distance between overhead and power pole

[Toros]

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?????

 

[JFletcher]

My guess is that it's so they have room to get to their transformers.

 

[jumper]

Maybe I am a bit confused.

Where is this requirement?

http://www.kallin.com/ParkDrive/DWPSection7.pdf

 

[wbdvt]

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.

 

[kwired]

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.

 

[JFletcher]

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.

 

[kwired]

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.