Originally Posted By: jtedesco
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THE RIGGED RECEPTACLE
|Randy Barnett, senior instructor, American Trainco, Englewood, Colo., sent me this photo of what was left of a receptacle that was installed in a large Midwest hospital.
The maintenance technician, who brought the receptacle to one of Barnett's training classes, said after he plugged in his vacuum cleaner and turned it on, the receptacle immediately exploded!
Investigation by the hospital's electric shop revealed that the receptacle had been improperly connected to a 480V circuit.
Luckily for him the vacuum wasn't on when he plugged into the receptacle.
You might ask yourself, How could a 120V receptacle be wired into a 480V system?
During a recent remodeling project at the hospital, a contract electrician needed some temporary 480V power, so he rigged a 120V receptacle to get the job done.
One can only wonder how he modified the plug he was using at the time. When asked about the situation, he said he simply forgot to disconnect it after he was done with his project.
Aside from the fact that the installation violates the Code's requirements that prohibit the use of equipment for a purpose for which it's neither suitable nor listed (110.3), the issue raises questions about whether any such electrician could be considered qualified.
Food for thought, watch out for mixed and crossed voltages that could result in a similar hazard.
Joe Tedesco, NEC Consultant