TRANE Nameplates - In The Future

[Paul W. Abernathy]

Hey Guys (and Gals),

I just did a seminar this past Friday for a group of electricians and found some interesting news. It appears that in the future TRANE will not be putting on it's nameplates for AC Units the MCA and MOP information anymore. They are simply going to put the MOP ( Maximum Overcurrent Protection ). The problem in their view is that many people do not understand what it means by putting the minimum circuit ampacity and the maximum overcurrent protection and they feel that the majority of installers simply install the branch circuits sized to meet the OCPD that is being installed.

While the National Electrical Code has a method for determining all this information, it has always been the practice to simply look at the nameplate for this information. Now, granted that if you size the branch circuits supplying this AC Comp. Unit the same size as the Maximum Overcurrent Protective Device given on the new nameplate then you will be fine and compliant. However, the Minimum Circuit Ampacity calculation within the NEC would still be applicable if used.

Imagine that...i got through that entire thing and did not use one code reference.....imagine that

[Robert Meier]

I find that to be odd, and actually stupid, since it flies in the face of the NEC requirement to contain such information. Although Paul didn't cite any code I will:

440.4 Marking on Hermetic Refrigerant Motor-Compressors and Equipment.
(B) Multimotor and Combination-Load Equipment. Multimotor and combination-load equipment shall be provided with a visible nameplate marked with the maker's name, the rating in volts, frequency and number of phases, minimum supply circuit conductor ampacity, the maximum rating of the branch-circuit short-circuit and ground-fault protective device, and the short-circuit current rating of the motor controllers or industrial control panel. The ampacity shall be calculated by using Part IV and counting all the motors and other loads that will be operated at the same time. The branch-circuit short-circuit and ground-fault protective device rating shall not exceed the value calculated by using Part III. Multimotor or combination-load equipment for use on two or more circuits shall be marked with the above information for each circuit.
Exception No. 1: Multimotor and combination-load equipment that is suitable under the provisions of this article for connection to a single 15- or 20-ampere, 120-volt, or a 15-ampere, 208- or 240-volt, single-phase branch circuit shall be permitted to be marked as a single load.
Exception No. 2: The minimum supply circuit conductor ampacity and the maximum rating of the branch-circuit short-circuit and ground-fault protective device shall not be required to be marked on a room air conditioner complying with 440.62(A).
Exception No. 3: Multimotor and combination-load equipment used in one- and two-family dwellings, cord-and-attachment-plug-connected equipment, or equipment supplied from a branch circuit protected at 60 A or less shall not be required to be marked with a short-circuit current rating.

[James H. Bushart]

The very worst HVAC contractor in our codeless county of Barry in Missouri (where "electricians" have worked for "forty years" without ever referring to the National Electric Code)...is a Trane distributor.

As a "forty year" electrician, he can wire 'em up pretty good....but he is clueless when it comes to air distribution, ventilation, and calculating capacity requirements.

The engineer who designed a public building that was being constructed for a college called for nine heating/cooling units....but our Trane guy figured that by eliminating the intake of fresh outside air, he could get by with installing four. Less fresh air means less cooling and heating, right? 100% recycled air in a public building. Sounds refreshing, doesn't it?

We don't need codes down here in the Ozarks.....(for that matter, we don't really need any colleges, either.)