As a firefighter, I think of having a fire in a room, or the cockloft under those A/C units. With the damage to the structure, and the building not being designed for the load, having one of those come down on us is a real possibility.
As an EC, do you have any closer pics for us Joe? And which articles are you thinking of in particular?
The one which first pops to mind for me is about having a 15 or 20A GFCI protected "Heating, Air-Conditioning, and Refrigeration Equipment Outlet" on the rooftop, per 210-63 ('96 NEC).
Edited to add - just looked at my NEC - sorry!
[This message has been edited by DougW (edited 05-30-2004).]
Re: Electrical Equipment on Roof Tops#88366 05/30/0408:44 AM05/30/0408:44 AM
Yes, NEC 210.63 calls for one within 25 feet of the HACR units:
210.63 Heating, Air-Conditioning, and Refrigeration Equipment Outlet.
A 125-volt, single-phase, 15- or 20-ampere-rated receptacle outlet shall be installed at an accessible location for the servicing of heating, air-conditioning, and refrigeration equipment. The receptacle shall be located on the same level and within 7.5 m (25 ft) of the heating, air-conditioning, and refrigeration equipment. The receptacle outlet shall not be connected to the load side of the equipment disconnecting means.
FPN: See 210.8 for ground-fault circuit-interrupter requirements.
Article 440 covers this equipment, and 440.14 includes the disconnecting means rules.
Joe Tedesco, NEC Consultant
Re: Electrical Equipment on Roof Tops#88368 05/30/0408:55 AM05/30/0408:55 AM
A big mistake is the disconnect is mounted to the unit on a panel that needs to be removed for unit servicing.
Part of 440.14
The disconnecting means shall not be located on panels that are designed to allow access to the air-conditioning or refrigeration equipment.
Sometimes it is almost imposable to find a mounting place on the unit that is not a removable panel, a condenser coil, a vent for air flow and still provides the 110.26 workspace that some inspectors require and some do not.
Creative use of uni-strut will get you around these issues.
Bob Badger Construction & Maintenance Electrician Massachusetts
Re: Electrical Equipment on Roof Tops#88371 05/30/0409:12 AM05/30/0409:12 AM
More likely an A/C problem but why would there be a pedestal fan sitting up there pointed at one of the condensing units - trying to cover for a too-small or overloaded unit? Around here, they have to build for a 30 pounds per sq. ft. snow load. The rooftop units likely are less than that and would not need any special structural consideration beyoun making the penetrations watertite and distributing the loads.