We are installing a new oil filled transformer and will be penetrating the oil pit liner. The drawings indicate the conduit immediately turning up to a field termination cabinet. The conduit is 4" sch 40 PVC, the cable will be 3-1/C 350kcmil. The engineer says the conduit needs to penetrate the liner at a right angle and to use a 90 degree LB fitting to turn up as we don't have room for a sweep. As this will later be filled with stone, is it acceptable to use an LB fitting that will be below grade? I've never done this before, but am drawing a blank if it's permissible. Thanks for any input. Greg
Not Permitted. You must retain access to that LB when installation is complete, just as if it were a junction box.
Invariably, someone at this point will say "but we can remove the stones later." They might even find code language that would allow, say, minor amounts of leaf mulch to conceal outdoor lighting fittings. Nice try; we might as well just eliminate any restrictions on accessibility if we're going to stretch that loophole that far.
You'd be better using another code provision that might let you re-examine 'conduit fill,' and make a sweep using a conduit barely large enough for the cable to enter. Or, for that matter, use a cable that's rated for direct burial.
Renosteinke, thanks for the quick response. That's what I thought, treat the LB like a junction box, you need to retain access. I told the engineer, and he agreed to look for a different solution. I appreciate the quick input. Best regards, Greg
The accessibility requirement for the LB would also apply to a 90 degree fitting for "Flex" or "Sealtite." The requirement does not apply, however, to MC. "MC" is best described as flex that is sold with the wires already in it.
Whether there is a rated MC and fitting for your application is another question.