmcse]

No, you've got it right. There's no reason to take the wire off the spools for pulling. As you said, though--it's important to have men manning the wire as it goes into the conduit to preserve the insulation. Wire dragging on the ground is not a bad thing as long as there's a man lubing the wire as it enters the conduit.

The only reason you'd remove the wire from the reels is if you start your pull from the middle of the run. Each scenario is unique, and sometimes this is the best way.

 

[wyliesdiesels]

Since no one else brought this up, I figure I would.

Im not sure what your feeding with this #2 al(all u metioned was residential), but if u plan on running a high amp load on it, voltage drop WILL be an issue. At your shortest length, 400' and 50a load, youre already looking at a 5.3% drop. At 550' and the same 50a, youre upto 7.3%.

Have u considered this and just what equipment will be used on this service?

 

[kaffine]

Since no one else brought this up, I figure I would.

Im not sure what your feeding with this #2 al(all u metioned was residential), but if u plan on running a high amp load on it, voltage drop WILL be an issue. At your shortest length, 400' and 50a load, youre already looking at a 5.3% drop. At 550' and the same 50a, youre upto 7.3%.

Have u considered this and just what equipment will be used on this service?

I took voltage drop into consideration. The normal load will be less than 2 amps however I wanted the ability to run power tools from that circuit. I could get away with running 10awg copper just not be able to use it to run power tools. However with the cost difference between 2awg aluminum and 10awg copper I would rather have the capability to run power tools if needed.

 

[lbmcse]

Wyliedeisels brought up a great point. Keep in mind that as voltage drops, amperage increases, as does heat, and potential for insulation degradation to conductors and windings to motors of tools. To avoid voltage drop concerns, you can consider derating the conductors to larger wire.

If the possibility exists that you'll ever be using this structure for a typical shop with multiple tools running simultaneously; you might consider addressing this before rather than after.

As they say when buying the better tool--cry once.

 

[wyliesdiesels]

I took voltage drop into consideration. The normal load will be less than 2 amps however I wanted the ability to run power tools from that circuit. I could get away with running 10awg copper just not be able to use it to run power tools. However with the cost difference between 2awg aluminum and 10awg copper I would rather have the capability to run power tools if needed.

Ok, I remember now. U had another thread....

Wyliedeisels brought up a great point. Keep in mind that as voltage drops, amperage increases, as does heat, and potential for insulation degradation to conductors and windings to motors of tools. To avoid voltage drop concerns, you can consider derating the conductors to larger wire.

If the possibility exists that you'll ever be using this structure for a typical shop with multiple tools running simultaneously; you might consider addressing this before rather than after.

As they say when buying the better tool--cry once.

Derating a conductor means lowering its ampacity, not increasing its gauge...

 

[lbmcse]

. . . .Derating a conductor means lowering its ampacity, not increasing its gauge...

You are correct. Backwards in my mind. My intent was stated, though. To compensate for voltage drop; larger conductors should be considered.