ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Top Posters(30 Days)
dsk 13
Admin 8
Recent Posts
OD of Alum and Copper
by gfretwell. 08/22/17 07:04 PM
Grid problem??
by annemarie1. 08/21/17 01:10 PM
Bathroom electrical
by doc. 08/19/17 06:53 AM
electircal ageing test on IPC
by SIAME. 08/15/17 02:43 AM
electrical aging test on IPC
by gfretwell. 08/15/17 12:27 AM
New in the Gallery:
Gallery Test
Popular Topics(Views)
240,107 Are you busy
175,723 Re: Forum
167,935 Need opinion
Who's Online Now
0 registered members (), 56 guests, and 7 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate This Thread
#102675 - 08/02/06 08:52 PM BX to motor...  
Cinner  Offline
Member
Joined: Dec 2004
Posts: 78
Kelowna, B.C., Canada
Is is right to pull a 12/3 BX wire to a 3 phase motor and use the white wire as the blue phase?

12/3 BX (red, white, black) is from a JB, which is pulled to from the panel in the right colors, to the motor, approx 8 Meters.


Tools for Electricians:

#102676 - 08/03/06 12:29 PM Re: BX to motor...  
mikesh  Offline
Member
Joined: Jun 2006
Posts: 613
Victoria, BC, Canada
You may use the white wire by making it unidentified. Paint or tabe it blue at every location the conductor is accessible.
Until the 2006 code is enacted without amendments to tables 16 and 17 you may have a problem with the bonding conductor size.

A motor conductor is sized to the FLA of the motor say it is 14 amps. The conductor size is 14 X 1.25 or 17.5 amps. A number 12 BX is OK for the motor but the potential overcurrent protection presents a challenge. If you used the max breaker size of 35 amps the bonding conductor is too small at #14. An ISO type of bx with a full sized #12 bonding conductor would take care of this. Alternately you would need a # 8 cable to meet the min #10 bonding conductor from table 16. So why can I use a #12 ISO bx and need a #8 if I use a regular BX. The bonding conductor never needs to be larger than the circuit conductor. The 2006 code sizes the bonding conductor to the wire size appropriate for the load not to the OC device protecting the load.
The cheapest solution now is ISO bx. Alternately an EMT run proximate to the motor with a short piece of flex and a #12 Bonding conductor in the flex works too. If the 2006 code is adopted without any amendments to table 16 and 17 then the #12 bx with taped or painted white wire works.



Member Spotlight
Theelectrikid
Theelectrikid
Levittown, PA
Posts: 810
Joined: April 2004
Show All Member Profiles 
Featured:

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Shout Box
Powered by UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.009s Queries: 14 (0.002s) Memory: 0.7441 MB (Peak: 0.8619 MB) Zlib enabled. Server Time: 2017-08-23 04:30:12 UTC