bonding jumper ?

[randypape]

hello, when we wire subpanels for enclosures for machines, i'm having trouble finding in the NEC what size conductor for bonding jumpers for connecting the enclosure doors ,sub panels ,etc. to our main terminal block point. i know when you go by breaker size for say a 60 amp brkr you use 8awg for the equipment bonding jumper, but what about the other things i'm talking about that are just bonding jumpers?
thanks Randy

 

[petersonra]

hello, when we wire subpanels for enclosures for machines, i'm having trouble finding in the NEC what size conductor for bonding jumpers for connecting the enclosure doors ,sub panels ,etc. to our main terminal block point. i know when you go by breaker size for say a 60 amp brkr you use 8awg for the equipment bonding jumper, but what about the other things i'm talking about that are just bonding jumpers?
thanks Randy

These are equipment grounding conductors. They would be sized according to the chart for such things.

However, there is no code reason to bond these things together, except possibly the door, as normally the ground lug is connected to the panel, and the panel is bonded to the enclosure through the attachment stud.

The only thing that needs to be routinely bonded separately might be the doors, depending on whether it is required for the enclosure you are using. Some are listed as not needing it.

You might want to take a look at NFPA79, as it deals with control panels for machinery. Really, what you do inside a control panel is not covered by the NEC. Only the wiring up to the panel is covered by the NEC, what is inside it is not.

Normally, I spec a min #12 ground wire to the door. This is mostly for mechanical strength and not for any electrical reason.

 

[randypape]

thanks for the reply

thanks for the reply

hello this is why i asked because it seems to be the topic of confusion at work ,in that evrey sub panel,door, disconnect, etc have a ground wire on it leading back to a central point on the main sub panel in the main enclosure.
i thought this might be overkill, but i'm just an apprentice thanks again Randy:smile:

 

[petersonra]

hello this is why i asked because it seems to be the topic of confusion at work ,in that evrey sub panel,door, disconnect, etc have a ground wire on it leading back to a central point on the main sub panel in the main enclosure.
i thought this might be overkill, but i'm just an apprentice thanks again Randy:smile:

The stuff needs to be bonded together, but it may not be necessary to do anything at all to accomplish that.

 

[bphgravity]

Section 250.102 would likely be sufficient for sizing the conductors you are referring to.