ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Grounding electrodes
by gfretwell - 09/07/21 03:41 PM
Looking For Electricians in the Midlands
by Alex247 - 09/06/21 05:26 AM
Backup Generator Done Right
by timmp - 08/31/21 04:44 PM
New in the Gallery:
Now you know.
Now you know.
by Tom_Horne, September 7
February, North East Indiana
February, North East Indiana
by timmp, July 25
Who's Online Now
0 members (), 39 guests, and 19 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Joined: Jun 2007
Posts: 19
S
site351 Offline OP
Member

Got a question and don't have a code book....

A 3" P.V.C.conduit is ran from under ground transformers
to electric meter packs with 150 breakers. All meter packs
are main lug, no main breaker. Some meter packs contain six
meters and some five, some four. 120/240 volt residential.
I know I can parallel the Pratt 250-250-4/0 alu. in a 3"
p.v.c. pipe...is that big enough to handle the load for
the five and six meter packs ?
6x 150= 900 total amps for the six banger @ 45% = 405
amps ? can't remember how much to derate...
Five meter pack may work with 250...just not sure about the six ... thanks....

2017 / 2014 NEC & Related Books and Study Guides
Joined: Dec 2002
Posts: 317
S
Member
Assuming that you have done calculations on the services and have found that they all are at 150 amps. 5 residential services can be calculated at .45 for a total of 337.5 amps (see 220.84).

6 residential services can be calculated at .44 for a total of 396 amps. Same code reference. Parallel conductor installation of 250 kcmil are good for the 400 amp total (255x2x.8 NEC 310.15(B)(2)(a)) if allowed by your AHJ.

I did not check the nuetral. This also makes the assumption that you meet the multi-residential requirements.


Link Copied to Clipboard
Featured:

Tools for Electricians
Tools for Electricians
 

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
electure
electure
Fullerton, CA USA
Posts: 4,287
Joined: December 2000
Top Posters(30 Days)
timmp 3
Popular Topics(Views)
282,928 Are you busy
216,696 Re: Forum
203,120 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.5