ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
Video door bell causing chime activation of coil
by crselectric. 12/16/18 02:12 PM
Our Company!
by faradaygroup. 12/15/18 09:23 PM
Pull out fuse panel?
by wa2ise. 12/14/18 05:09 PM
Conduit fill Calculations
by gfretwell. 12/08/18 08:39 PM
Swimming Pool question
by HotLine1. 12/05/18 12:37 PM
New in the Gallery:
What is this for?
Plug terminals
Who's Online Now
0 registered members (), 9 guests, and 13 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Conductor Size for AC compressor #194362
05/26/10 12:04 PM
05/26/10 12:04 PM
S
SJT  Offline OP
Member
Joined: Jul 2002
Posts: 241
PATCHOGUE, N.Y.
There is an outside Air Conditioning compressor for Central Air. The name plate running Amps says 19amps. 30 amp breaker at the Panel. Even though the code says #12 is good for 25 amps, the unit should be wired in #10 wire, right? Is there an exception in the 440 section of the code? As far as I know #12's limit is 20 amps. No exceptions? Thanks - Good Day

Work Gear for Electricians and the Trades
Re: Conductor Size for AC compressor [Re: SJT] #194363
05/26/10 12:49 PM
05/26/10 12:49 PM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,323
Estero,Fl,usa
If the "19 Amps" is labeled as the "minimum circuit ampacity" or words to that effect.
Grab a hold of your hat. You could use #14. (per 310.16, 60 degree column).
There was a question on the inspectors test about a 1hp motor on a 120v circuit where the right answer was "40a breaker, 14 ga wire". Strange sounding things happen around motors and HVAC units.
The exception is in 240.4(G) (2008 code or in 240.4(D)ex in earlier versions).


Greg Fretwell
Re: Conductor Size for AC compressor [Re: gfretwell] #194368
05/26/10 03:55 PM
05/26/10 03:55 PM
S
SJT  Offline OP
Member
Joined: Jul 2002
Posts: 241
PATCHOGUE, N.Y.
I seen 240.4(D)(5), saying 12 AWG Copper - 20 amperes. I thought I had to go with that? Is 240.4(G) only refer to Overcurrent Protection, so I would have to go to a #10?
Could I leave #12's? The Electrician already wired the unit with 12's.

Re: Conductor Size for AC compressor [Re: SJT] #194369
05/26/10 04:04 PM
05/26/10 04:04 PM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,323
Estero,Fl,usa
It says

Quote
240.4(D) Small Conductors. Unless specifically permitted in 240.4(E) or (G), the overcurrent protection shall not exceed that required by (D)(1) through (D)(7) after any correction factors for ambient temperature and number of conductors have been applied.
so the whole issue is about overcurrent protection.


Greg Fretwell
Re: Conductor Size for AC compressor [Re: SJT] #194370
05/26/10 04:06 PM
05/26/10 04:06 PM
S
SJT  Offline OP
Member
Joined: Jul 2002
Posts: 241
PATCHOGUE, N.Y.
Table 310.16 (left side) has the * next to #'s 14, 12, and 10. Does the asterik mean you have to keep #12 at 20 amps?

Re: Conductor Size for AC compressor [Re: SJT] #194371
05/26/10 04:11 PM
05/26/10 04:11 PM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,323
Estero,Fl,usa
No that just refers you to 240.4(D) which then further defines the necessary overcurrent protection for small conductors in any use not excepted by 240.4(G) or (E).


Greg Fretwell
Re: Conductor Size for AC compressor [Re: gfretwell] #194375
05/26/10 05:46 PM
05/26/10 05:46 PM
S
SJT  Offline OP
Member
Joined: Jul 2002
Posts: 241
PATCHOGUE, N.Y.
Thanks, I'll go through Article 440 parts 3 and 6.

Re: Conductor Size for AC compressor [Re: SJT] #194377
05/27/10 01:17 AM
05/27/10 01:17 AM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,323
Estero,Fl,usa
The short answer is the label on the condenser rules.
Another interesting read is the U/L marking guide for HVAC equipment. Unfortunately they don't have it online without paying for it.


Greg Fretwell

Featured:

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

 

Member Spotlight
Lostazhell
Lostazhell
Bakersfield, CA (Originally Orange Co.)
Posts: 1,431
Joined: February 2004
Show All Member Profiles 
Top Posters(30 Days)
Popular Topics(Views)
252,249 Are you busy
189,203 Re: Forum
178,888 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.026s Queries: 15 (0.004s) Memory: 0.9941 MB (Peak: 1.1549 MB) Zlib enabled. Server Time: 2018-12-16 22:04:10 UTC