a wire snoodling issue....

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Fulthrotl

~Autocorrect is My Worst Enema.~
i've got a bit of a dilemma, and i'm wondering if anyone has had a similar experience.

here's what i have in front of me:

4" PVC underground, 150' long, beginning and ending at a concrete soil box.
24" radius 90 on each end, with a bell mouth on it.
four #3/0 aluminum conductors in the pipe, with a piece of mule tape
as a drag line for future additions.

what needs to be added to the pipe:
four #250 mcm simpull aluminum conductors.

the mule tape was added after the original pull, with a duct rod,
so it's a straight shot and not twisted, laying on top of the existing
feeders.

now, the rub. the existing feeders are hot, and can't be turned off.
i'm looking at putting a choker on the existing wires and tying it off,
to keep them from being moved in the pipe, dumping a gallon or two
of polywater down the pipe, and pulling the conductors in by hand,
so i can feel if anything is sticking.

anyone got experience with doing this, good or bad? snoodle one wire
in at a time, using the mule tape with timber hitches as a drag line?
or make up a padded head with rags and tape, to make it slide better,
and do it with all four at once?

thanks for any experience....
 

GoldDigger

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Not having tried it myself I would worry about the trade off of the lower pulling force one at a time against the greater chance of one jamming in the groove left by an earlier pull.
I realize that is more of a risk with a bend than with a straight pull....
 
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ActionDave

Chief Moderator
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Location
Durango, CO, 10 h 20 min from the winged horses.
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Licensed Electrician
anyone got experience with doing this, good or bad? snoodle one wire
in at a time, using the mule tape with timber hitches as a drag line?
or make up a padded head with rags and tape, to make it slide better,
and do it with all four at once?

thanks for any experience....
One at a time seems to make sense for getting around the bends. I'd be afraid that no matter how nice the mule tape was introduced into the conduit it's going to want to wrap itself around the the existing conductors or slide between them once the pulling tension hits.....if not on the first run then on the second or third.
Strike one against pulling one at a time.

You have a hundred and fifty foot pull, that's not bad. One at a time turns it into a six hundred foot pull and the pipe getting more crowded each go round.
Strike two.

Four 250MCM's hitting the second ninety with wires already in the pipe......ughh. I don't like that either. I'm thinking a long stagger, say three or four feet on each of the 250's would make it possible to pull all four at once without all of them having to make the second bend at the same time.

No padded head with rags and tape. I've never done it but it sounds like adding something that could get in the way more than it could help.

I'm getting old, I'd use a tugger. With only two wraps on the mule you could still feel if something got jammed and let go fast enough.

Are you doing this lone eagle style?
 

Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
I agree with Dave. I'd do it all at once.

I'd also want to meg the existing feeder after the pull to verify there are no issues either. You'll look like a hero keeping the other feeder hot during the pull, but you'll wipe all those atta boys away if something were to happen a short while down the road...
 

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
I agree with Dave. I'd do it all at once.

I'd also want to meg the existing feeder after the pull to verify there are no issues either. You'll look like a hero keeping the other feeder hot during the pull, but you'll wipe all those atta boys away if something were to happen a short while down the road...

How would you do that?

ice
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
I agree with Dave. I'd do it all at once.

I'd also want to meg the existing feeder after the pull to verify there are no issues either. You'll look like a hero keeping the other feeder hot during the pull, but you'll wipe all those atta boys away if something were to happen a short while down the road...

If the existing feeder can be turned off to be megged, why not when it's being pulled over?
 

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
...now, the rub. the existing feeders are hot, and can't be turned off. ....
Curious why can't the existing feeder be turned off?
...Four 250MCM's hitting the second ninety with wires already in the pipe......ughh. I don't like that either. ?

Yes, Why it can't be turned off could matter.
If the issue is: "We have 10 people on iron lungs and we never bothered to put in emergency power sources.
Or, "It costs us $500K to shutdown for a day"
Or, "Well, it is inconvenient. We have to send every one home and give them a days pay."

If iron lung issue, I'd be telling them to dig a new ditch.

If a lot of money, I'd be saying, "We have arisk of tearing the existing conductors in two- not a lot of risk, but it is there. We have done this successfully before, but we have also have had to stop because we could not hold the existing from moving. We have not ever damaged an existing, but there is a risk."

If inconvenience, try, "We can do it at night - minimal impact. Pull the old out, pull in all new. Existing is up and running before morning."

And if the response is, "We will take the risk." Get pulling.

All the pulls over existing I have done were small conductors. So I expect my opinion on this is not an informed one. However, I like the long staggered tails, small knot, beat all the sharp ends down and tape - maybe even a wrap of fiberglass tape. Vinyl tape is sticky - especially on pvc

ice

Just an opinion
 

Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
How would you do that?

ice

If the existing feeder can be turned off to be megged, why not when it's being pulled over?

That's what I'm saying. It doesn't seem worth it to me to pull it in next to live conductors, which is a huge pain, plus you wouldn't be able to meg it after the fact.

