How to ground a 120V separately derived circuit. - 03/30/05 09:22 PM
I need to hook up a 208v motor. The control panel will contain 120V
control circuit and a 208/120V transformer.
I looked through the code book to find what I should do as far as grounding the 120V control circuit. Should I just jumper one leg of
the secondary to the control box enclosure?
Before you say yes, let me tell you two reasons why I think that might not be legal.
1) The system is 120V, therefore it has be grounded, meaning, one of
the legs (either X1 or X2) shall be connected to a grounding electrode.
2) Now, about the grounding electrode... The code 250.30 (A) (4) states that the electrode of a separately derived system has to be as
near as practicable to the same area as the grounding electrode conductor conenction to the system. So, I was thinking I might have to run a wire (grounding electrode conductor) through the control panel enclosure, then run it to a nearest metal structure.
Am I right? Am I wrong?
control circuit and a 208/120V transformer.
I looked through the code book to find what I should do as far as grounding the 120V control circuit. Should I just jumper one leg of
the secondary to the control box enclosure?
Before you say yes, let me tell you two reasons why I think that might not be legal.
1) The system is 120V, therefore it has be grounded, meaning, one of
the legs (either X1 or X2) shall be connected to a grounding electrode.
2) Now, about the grounding electrode... The code 250.30 (A) (4) states that the electrode of a separately derived system has to be as
near as practicable to the same area as the grounding electrode conductor conenction to the system. So, I was thinking I might have to run a wire (grounding electrode conductor) through the control panel enclosure, then run it to a nearest metal structure.
Am I right? Am I wrong?