A vendor is proposing supply of an industrial control panel designed for redundant 120 VAC power supply. They are using a single pole transfer switch within the panel to switch from primary to backup power, requiring the neutral of the two sources to be tied together at the control panel. Our application will have the two sources from different load centers (although the neutrals for both load centers are tied to the same ground).
I think they need to change their design to separate the neutrals in the panel as a design issue. Can anyone point me to a code section which would prohibit joining the neutrals in the control panel?
I think they need to change their design to separate the neutrals in the panel as a design issue. Can anyone point me to a code section which would prohibit joining the neutrals in the control panel?