Obsolete Industrial


480V Contactor Coils

3rdshiftguy

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480V Contactor Coils
« on: August 19, 2015, 04:06:AM »
Hello guys,
I have a question regarding 480V contactor coils. I understand that wiring a control circuit with 480V is not acceptable for safety reasons, but there is the grandfather situation that I am confused with.

Are old 480V contactor coils grandfathered in? I need to replace a 480V coil (15D21G4) and I don't know if I have to rewire the controls or can I just buy another 480V coil.

Let me know your thoughts or if anyone knows that it definitely not an accepted practice to still use the 480V coils.

Thank you!
Allen
(---The 3rd Shift Guy---)


Cheller

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Re: 480V Contactor Coils
« Reply #1 on: August 21, 2015, 04:06:AM »
480V in push button and operator controls was never a good idea. OSHA or NFPA codes may dictate the use of 24V in control circuits but the grandfather situation is a good question.

24V does not ordinarily have to be guarded and covered up, so working on the controls with the box open and power on is safer than higher voltage controls.

Since the "higher authorities" like everything closed up before power is applied for 480V, it may just be better to reconfigure the control circuit to today's standards and disregard whether or not you can get away with the grandfather rule.

Higher voltage require arc-flash protection and may not be the safest thing for an operator in the event of a shorted switch or push button.
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wrenchturner

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Re: 480V Contactor Coils
« Reply #2 on: September 04, 2015, 04:07:AM »
I have worked on old manual machine tools where the start stop buttons were 480V and never like doing so. It seems like a recipe for disaster. If I were updating controls, I would personally change (or have them changed) to a safer working voltage. If an inexperienced maintenance person ever got his hands in there without knowing the machine well, it could have some pretty serious results. Just my two cents...

Thank You,
The Wrench Turner

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