breaking the motor contol circuit

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toddelec2

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Does anyone see a problem with extending the 110 volt control circuit of a magnetic starter to the remote loction of the three phase controlled motor. A single pole switch mounted at the motor that breaks the control circuit is the motor disconnecting means. With no way to energize the starter coil all poles of the motor circuit remain open.
 
I cannot quote the NEC section but am sure this setup would not suffice as the motor disconnecting means.

Here is an example of why: someone could still open up the motor starter enclosure and manually push in the starter. The 480VAC line voltage path is now completed to the motor and someone gets hurt.

If a safety disconnect is installed between the starter's load side and the motor and it is locked open then there should be no danger.
 
no no no and I dont have the code sections in front on me..because you can disconnet the 110V it will denergize the coil but could have no effect on the other voltage..it has no affect if one of the contacts are welded shut..Then the motor would not run but one phase or two could still be energized..it does not meet osha regs, industrial standards, or NEC but I would have to look them up..but I would bet that there are several here who would quote them by heart..coulter, bob, Jraf, marc and the list goes on..kind of like the beat goes on now hum a few bars of that...:smile:
 
toddelec2 said:
Does anyone see a problem with extending the 110 volt control circuit of a magnetic starter to the remote loction of the three phase controlled motor. A single pole switch mounted at the motor that breaks the control circuit is the motor disconnecting means. With no way to energize the starter coil all poles of the motor circuit remain open.
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Absolutely not, no way, never. :)

You can bring the control circuit over there and have a have a stop button there, you still have to have a disconnecting means at the motor.

430.103 requires the disconnecting means to open all supply conductors, your single pole switch only opens the control circuit.
 
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toddelec2 said:
Does anyone see a problem with extending the 110 volt control circuit of a magnetic starter to the remote loction of the three phase controlled motor. A single pole switch mounted at the motor that breaks the control circuit is the motor disconnecting means. With no way to energize the starter coil all poles of the motor circuit remain open.
Click to expand...

Actually this is not really an NEC issue except for the previously cited 430.103. However, OHSA, NFPA70E, and NFPA 79 do not accept only opening the control circuit as a valid LOTO method.
 
29 cfr 1910.305 j 4 motors.........this OSHA rule applies and mirrors what iwire is saying...........basically you cannot use a control circuit for control of energy, you have to disconnect all ungounded conductors simultaneously. (i.e. 480 vac 3 ph)
 
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