250.97 Bonding at 480 Volt MCC

[meauxdp]

We are installing a 480 volt MCC. All of the feeder and load circuits are in armored flexible cable. Cables are glanded with Hawke glands and terminated at the MCC with Myers Hubs. Is bonding required at the MCC.

 

[Smart $]

Yes and no. See 250.97 and 250.100. The "no" is in non-hazardous locations where the conditions of 250.97 Exception are met.

 

[meauxdp]

We have installed Crouse Hinds hubs with Grounding tabs, question is are we required to add the bonding wire or is the hub covering the requirement

 

[Smart $]

We have installed Crouse Hinds hubs with Grounding tabs, question is are we required to add the bonding wire or is the hub covering the requirement

I cannot answer your question as posed because I am perplexed by your method of connection. I typically associate an armored-cable-to-enclosure connection as using a listed [for the] armored cable connector. Additionally, please explain what you percieve as questionable regarding the exception to 250.97 and your installation. The intent is "to provide a reliable bonding connection" from enclosure to metal sheath.

 

[meauxdp]

The cables are glanded with Hawke Cable Glands and the gland is made up to a Crouse Hinds STXG Myers Hub. The hub is listed for grounding, question is, is a bond wire required to meet the listing and if so what woud be the reference for sizing the bond.

 

[Smart $]

The cables are glanded with Hawke Cable Glands and the gland is made up to a Crouse Hinds STXG Myers Hub. The hub is listed for grounding, question is, is a bond wire required to meet the listing and if so what woud be the reference for sizing the bond.

Here's an image off Hawkes website of their industrial gland...

I am wondering why it is not directly connecting to the enclosure. Myers Hubs are typically used for conduit terminations to enclosures.

Whether or not the hub itself requires a bonding jumper is subject to the details of connection to the enclosure coupled with the requirements of 250.97, its permissions to deviate under the exception, and 250.100 (which essentially nullifies 250.97 Exception). Without you providing those details, I cannot say whether or not a bonding jumper is required. What I can say is, if in doubt, add the jumper! ...and as I recall it has to be sized the same as the EGC.