Everything failed at the same time… I’m sorry to hear that, it looks like your maintenance provider didn’t do much to prevent it… I’ve been there - http://checkthishouse.com/3879/furnace-ac-seasonal-inspection-do-you-trust-your-hvac-guy.html
Back to your question, I bolded section of a paragraph below stating that the protective pan has to extend 3” beyond the equipment’s footprint (from IMC - International Mechanical Code). This is a link to original paragraph from 2006 IMC - http://publicecodes.citation.com/icod/imc/2006f2/icod_imc_2006f2_3_sec007_par004.htm
There’s also a possibility that your jurisdiction requires something other than in the paragraph below, more or less protection.
307.2.3 Auxiliary and secondary drain systems.
In addition to the requirements of Section 307.2.1, a secondary drain or auxiliary drain pan shall be required for each cooling or evaporator coil or fuel-fired appliance that produces condensate, where damage to any building components will occur as a result of overflow from the equipment drain pan or stoppage in the condensate drain piping. One of the following methods shall be used:
An auxiliary drain pan with a separate drain shall be provided under the coils on which condensation will occur. The auxiliary pan drain shall discharge to a conspicuous point of disposal to alert occupants in the event of a stoppage of the primary drain. The pan shall have a minimum depth of 1.5 inches (38 mm), shall not be less than 3 inches (76 mm) larger than the unit or the coil dimensions in width and length and shall be constructed of corrosion-resistant material.
Metallic pans shall have a minimum thickness of not less than 0.0276-inch (0.7 mm) galvanized sheet metal. Nonmetallic pans shall have a minimum thickness of not less than 0.0625 inch (1.6 mm).
A separate overflow drain line shall be connected to the drain pan provided with the equipment. Such overflow drain shall discharge to a conspicuous point of disposal to alert occupants in the event of a stoppage of the primary drain. The overflow drain line shall connect to the drain pan at a higher level than the primary drain connection.
An auxiliary drain pan without a separate drain line shall be provided under the coils on which condensate will occur. Such pan shall be equipped with a water-level detection device conforming to UL 508 that will shut off the equipment served prior to overflow of the pan. The auxiliary drain pan shall be constructed in accordance with Item 1 of this section.
A water level detection device conforming to UL 508 shall be provided that will shut off the equipment served in the event that the primary drain is blocked. The device shall be installed in the primary drain line, the overflow drain line, or in the equipment-supplied drain pan, located at a point higher than the primary drain line connection and below the overflow rim of such pan.
Exception: Fuel-fired appliances that automatically shut down operation in the event of a stoppage in the condensate drainage system.
It all refers to unit / coil dimensions, and there’s nothing about extending underneath the drain tubing attached to this unit. I can’t see your installation but in some cases it would be logical to go that extra step and widen the pan (if constructed in location) to provide more protection for a suspect area… or reroute the drain pipe so it’s still above some factory made safety pan. Some people do it, some will unfortunately not use common sense.
One thing the maintenance people should be responsible for is removing all the debris from inside the drain line, that’s one of the main items on the maintenance list; you paid them for cleaning it!
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