Replies

1. 
   UncleDunc | Dec 25, 2003 12:42am | #1

   >> 3. Any ideas on the best conduits to use, running extras, or making a better job?

   I saw a conduit job going in on a university campus once. It was nine separate 4" PVC tubes stacked three high by three across, mounted on racks every few feet to hold the tubes in position, and then the whole thing encapsulated in concrete. A little elaborate for one house, but you'd have to be going plumb hog wild with a big backhoe to cut any of those cables by accident.

   I'd probably put in a bigger conduit instead extra smaller ones, but I'm not sure I could justify that preference.

2. 
   MikeR | Dec 25, 2003 01:41am | #2

   On all the jobs I've done, I've run 2" PVC conduit for the electric and than a 2" for the cabletelephoneCat 5 in the same trench with no interference problem whatsoever.  These were all residential projects however, not a high use commercial applications.

   They make industrial conduit that is either grouped and color coded for usage (say four runs in one module) and I think I've even seen shielded conduit but you're talking big bucks.

   If its residential, I'd say as long as you keep the voltage lines separate from the communication lines (i.e. different conduits) you'll be OK.  As long as of course the AC lines are not more than 220v.

   Mike

3. 
   Lateapex911 | Dec 25, 2003 03:07am | #3

   Always in seperate conduits! Common sense, code, and all that.

   I always requested a foot seperation between high and low voltage when running parallel over any distance. Closer is fine if at a sharp angle.

   Jake Gulick

   [email protected]

   CarriageHouse Design

   Black Rock, CT

4. 
   fireball | Dec 25, 2003 06:39am | #4

    You should probably call your utility companies first and ask about their requirements.If these are service conduits to a home they might insist that only they can put them in,or that you can install the conduit to their specs but they have to pull the wire.Find out first if they'll allow the conduits together.If the phone company is responsible for maintaining your underground service,and something happens to it,they don't want to dig up the electrical conduit while trying to fix their stuff.That's more of a reason for separation than possible interference.

   If you do install the conduit use schedule 40 underground and schedule 80 aboveground.Some people like to use galvanized steel 90's because during the wire pull the rope can cut into the inside radius of a plastic 90.Follow the minimum depth requirements for your situation.If the electrical conduit is your service most inspectors want to see it before being covered up,and you have to have a warning ribbon above it.

   A good trench has the conduits covered over with pea gravel or sand.That way goonies can't smash your pipe during backfilling,and if anybody ever digs near it again they'll recognize the soil difference and proceed with more caution.

1. 
   DaveRicheson | Dec 25, 2003 07:51pm | #7

   Sweeping ells have to be schedule 80 or galvanized here. Good idea, those ells take a lot of pressure on long pulls.

   Dave

5. 
   Mongo | Dec 25, 2003 09:14am | #5

   They can go in the same trench.

   However, have the trench dug with a 24" or 30" backhoe. Put electrical on one side, the other conduit (phone, cable, extra) on the other side. Having the electrical 18" from the others is adequate to minimize interference.

   In my area, the local utility specs out 4" Sch 40 for the electrical, but they will let you run 3" if you ask.

   Usually it's 3" on one side for electrical, and two 2" conduits on the other. One for phone, one for cable or future use.

   Watch the overall elevation change between the street end of the conduit and the house end of the conduit. If the house is lower than the street, it could act as a water main and bring water to the house. Someone had a thread going titled something like "meter box water fountain" detailing this problem.

   Some installers like to set the pull rope as they lay the pipe. Some like to run the entire pipe then pull a string through the conduit with a vacuum, then use the string to place a pull rope. Different strokes.

   Watch the bends as Barry wrote.

   If you have a long pull, or too many bends, you may need an intermediate pull box to break a long pull into two or more shorter pulls. Your utility can give you guidance on that.

   Call your utlity for guidance. It'd be a shame for you to lay conduit according to what we said, only to have them tell you they're not going to pull the service through it.

   If I recall, I think our utility also had something about the electrical service being the only service to be allowed in the trench. However, though it's not written anywhere, they also consider "being the only service in the tench" to mean "no other services within 18" of the electrical". Thus, the wider trench (24" or 30") gets you by on that one by llowing you to space the other runs at least 18" from the electrical.

6. 
   greggo | Dec 25, 2003 10:10am | #6

   I'm the guy who had the meter socket water fountain.Like Mongo said,be careful of a long run sloping down,

   In CT you can run the lines in the same trench but in  different conduit,they must also be spaced about 18" apart  X amount of feet deep

   One thing I should have done was use 20' instead of 10',at least for the 2" lines You can do it on the larger lines if you got help

   I installed the pull line after the pipe was laid.

   the first pull in 3"  was about 450" straight run. I got a DWV adapter and connected it to a shop vac at one end of the run. on the other end ,I used an old  deep sea rod and fishing reel loaded up with 60 lb test line leading off with a foam mouse. turned on the vac,drove down to the other end,stuck in the rod and the BIG Tuna took off.

   For some reason the 2" lines took a couple of tries before the mouse  went thru

   Also if you use the vac for your lines,try blowing them first to get the crud out of the lines so the mouse can slide easier

   stay safe Greg

7. 
   CJD | Dec 27, 2003 06:43pm | #8

   Is it a good idea to put in drain pipe to keep the water level in the trench low?

1. 
   greggo | Jan 01, 2004 12:35am | #9

   Not sure about in the trench but, if I did mine again I would definitely put a piece of 3" pipe in the handhold run out to daylight.And if you are slopping down hill to the meter socket I think maybe the last 10' before the M/S I would drill some holes in the conduit for drainage.

1. 
   brownbagg | Jan 01, 2004 01:24am | #10

   i got my main power entrance and my cable modem in the same trench, no problem so far.

   The best employee you can have but you wouldn't want him as a neighbor " He the shifty type"

8. 
   CJD | Jan 06, 2004 07:40pm | #11

   I just came across another idea that makes sense. Place rebar or scrap metal pipe on top of yellow warning tape 6-8" above the conduit or pipe what backfilling. Someone may go through the tape without noticing but are not likely to miss rebar.