If the customer is so worried about keeping the existing feeder online why wouldn't they want to schedule a shutdown to pull the wire in and then test the insulation integrity after the pull? Sounds like a catch 22 to me.

Fortunately, I've always been able to schedule a shutdown. Sometimes there is some resistance to the idea, but usually after they think about it, they realize they can do some other maintenance they've been putting off for a while at the same time and then it's not such a problem.
 

Fulthrotl

~Autocorrect is My Worst Enema.~
That's what I'm saying. It doesn't seem worth it to me to pull it in next to live conductors, which is a huge pain, plus you wouldn't be able to meg it after the fact.

If the customer is so worried about keeping the existing feeder online why wouldn't they want to schedule a shutdown to pull the wire in and then test the insulation integrity after the pull? Sounds like a catch 22 to me.

Fortunately, I've always been able to schedule a shutdown. Sometimes there is some resistance to the idea, but usually after they think about it, they realize they can do some other maintenance they've been putting off for a while at the same time and then it's not such a problem.


well, it turns out, the existing pipe was completely full of water.... so we have
reasonable expectations that the insulation is acceptable, and after we have
pulled the new feeders in, the expectation is that their isn't steam coming out
of the pipe, so the feeders are still ok, or ok enough.

it's a changeover. a 200 amp panel is being refed from a different location,
converting it from a separate service, to a subpanel on a new service i installed
last year. the pipe in question goes from a ground box near a pole, to a ground box
next to a building, with splices in both boxes. the existing wires that can't be turned
off are service entrance conductors, coming off the pole. xfmr on the pole has primary
fuses only, and with the loads on the secondary, is fused high enough to burn a while
in a short circuit situation.

hence the caution on my part. i'd rather be cautious and not need to be, than find
out i was suffering from a caution deficiency disorder halfway thru the job, when
your days work gets elevated to "film at 11" status.

put timber hitches and about ten half hitches on the wire over about two feet,
completely covered the hitches with a roll of scotch 33, poured two gallons of
poly water in the pipe, and pulled it by hand... had a guy feeding, and it went
so easily i pulled it one handed. kinda embarrassing after excessive fussing with it.

i'll set the transformer tomorrow, and see if i can cut everything in tomorrow
night, removing the poco service feeders back to the pole, and closing everything up.

pulling 480 volt feeders in a service conduit with 240 delta service, you ask?
well, yeah. the POCO scheduler, and the HV splicer who's gonna cut the job in
next week and i had a meeting, and worked out how it's gonna look, and what's
gonna happen..

it's ok. i got a note from mommy that says so. honest.

thanks for all the feedback. i appreciate it.
 

ActionDave

Chief Moderator
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Location
Durango, CO, 10 h 20 min from the winged horses.
Occupation
Licensed Electrician
put timber hitches and about ten half hitches on the wire over about two feet,
completely covered the hitches with a roll of scotch 33, poured two gallons of
poly water in the pipe, and pulled it by hand... had a guy feeding, and it went
so easily i pulled it one handed. kinda embarrassing after excessive fussing with it........
You are a madman. How do you do it and still find any thrill left when riding motorcycles?
 

electricalist

Senior Member
Location
dallas tx
I'd use it to see how the wires are laying in the turns and get some measurements laid out in case something gets caught up .
Just trying to helpfully.
 

Jon456

Senior Member
Location
Colorado
I'd use it to see how the wires are laying in the turns and get some measurements laid out in case something gets caught up .
Just trying to helpfully.
I understand and was not trying to be critical of your assistance. I'm just relaying my experience with videoing buried conduit.

We had a 4" PVC conduit, 185' in length, that contained 500 MCM aluminum feeders (480V 3-phase, 1,200A OCPD); those feeders had a direct phase-to-phase short.

After pulling out all the wire, we ran a video camera through the conduit to try to determine if the arc blast damaged the raceway. We swabbed it first and put a tube in the conduit to try to pump out as much water as possible. But still there were a number of low spots that contained pockets of water that filled the conduit. Each time the camera head entered a pocket of water, we lost all visibility: all we could see was a blurry image of murky water.

The OP stated that his entire conduit was filled with water, so....

Additionally, it would probably be impossible to push a camera through a conduit that contained wires. If you put a mule tape on the video head to pull it from the other end, then most of the camera's view would probably be obscured by the mule tape.
 

rt66electric

Senior Member
Location
Oklahoma
can you bore a new line , or dig a new ditch??

can you bore a new line , or dig a new ditch??

can you bore a new line , or dig a new ditch??

Hook-up a temporary generator, then pull out old stuff, then add new conductors and pull all in again???
Pulling new wire with hot old wires, seems risky....

might try it once, then, give up , before the new starts tugging the old and KABLUEEE..
 

electricalist

Senior Member
Location
dallas tx
I'm not a walking hazard and not the guy who gets almost nothing done for any and every possible safety issue.
As risky as this install sounds I wouldn't attempt it. Not because I'd be scared , more because it's not logical to determine that it must be done. Shutting down us too critical we didn't have a plan for a problem when it's SOOOimportant to keep running..
 
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