Re: 4/0 cable into the back of a 3 1/2 inch deep panel
Alan Manche is a very intelligent person and well respected in our industry. As a side note to this, I have attended quite a few of the national seminars and the disputes that occur there between individuals is not much different than the interesting ones we have here
), I think that UL requirements and NEC do not always match each other in their intent, and for field installers as opposed to factory installers we need to focus on the NEC.
It is my understanding that UL 83 wire bending radius is for factory installed bending radius (which is under more control and performed with machines) and tested by the manufacturer at the factory. I am sure you can recall some manufactured equipment with factory bends that are 90 degree angles
, so one does not measure the depth of the enclosure, but the distance from the back of the enclosure to the lugs.
Think about this: when you are wearing a long sleeved shirt and you bend your elbow, you can feel the pressure it exerts on the sleeve. Now picture in your mind how this will affect the insulation on the back of one of those sharp bends.
Pierre