Results 1 to 7 of 7

Thread: distance between overhead and power pole

  1. #1
    Join Date
    May 2013
    Location
    Tujunga, CA
    Posts
    432

    distance between overhead and power pole

    Hi
    the utility company (LADWP) says ;
    the distance between residential overhead service drop and
    serving power pole that has transformer on shall be at least 35 feet

    Maybe, to achieve a under-10KA fault current?????

  2. #2
    Join Date
    Apr 2009
    Location
    Williamsburg, VA
    Posts
    5,438
    My guess is that it's so they have room to get to their transformers.
    Electricians do it until it Hertz!

  3. #3
    Join Date
    Jan 2009
    Location
    3 Hr 2 Min from Winged Horses
    Posts
    14,196
    Maybe I am a bit confused.

    Where is this requirement?

    http://www.kallin.com/ParkDrive/DWPSection7.pdf
    "Electricity is really just organized lightning." George Carlin


    Derek

  4. #4
    Join Date
    Mar 2013
    Location
    Rutland, VT, USA
    Posts
    321
    There is nothing in the NESC that states that distance so this is a utility specific requirement. It may be to give their bucket trucks working clearance from adjacent structures.

  5. #5
    Join Date
    Dec 2007
    Location
    NE Nebraska
    Posts
    36,786
    Quote Originally Posted by Toros View Post
    Hi
    the utility company (LADWP) says ;
    the distance between residential overhead service drop and
    serving power pole that has transformer on shall be at least 35 feet

    Maybe, to achieve a under-10KA fault current?????
    You mean distance to the load end of the drop? The drop pretty much has to connect to the pole if not where are you going to get supply from?

    I have seen some service drops that are nearly straight down from the point of attachment on the pole, building is less then 5 feet from the pole.

  6. #6
    Join Date
    Apr 2009
    Location
    Williamsburg, VA
    Posts
    5,438
    Quote Originally Posted by kwired View Post
    You mean distance to the load end of the drop? The drop pretty much has to connect to the pole if not where are you going to get supply from?

    I have seen some service drops that are nearly straight down from the point of attachment on the pole, building is less then 5 feet from the pole.
    Yeah it attaches to the pole, tho not every pole has a transformer.
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    As far as fault current below 10kA, I doubt that's it, most pole mounts would be 75kva or less and have to have an impedance of less than 3% to top 10kA available fault current, assuming an infinite primary. I dunno how much even 25' of 4/0 cable would further reduce the available fault current... I doubt the rule toros cited is to make it easier on residential electricians in selecting appropriate panels. I havent priced a panel with a 22kVA AIC lately, afaik that's the next step up from 10k.
    Electricians do it until it Hertz!

  7. #7
    Join Date
    Dec 2007
    Location
    NE Nebraska
    Posts
    36,786
    Quote Originally Posted by JFletcher View Post
    Yeah it attaches to the pole, tho not every pole has a transformer.
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    As far as fault current below 10kA, I doubt that's it, most pole mounts would be 75kva or less and have to have an impedance of less than 3% to top 10kA available fault current, assuming an infinite primary. I dunno how much even 25' of 4/0 cable would further reduce the available fault current... I doubt the rule toros cited is to make it easier on residential electricians in selecting appropriate panels. I havent priced a panel with a 22kVA AIC lately, afaik that's the next step up from 10k.
    Most loadcenters have 22kA main breakers installed and are series rated for use with 10kA breakers. I mostly use Square D loadcenters, but I would guess the others sort of do about the same thing.

    25 feet of just about any size conductor does make a significant difference in reducing available fault current on most any single phase source I have ever come across.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •