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If AC plate says max 45, then max 45 it is. If 50 was ok, they'd say max 50.
This has been discussed a number of times, not that I'm suggesting you shouldn't have posted it, just a reminder that the archive is a great resource.

The problem is that 45 amp breakers are rare except at a real live wholesale house. The breaker or fuse should be 45 amps in this application. Check out 240.6 in the NEC for a run down on standard sizes. Good info to be had...

- SECTION M1307- - APPLIANCE INSTALLATION- - - M1307.1 General. Installation of appliances shall conform to the conditions of their listing and label and the manufacturer's installation instructions. The manufacturer's operating and installation instructions shall remain attached to the appliance.


IRC 2003,
--E3602.11 Branch circuits for air-conditioning and heat pump equipment. The ampacity of the conductors supplying multimotor and combination load equipment shall not be less than the minimum circuit ampacity marked on the equipment. The branch-circuit overcurrent device rating shall be the size and type marked on the appliance and shall be listed for the specific purpose.


G2408.1 (305.1) General. Equipment and appliances shall be installed as required by the terms of their approval, in accordance with the conditions of listing, the manufacturer’s instructions and this code. Manufacturers’ installation instructions shall be available on the job site at the time of inspection. Where a code provision is less restrictive than the conditions of the listing of the equipment or appliance or the manufacturer’s installation instructions, the conditions of the listing and the manufacturer’s installation instructions shall apply.

Just because someone can't/won't take their arse to the supply house doesen't make it right. Write'em-up everytime.


Rich

__________________
"If con is the opposite of pro, is Congress the opposite of progress?"
Richard Rushing, HCRI
Duncanville, Tx.

Funny how many people don't understand the word "maximum."

I was at an evening H.I. meeting a couple of years ago. The HVAC company doing the presentation said that they frequently drop in breakers larger than the data plate listing and saw no problem with doing so. Then someone asked what happens to the compressor's warranty. The tech's response was that it would probably be voided. No duh! Least he was smart enough to realize that.

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Eric Barker
Moraine Woods Consulting, Inc.
Barrington, IL