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 :mrgreen:
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.)