Junkman
Well-known member
I have just spent a lot of time reading, and rather than ask my question in one of those other threads, and muddy the waters, I will start a new thread.
I recently was given an electrical box that came from a manufacturing facility, and the box says to only power it from the master uninterruptable power supply. The box consists of five 110 volt 15 amp receptacles, and one 30 amp 4 prong receptacle (L14-30R). At the end of the power cord that is attached to this box, is a 4 prong twist plug (L14-30P). The 110 volt receptacles have individual push button circuit breakers. I opened the box to see how it was wired, and all the 110 outlets have their ground wires going back to a single stud on the case, and the green wire from the 4 prong twist plug goes to this terminal. Half of the black 110 volt wires go to the red wire on the L14-30R receptacle and the other half go to the black wire on the L14-30R receptacle. The 4th wire is yellow, and it goes to the silver terminal on the L14-30R, along with all the white wires coming from the 110 receptacles.
I understand how I should wire the receptacle that I want to power this box at my electrical panel (white to neutral, green to ground, red to one terminal of the breaker, and black to the other terminal of my 220 breaker).
Now, for the question, why isn't there a green jumper wire from the case to the green terminal on the L14-30R receptacle? And, why is it that they specify that this box shouldn't be powered from any other source except from that uninterruptable power supply?
I recently was given an electrical box that came from a manufacturing facility, and the box says to only power it from the master uninterruptable power supply. The box consists of five 110 volt 15 amp receptacles, and one 30 amp 4 prong receptacle (L14-30R). At the end of the power cord that is attached to this box, is a 4 prong twist plug (L14-30P). The 110 volt receptacles have individual push button circuit breakers. I opened the box to see how it was wired, and all the 110 outlets have their ground wires going back to a single stud on the case, and the green wire from the 4 prong twist plug goes to this terminal. Half of the black 110 volt wires go to the red wire on the L14-30R receptacle and the other half go to the black wire on the L14-30R receptacle. The 4th wire is yellow, and it goes to the silver terminal on the L14-30R, along with all the white wires coming from the 110 receptacles.
I understand how I should wire the receptacle that I want to power this box at my electrical panel (white to neutral, green to ground, red to one terminal of the breaker, and black to the other terminal of my 220 breaker).
Now, for the question, why isn't there a green jumper wire from the case to the green terminal on the L14-30R receptacle? And, why is it that they specify that this box shouldn't be powered from any other source except from that uninterruptable power supply?
