Earlier this week, I had to pull two #10s & a #12 EGC about 325 feet underground thru 3/4" PVC. Two 90s & a 45 bend in the run.
It was a bear for several reasons, but I would like to know how to do it better next time (my boss put the RMC in the grd, not me).
3/4" is plenty large enough for three wires, but does it get any easier for a long run if it had been 1.25 or 1.5" conduit? Does the drag matter that much in 3/4" pipe?
If you had this long of a run for two #10s & a 12 (all stranded), what size PVC would you install?
Thanks,
Rick
There was something else in that conduit, sand or something from being installed incorrectly. And if there are 90s any where else but where the conduit comes out of the slab then that's probably what gave you trouble.
If you pulled in a rope or fish tape with jet line you may have cut into one or more of the 90
If the man on the feeding end wasn't holding that wire so that it didnt get hung up on the lip of the TA or whatever he was feeding into, you really had a problem.
All I've been doing for a month is running a wire crew pulling into the conduit the crew and I put in the slab. 5-7 #10s in runs anywhere from 15 to 175 feet. Ad use lube.
On underground projects this size when possible,assemble the pipe 325' in two sections, pull the wire in two pulls,glue the sections when the wire is in and roll the whole thing in the trench.
With PVC Ill try and go two sizes up when doing long runs with multiple 90s. I learned this the hard way. Doing straight runs with your 3/4 is one thing but over 300ft with two 90s and a kick your setting yourself up for a hard pull.
Some guys have done similar runs and it can't be fished, even when fishing from both ends trying to hook the other fish, or Vacuum.
Just ran a 400ft run a month ago with over 3 90s, two #10s and bond, I used an 1 1/4.
On underground projects this size when possible,assemble the pipe 325' in two sections, pull the wire in two pulls,glue the sections when the wire is in and roll the whole thing in the trench.
I'm assuming you used a string to pull in the wires. My first thinking was that the head was made up poorly. Combine that with the string stretching and that would make a heck of a pull.
Use GRC sweeps on the ends of the runs you will be pulling from. If using PVC sweeps in smaller conduit sizes, bend your own sweeps with longer radiuses. If there is a PVC sweep burried at the end where you are pulling from, slide a piece of FMC inside of the conduit long enough to pass all the way through the sweep. Thread the pull rope through it prior to starting the pull. The flex will prevent the pull rope from slicing through the inside of the sweep during long pulls. We have these whips made up in our shop with various sizes of flex. One end of each one is terminated in either a blank plate or trough end to stop it from sliding down into the conduit end. When the pulling head hits the end of the flex, just let the head pull the flex up out of the conduit with it. We have used this method for runs up to 1000' long with all sizes of conduit and wire.
Also, we use 1" minimum for UG conduit runs, over 500' minimum 2", use pulling lube and double braid ropes. We also use the same flex to protect the PVC sweeps when drawing the ropes in with pull strings.
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