Short Circuits
Mar 1, 2007 12:00 PM
The Flame Thrower
The plant I recently relocated to uses a complicated HVAC system to deal with chemical fumes and humidity as well as heating and cooling. My new supervisor, not well versed in the electrical field, was quite concerned about a noise he heard coming from an “electrical box.” When he directed me to the device, I quickly diagnosed the trouble. It was a rusty armature in a Size 2 combination motor starter and disconnect. I saw this as an easy opportunity to show my skills in correcting electrical problems quickly. After removing the armature, I carefully resurfaced and cleaned it in the shop. Back at the enclosure, I sprayed the lower, hard-to-reach areas of the contactor to remove some rust and then reassembled the unit. I was pleased the process had only taken 10 minutes. Knowing the contactor would pick up just after racking in, I was expecting to hear only a slight hum from the enclosure. However, as I closed the disconnect flames billowed out between the bottom of the cabinet and door. I quickly racked it out and opened the door to find that the manufacturer's literature, which was being stored in the bottom of the cabinet, was in flames. I quickly pulled out the paper and soon found several wires had damaged insulation. Unfortunately, I now had to rewire the starter. My advice to you is never use contact cleaner on a live circuit. If you do, make sure it isn't flammable.
Mike Owens
Indianapolis
Plumber's Water Show
In a chemical plant where I worked, the soda products unit was undergoing major production improvements, including bringing in more water and electricity. The plumbers made the final connection to the 3-inch galvanized water pipe they had stubbed in earlier, and turned on the water. Suddenly, everything in the plant went silent. Water was spraying out of every starter fed from the wiring gutter the 3-inch conduit was connected to.
Walter E. Wallis, P.E.
Middletown, N.J.
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