Enclosure Bonding

[ASimmons23]

Quick question about bonding of enclosures: I have several control panels and junction boxes being installed in the field and while the enclosures are grounded to the system ground loop, the doors are not bonded to the enclosure. Does this pose a shock hazard? Also, is there any Code requirement that says you have to bond the doors of a metal enclosure to the enclosure box? I have searched article 250 (and any referenced articles) and have not come up with anything but the field says this is still a problem that needs to be resolved. The boxes are located in a non-hazardous area. Any help is appreciated.

 

[waross]

When electrical devices are mounted in the metal door of an enclosure, the door is grounded by a jumper. The hinges are not usually accepted as a dependable ground path.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[ASimmons23]

That is the conclusion I came to as well, but if there are no devices mounted in the door (only the back panel of the enclosure) does the door need to be bonded anyway?

 

[waross]

In my opinion that is a judgment call. Some do and some don't.
Does anyone know of any industry specific codes that address this issue? Possibly API codes?

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[ASimmons23]

Thanks for all your help, I think you are right, its a judgement call and field has decided to go ahead and bond the doors to the enclosure. Better to be safe than sorry.

 

[SteveSmith]

Only piano hinges are acceptable to UL for bonding.

 

[DRWeig]

What SteveSmith said. If not a full piano hinge, you gotta bond with a conductor if bonding is required.

UL508 / UL508A covers the need for bonding "...all noncurrent carrying metal parts that are exposed or that are able to be contacted by persons during normal operation or adjustment of the equipment, and that are able to become energized due to a breakdown of insulation, loose wiring connection, or electrical disturbance."

If a hot wire in your panel could be unhooked or broken so that it flops against the door, bonding is required. If not, there is wiggle room for a judgement call.

Good on ya,

Goober Dave