The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!

Featured:
   

2017 NEC and Related
2017 NEC
Now Available!

   
Recent Posts
Safety at heights?
by Trumpy
27 minutes 52 seconds ago
Old Bath Fan
by gfretwell
Today at 01:38 AM
Search Function
by Webmaster
Yesterday at 11:13 PM
Forum Software Upgrade coming soon...
by Webmaster
Yesterday at 09:17 PM
ESA Arc flash course
by frank
Yesterday at 04:25 PM
New in the Gallery:
Desk-mounted "power-board"
Top Posters (30 Days)
Webmaster 30
HotLine1 21
Ruben Rocha 16
gfretwell 13
ghost307 12
Who's Online
1 registered (Trumpy), 0 Guests and 167 Spiders online.
Key: Admin, Global Mod, Mod
Page 1 of 2 1 2 >
Topic Options
Rate This Topic
#100026 - 10/05/06 03:12 PM A Code compliant installation?
ShockMe77 Offline
Member

Registered: 06/11/05
Posts: 823
Loc: Rahway, New Jersey
Air conditioning condensing unit has a minimum ampacity rating of 18 amps.

A maximum over current protection device rating of 30 amps.

A 60 amp rated non-fused diconnect is used and installed in a readily accessible location.

14 AWG wire is run to the disconnect, and then #14 THWN to the condensing unit.

A double-pole 30 amp circuit breaker is installed at the panel.

Is this an NEC compliant installation?

Top
2017 / 2014 NEC & Related Books and Study Guides
#100027 - 10/05/06 03:44 PM Re: A Code compliant installation?
George Little Offline
Member

Registered: 01/18/04
Posts: 1492
Loc: Michigan USA
Absolutely Green Sticker time.
_________________________
George Little

Top
#100028 - 10/05/06 04:31 PM Re: A Code compliant installation?
Trick440 Offline
Member

Registered: 08/15/05
Posts: 248
Loc: Waterford, MI, USA
I need some clarification on this one.

How can you use a 30a breaker to protect 14g wire?

heck I guess I need to know how 14-2 supports 18a aswell.

[This message has been edited by Trick440 (edited 10-05-2006).]
_________________________
Shake n Bake

Top
#100029 - 10/05/06 04:41 PM Re: A Code compliant installation?
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
I agree with George.

Trick first off 14 AWG is rated anywhere from 20 to 25 amps depending on the insulation and terminations.

On typical branch circuits 240.4(D) requires us to use a 15 amp over current device.

However for HVAC units 240.4(G) applies and we can use 14 AWG up to the rating in 310.16 and the short circuit and ground fault protection can be as allowed in 440.6
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts

Top
#100030 - 10/05/06 04:59 PM Re: A Code compliant installation?
Trick440 Offline
Member

Registered: 08/15/05
Posts: 248
Loc: Waterford, MI, USA
Can't wait to pull this one on my boss.. lol.

Thank you for the code refs. and explanation.
_________________________
Shake n Bake

Top
#100031 - 10/05/06 05:24 PM Re: A Code compliant installation?
ShockMe77 Offline
Member

Registered: 06/11/05
Posts: 823
Loc: Rahway, New Jersey
Trick, this is exactly why I posted this. I did an over/ under split-system A/C install today and was talking to the HVAC contractor. He saw me looking at the specs on both CU's and told me, "just run a 30 amp 10/2 wire."

So I said, "ok, but I could really just run 14 wire and it'd be ok by NEC standards."

He says, "I've never heard of that so don't so it."

^^
(this coming from the HVAC guy, not an electrician)

Of course, the better install is to run the maximum size wire and the maximum size OCPD, I'm sure most would agree. But the point is, it can be done and pass inspection, and damn it felt good to hold my own in this discussion.

Thanks ECN!

Top
#100032 - 10/05/06 06:10 PM Re: A Code compliant installation?
HotLine1 Offline


Member

Registered: 04/03/02
Posts: 6831
Loc: Brick, NJ USA
Ron:
Ya did good! Just keep watching the mfg nameplates. Only other consideration could possibly be voltage drop, dependent on the run. That's my opinion, when ya cut it close.

John
_________________________
John

Top
#100033 - 10/05/06 08:12 PM Re: A Code compliant installation?
ShockMe77 Offline
Member

Registered: 06/11/05
Posts: 823
Loc: Rahway, New Jersey
Thanks John!

Top
#100034 - 10/05/06 09:44 PM Re: A Code compliant installation?
macmikeman Offline
Member

Registered: 07/16/02
Posts: 718
Loc: Honolulu, Hawaii
Most of the mini split systems I have done will list the max fuse or circuit breaker, and the minimum ampacity of the wiring. What I've noticed is they tend to want to protect thier machines from overworking and usually exceed code a bit on the minimum ampacity labeling. Code says go with what is on the label.

Top
#100035 - 10/06/06 06:09 AM Re: A Code compliant installation?
mountainman Offline
Member

Registered: 01/29/02
Posts: 54
Loc: Richmond Va. U.S.A.
iwire, what about 240.6? In order for this to be code compliant you would need a 25 ampere breaker to comply with 240.4(B). IMHO
thanks Joe

Top
Page 1 of 2 1 2 >


ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals