Duct Bank/Manhole Pull Process

[Alwayslearningelec]

Can someone explain the sequence of events to pull 2 sets of 4 #500 through underground duct bank. It's a total of about 800' with 3 manholes in between.

Thanks.

 

[don_resqcapt19]

There are just way too many possible combinations to come up with a pulling plan with out actually seeing the layout. One of the first things I would look at is to see if it would be possible to pull straight through at least one of the manholes. The labor and risk of conductor damage both go up significantly where you have to feed into a manhole and then spool off the rest of the wire and feed it back in that manhole to finish the pull.

 

[infinity]

If this is 600 volt cable It's either a straight pull all of the way or a splice in the middle.

 

[petersonra]

If this is 600 volt cable It's either a straight pull all of the way or a splice in the middle.

That would seem to be the choices.

A long time ago in a galaxy far, far away, I was on a job site where the utility installed some kind of huge electric cable inside a storm sewer. Never saw that before. I think they went in after it was pulled and secured it to the top of tunnel. I am pretty sure there were alligators down there. I would not want to be the guy working in the storm sewer.

 

[Alwayslearningelec]

There are just way too many possible combinations to come up with a pulling plan with out actually seeing the layout. One of the first things I would look at is to see if it would be possible to pull straight through at least one of the manholes. The labor and risk of conductor damage both go up significantly where you have to feed into a manhole and then spool off the rest of the wire and feed it back in that manhole to finish the pull.

Good info about pulling straight through. The labor goes up when you can't pull through because of the setup involved with the reels?

 

[don_resqcapt19]

Good info about pulling straight through. The labor goes up when you can't pull through because of the setup involved with the reels?

And the fact that you have to spool off the other end, and stretch it out or figure 8 it and then pull that end in. It takes more labor to feed cable that way than when you are feeding it off the spools. You also have to relocate your pulling equipment.
With the right equipment, you can even rig sheaves in a manhole to pull around corners, but make sure you have large radius wheels and the sidewall pressure may be high enough to crush the insulation with a small diameter wheel.
You would need to run a pulling combination to look at the required pulling force and the sidewall pressure issue.

 

[Alwayslearningelec]

Why would you be spooling off the wire? If your not splicing in the manhole there would be no reason to not to pull through.
There could be an instance where you would pull in/out of each manhole if you weren't splicing?

 

[don_resqcapt19]

Why would you be spooling off the wire? If your not splicing in the manhole there would be no reason to not to pull through.
There could be an instance where you would pull in/out of each manhole if you weren't splicing?

If I am not doing a straight through pull, the reels would likely be set up at the middle manhole, and the conductors pulled to one end, then the wire would be spooled off and fed in the other direction. However each case is different, and the pull layout would be set up by the electricians doing the pull. There may be cases where you would feed in the first manhole, pull the conductors out at the second manhole, and then feed them back in to pull to the third.

As far as pulling thought or not, it depends on the duct configuration in the manholes, that is straight or 90s, the pulling equipment you have available and the results of the wire pulling calculation. The most common mistake is that the pulling sheaves for a 90° pull have a diameter that is too small resulting in excessive sidewall pressure and possible damage to the conductor insulation.