Bonding Motors -- req'd?

[lakee911]

Do motors need to be explicitly grounded?

I have an install of a 650HP Siemens motor that has two 1/2-13 UNC ground bolts on the motor frame and I noticed that the electrical Contractor hadn't bonded the frame.

The literature on the motor simply states the following:

Motors should be installed and grounded per local and national codes.

All that I've found in the NEC is the following:

(E) Equipment Grounding Connections. A means for attachment of an equipment grouning conductor termination in accordance with 250.8 shall be porovided at motor terminal housings for wire-to-wire connections or fixed terminal connections. The means for such connections shall be permitted to be located either inside or outside the motor terminal housing.

Exception: Where a motor is installed as a part of factory-wired equipment that is required to be grounded and without additional connections being required at the terminal housing during equipment installation, a seperate means for motor grounding at the motor terminal housing shall not be required.

That's all I could find. So, I'm not sure if it needs to be bonded or not.

The Contractor tells me that the plans do not show a ground cable run out to the blower motors and that there is metal to metal contact between the motor and skid.

The motor was actually field installed on the skid, and I don't think the skid was bonded. It's sitting on a concrete platform, but it's probably attached with epoxy anchors.

I'm not sure how to proceede here. Any advice?

Thanks!

 

[don_resqcapt19]

closed duplicate