[RE-wrenches] Cable tray

[Brian Mehalic]

Hello wrenches, question about running conductors in cable tray.  So we
have our allowance in 690.31(C)(2) for using small PV Wire in cable tray
for PV source and output circuits.  I'm trying to determine what adjustment
factor to apply when there are a bunch of small conductors.

392.80(A)(2)(a) and (b) both address single conductor cable in covered
cable tray, but only refer to conductors from 1/0 to 500 kcmil, and 600
kcmil and up.  I'm looking more at 40 or 50 12 AWG conductors (20 to 30
source circuits).  The adjustment factors in 392.80(A)(2) are pretty hefty
- only 60 to 70% of the rated ampacity, but as stated in Table
301.15(B)(17) (conductors in free air, so that helps).

Any guidance would be much appreciated, and thanks for your time,

Brian Mehalic
NABCEP Certified Solar PV Installation Professional™ R031508-59

PV Curriculum Developer and Instructor
Solar Energy International
http://www.solarenergy.org
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