ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Top Posters(30 Days)
twh 3
Recent Posts
FPE in Germany
by Texas_Ranger. 11/19/17 07:30 AM
Ceiling fan distance from outdoor hot tub
by gfretwell. 11/16/17 02:18 AM
diazed fuses
by Texas_Ranger. 11/13/17 03:02 PM
Theft deterrent alarm
by gfretwell. 11/12/17 01:39 PM
EEPROM errors on XC7Z010-2CLG225I chip
by twh. 11/07/17 05:45 PM
New in the Gallery:
Gallery Test
Popular Topics(Views)
242,610 Are you busy
178,797 Re: Forum
170,043 Need opinion
Who's Online Now
2 registered members (crselectric, tomn), 46 guests, and 9 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate This Thread
#205568 - 03/09/12 04:18 PM mca and mocp nameplate  
Bravo  Offline
Member
Joined: May 2010
Posts: 30
NY, USA
Hi have a chiller rated 208V, 3P, MCA: 46.1, MOPD: 80, RLA: 30. Its been awhile for sizing motor branch ckts but any idea how to size the ckt. & OCPD?

Correct me if I am wrong but last I remember based on the nameplate info conductors can be #6 with 60A circuit breaker?
MCA = minimum current ampacity
OCPD = maximum over current protection device

Where in the NEC doesnt reference sizing ckts per nameplate?

thanks in advance


2017 / 2014 NEC & Related Books and Study Guides

#205569 - 03/09/12 04:43 PM Re: mca and mocp nameplate [Re: Bravo]  
electure  Offline


Member
Joined: Dec 2000
Posts: 4,262
Fullerton, CA USA
NEC Article 440 is the one you want to read for this.

You can use #8 for a MCA of 46.1, with up to an 80 amp hacr breaker or fuses for the MOPD.


#205570 - 03/09/12 04:49 PM Re: mca and mocp nameplate [Re: electure]  
Bravo  Offline
Member
Joined: May 2010
Posts: 30
NY, USA
#8 is good for 40A in the 60deg C column of table 310.16. I think I need to use this for equipment rated 100A or less?


#205571 - 03/09/12 10:53 PM Re: mca and mocp nameplate [Re: Bravo]  
George Little  Offline
Member
Joined: Jan 2004
Posts: 1,489
Michigan USA
Make sure the terminals in the Chiller are rated for 75 C if you plan on using #8 copper wire. Most equipment of this nature are only rated for 60 C and that would call for a #6. As for the line side of the disconnect (assume it is separate from the Chiller) it probably would be rated 75 and #8 would be fine. The 80a. overcurrent device is proper in either case.


George Little


Member Spotlight
BEAMEUP
BEAMEUP
WA
Posts: 27
Joined: December 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: 0.011s Queries: 15 (0.002s) Memory: 0.7598 MB (Peak: 0.8928 MB) Zlib enabled. Server Time: 2017-11-21 23:01:06 UTC