Safety Question - External 480v 4 wire receps on Presses

[FIRERESCUE]

Plastic Inj. Molding Machines - anyone have experience with requirements for external 480V 3 Phase general use receptacles mounted to a machine for auxiliary equipment and fed from a remote secondary source? We have 4 receps on each machine. Each recep is 30 Amps and tapped from 60 Amp fused disconnect w/60A fuses. Each piece of auxiliary equipment has its own disconnect, overload and short circuit protection sized per machine as well as corresponding twist lock male plug. The press disconnect powers down all press power but all external auxiliary receps are still live and disconnect is not within sight. We have maintenance personnel arguing with management about no warning signs for secondary power, no shut down procedures and no auxiliary recep power disconnect within sight at the machine. As far as I can tell it is perfectly legal. The argument concerns the auxilliary equipment cords or receptacles that become damaged - operators do not understand that this power is still live even with the press disconnect in the "off" state. I know this is a training and education problem but does anyone see anything wrong by the NEC standards? I looked in the NEC and NFPA 79 Articles as well and all I can find is a reference for warnings when parts are live in a de-energized state due to secondary power sources - which is not the case here. Although I disagree with management due to operator safety concerns I can't seem to give any concrete reference that proves the maintenance teams argument is valid. All wiring was performed by a reputable licensed electrical contractor.
Thanks in advance ........

 

[dlhoule]

Re: Safety Question - External 480v 4 wire receps on Presses

NFPA 79 5.3.1.2 The supply circuit disconnecting means shall disconnect (isolate) the electrical equipment of the machine, including all control circuits, from the supply circuit when required (e.g., for work on the machine, including the electrical equipment). Circuits that are not required to be disconnected by the supply circuit disconnecting means shall comply with 5.3.5

Now if I understand your question correctly, I do not think these outlets would be covered by 5.3.5. In which case they should not have power on with main disconnect off.

Also; IMO These outlets should be such that you cannot insert or remove plug with power on outlet. If you have a bad cord, you can draw enough of an arc to seriously burn the person plugging/unplugging the bad cord.

 

[jtester]

Re: Safety Question - External 480v 4 wire receps on Presses

The molding machine auxilary receptacles I have worked with operate heaters, sprue cutters, etc., that are part of the process, but not a part of the machine itself. Therefor we have not provided wiring through the machine disconnect. They often had a fusible disconnect nearby, but not always.

Jim T

 

[don_resqcapt19]

Re: Safety Question - External 480v 4 wire receps on Presses

Each recep is 30 Amps and tapped from 60 Amp fused disconnect w/60A fuses.

Looks like a problem with 210.21.

210.21(B) Receptacles
(1) Single Receptacle on an Individual Branch Circuit. A single receptacle installed on an individual branch circuit shall have an ampere rating not less than that of the branch circuit.

Don

 

[FIRERESCUE]

Fuses .............

Fuses .............

Sorry Don, I forgot to mention that each recep is seperately fused down to 30A with Class CC fuses ................... which are tapped from the 60A main feed to the machine.