Dale Hayes
Senior Member
Another question about Control Transformers.
The main power supply is 480V, 3phase, and separate ground wire.
A 480V to 120V 500VA control transformer supplies 120V 1-phase power to an Industrial Control Panel control circuit.
The control transformer has two connection points on the secondary side: X1 and X2.
X1 is "hot".
X2 is the "neutral" and it is also "grounded".
Can X2 be grounded at the sub-panel or is the X2 grounded wire to be routed back to the main service equipment?
If the X2 "neutral" is grounded at the sub-panel, then the X2 neutral/ground connection is "downstream" of the main service entrance grounded neutral.
I read where a separate, insulated, neutral wire always must run between the service equipment and the sub-panel.
Where is the control transformer X2 ground connection to be made?
The main power supply is 480V, 3phase, and separate ground wire.
A 480V to 120V 500VA control transformer supplies 120V 1-phase power to an Industrial Control Panel control circuit.
The control transformer has two connection points on the secondary side: X1 and X2.
X1 is "hot".
X2 is the "neutral" and it is also "grounded".
Can X2 be grounded at the sub-panel or is the X2 grounded wire to be routed back to the main service equipment?
If the X2 "neutral" is grounded at the sub-panel, then the X2 neutral/ground connection is "downstream" of the main service entrance grounded neutral.
I read where a separate, insulated, neutral wire always must run between the service equipment and the sub-panel.
Where is the control transformer X2 ground connection to be made?
