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Thread: MV Pulls

  1. #1
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    MV Pulls

    We are going to talk about this internally but I’d like to have some talking points to bring up regarding pulling and setup. Not expected but it would be nice if I could. This is not usual bid work I come across but I think there should be some serious thought given to the pulls etc.. Most of the duct banks consist of EXISTING 4” PVC. There on average (9) conduits in each duct bank. Average run is about 800’ and going through We are pulling 3 #500 5kv cables plus 600v ground in each conduit. I’m thinking:

    Setup- I guess the wire will be delivered and staged somewhere on site. How are we getting it from staged area to where the pull will take place?
    What is the most efficient way to do these pulls?
    What will our pull points be?
    Setup and Breakdown times?

    Thanks guys.
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  2. #2
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    Temperatures on pulling days.

  3. #3
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    What is a 600V ground?

    If insulation, why can the ground/EGC have a lesser value given 300.3(B)?
    "Electricity is really just organized lightning." George Carlin


    Derek

  4. #4
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    When was a mandrel pulled through last?
    What if it doesn't pull through?
    How many elbows are there?
    Who is doing the pull calculations?
    Are there conductors in there currently?
    Is there a need to verify the ductbank configuration / depth to reconfirm Neher McGrath calculations?
    Ron

  5. #5
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    Quote Originally Posted by jumper View Post
    What is a 600V ground?

    If insulation, why can the ground/EGC have a lesser value given 300.3(B)?
    See 250.184 A 1

  6. #6
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    Quote Originally Posted by ron View Post
    When was a mandrel pulled through last? We have to mandrel.
    What if it doesn't pull through? Will mandrel? If mandrel doesnt go through I don;t know what happens.
    How many elbows are there? About 3 in each run with manhole that 90's the run.
    Who is doing the pull calculations? OUr engineer after we get job.
    Are there conductors in there currently? No
    Is there a need to verify the ductbank configuration / depth to reconfirm Neher McGrath calculations?
    .

    When was a mandrel pulled through last? We have to mandrel.
    What if it doesn't pull through? Will mandrel? If mandrel doesnt go through I don;t know what happens.
    How many elbows are there? About 3 in each run with manhole that 90's the run.
    Are there conductors in there currently? No
    Is there a need to verify the ductbank configuration / depth to reconfirm Neher McGrath calculations. Not sure what you mean.
    Thanks!!!

  7. #7
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    Quote Originally Posted by jumper View Post
    What is a 600V ground?

    If insulation, why can the ground/EGC have a lesser value given 300.3(B)?

    Yes if we are pulling 5kv #500 there is a 600v #2/0 ground.

  8. #8
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    Quote Originally Posted by sameguy View Post
    Temperatures on pulling days.
    And how does cold( i'd imagine cold would negatively affect pull) affect pull?

  9. #9
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    Quote Originally Posted by mstrlucky74 View Post
    And how does cold( i'd imagine cold would negatively affect pull) affect pull?
    As it gets below 40°F the wire is much stiffer and harder to handle. Most conductor types cannot be handled below 14°F without risk of damage to the insulation.

    Someone will have to do the pulling calculations. With 3 90s in an 800 foot run, there is risk of exceeding the maximum permitted sidewall pressure. To find the sidewall pressure you need to find the pulling tension coming out of each 90, and also know the radius of the 90. The sidewall pressure and not the actual pulling tension, is most often the limiting factor in a pull.

    As far as pulling, for the above reason, it is always best to have the bends closer to the feed end, than to the pulling end. However you are limited by the installed configuration.
    Don, Illinois
    (All code citations are 2017 unless otherwise noted)

  10. #10
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    Quote Originally Posted by MyCleveland View Post
    See 250.184 A 1
    Thank you.
    "Electricity is really just organized lightning." George Carlin


    Derek

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