How serious is it?

[smallfish]

How serious is it not to have bonded to the enclosure, emt stubbing up out of the floor into an open-bottom main distribution panel?
There are four four-inch emt pipes with set screw connectors and couplings, each enclosing a parallel set of 750 kcmil aluminum feeders, each including an equipment bonding jumper sized appropriately and each jumper is terminated to a lug on the panel frame. The other end of the emt is connected to the metal frame of the switchgear by means of an emt connector. The pipe run is over a hundred feet.
Thanks

 

[mikeames]

The risk is the insulation of the wire breaking down, shorting out to the EMT and not clearing the fault. Since the EMT is most likely grounded (but not well) its possible that a short would seriously heat the emt until it clears either through a breaker tripping or the conduit melting.

 

[KevinVost]

I would say 2005 NEC art 250.96 (A) would apply.

 

[active1]

If I understand the post correctly it can create an inpeadiance issure if only 1 side of a metal conduit is grounded and there is a short to ground.

They do make split grounding bushings for conduit.
http://www.electrical-supply.net/category.asp_Q_parentid_E_321_A_subcatid_E_653