Conductors in a Concrete Trench
Conductors in a Concrete Trench
(OP)
Gentleman, I have an installation where, due to some monumental blunder, wires designed to be overhead in conduit are now to be run in a concrete trench. These are feeding power to various devices using 12-250kcmil (qty 4 of 3-wires) and qty 2 4-wire of 2/0.
I understand that concrete trenches are considered a raceway and as such are subject to ampacity deratings listed in 310.15(B)(2). Is that a correct definition? If so, can some of these conductors be placed in conduit in the trench and somehow be exempt from derating?
The 2/0 bundles are feeding DC to braking resistors only a few times a month, so there should be some diversity, but still the deratings are killing us.
Any suggestions or experience with similar problems would be greatly appreciated.
I understand that concrete trenches are considered a raceway and as such are subject to ampacity deratings listed in 310.15(B)(2). Is that a correct definition? If so, can some of these conductors be placed in conduit in the trench and somehow be exempt from derating?
The 2/0 bundles are feeding DC to braking resistors only a few times a month, so there should be some diversity, but still the deratings are killing us.
Any suggestions or experience with similar problems would be greatly appreciated.





RE: Conductors in a Concrete Trench
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(2B)+(2B)' ?
RE: Conductors in a Concrete Trench
Bill
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"Why not the best?"
Jimmy Carter
RE: Conductors in a Concrete Trench
Other than that I'm not sure what credit code allows for non-continuous loads.
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(2B)+(2B)' ?
RE: Conductors in a Concrete Trench
...(2) Qualified persons with documented training and experience in over 600-volt systems provide maintenance,
monitoring, and servicing of the system."
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(2B)+(2B)' ?