Question : Is a bonding bushing required when you have 277 volt wiring going through 1/2" liquidtight flexible metal conduit ( sealtight). This is terminated into a 4 square box that has concentric / eccentric knock outs. The knock outs are 1/2" to 3/4"
with only the 1/2" taken out.
I say yes a bonding bushing is required as per 250.97 another electrician say no you don't need them because its sealtight not a metal raceway like rigid conduit.

But LFMC is a metal raceway and in some cases can be used as the EGC. I've read 250.97 and 350.60 and 250.118 (C) and my educated guess would be YES, a bonding bushing is needed if this run is more than 6.'

I look forward to reading more replies on this matter but I have to leave for school now.

IMHO you win the beer. Unless the box is listed to provide the required bonding with only the 1/2" ko removed. Some of them are.

I see it the same as George.

OK, add a another agreement

John

According to the UL white book, all outlet boxes (such as four inch) are suitable for bonding over 250 volts, without additional bonding, even with concentric.

Thanks Ryan, I thought I'd read that somewhere but I wasn't sure so I appreciate that info as does everyone else on this BB.

I was reading about the UL listing on the new MC/ap connectors and the fact that they are rated for use without a ground wire on boxes with both concentric and eccentric knock outs on UL listed boxes caught my eye. In some applications you do not have to bond as long as the box is approved