NFPA 79- Electrical Standard for Industrial machinery 1997 edition.
page 79-13 chapter 7 Supply circuit disconnecting means.
7.1 general requirements - a disconnecting menas shall be provided for each incomming supply circuit.
my concerns
1. With the power supply on the line side of the disconnect, how will you turn off the power to the power supply?
you have bypassed the main machine disconnect and put it on the line side of the disconnect. the plant bussbar / disconnect is
25 ft in the air and not readily accessable. Put yourself in this situation, YOU are the one who forgets or is unaware the power supply
is not turned off with the machine disconnect, YOU touch a live wire and also connectyed to ground, and YOU are now the one being electrocuted. How will your coworkers get YOU
free? I forgot one time that a machine had 2 sources of power during the july 4th shutdown at a plant, soaking wet with sweat. Had my elbows not been the source
of contact from 110 to ground, i would not be here (the electrical shock caused my elbows and muscles to contract and knocked me out of the panel).
Explain that to OSHA and and corporate management as your family files a mega lawsuit against the company.
2. machines with more than one source of power must have a legend stating this. typically this is interface wiring to another
machine or controller with yellor or orange wires.
to me, its a very bad idea. i was hoping that someone else would reply with a better answer.
regards,
james