Announcement

Collapse
No announcement yet.

.8 rule

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • .8 rule

    Originally posted 10-02-2018 7:39 AM

    I received this email and replied with the link to this post...

    This was received by email...

    EMT FILL QUESTION

    I am studying for exam and ran across this. Does the .8 rule pertain to this application? Thank you for your time!

    4. Find the size EMT nipple required to enclose 3 each 500 kcmil THHN conductors between two panels

    a) 1 1/2 inch

    b) 2 inch

    c) 3 inch

    d) 3 1/2 inch

    ## CORRECT --> The area for 3 -500 kcmil THHN conductors is 3 x .7073 = 2.1219 For 60 percent fill using the .8 round off method requires a 2 inch EMT.

    Bob

  • #2
    Originally posted 10-02-2018 1:56 PM

    Sort of. You take the 60% conduit fill area of 2" EMT which is 2.103 inches and divide that by .7073 (the area of one conductor). That comes to 2.97 conductors allowed. If the result was 2.8 or greater, you'd be allowed to round up to 3 conductors in that conduit using the .8 round up rule. The question should have also stated that the nipple was 24" or less in length so you know you can use 60% fill instead of 40%.

    So what you're supposed to be rounding up is conductor count, not area required.
    Mark
    Mark
    Kent, WA

    Comment

    Working...
    X