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Understanding these UG ampacity tables

1K views 2 replies 2 participants last post by  Inspectorclouseau 
#1 ·
The CEC uses very similar installation diagrams and ampacity tables for determining UG ampacities as the NEC ( 0-5000V). The installation diagrams show the direct buried cables or raceways installed at 915mm (3') in various sets per phase. A recent Code seminar I attended stated the installations had to comply with the diagrams. The cable could not be installed at 750mm (30") without professional supervision as you say.
Does this sound correct? I always thought that generally the ampacity decreased as the depth increased. Shouldn't I be able to use the ampacity Tables at any depth down to that shown in the diagrams and then need engineering when that depth is exceeded.
 
#2 ·
Of course, we are discussing paralleled underground raceways -- often encased in slurry or concrete, to boot.

1) As long as one is dealing with only one or two pipes -- and the Code is followed -- you are good to go.

2) All big arrays// parallels need to be designed by EEs -- as they can shoulder the blame. ( E & O policies. )

3) Stay with industry standard 'racking.'

I would always expect full details to be called out by seasoned EEs for any and all industrial// institutional// military// government projects.

The economics of major trench excavation are not my concern, for the primary contractor handles such matters.

But then, you're up in British Columbia. Maybe everything is different. :rolleyes:
 
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