I once heard that you don't have to ground a metal box with the equipment grounding conductor if it is only used as a raceway, Meaning there are no splices in it. Is this true? 250.80 I think says you can not do this unless it is a short run, but they don't specify what a short run is.
I was leaning on a metal water pipe in a chicken house one day about to work on a 4 square junction box mounted on a wooden backboard.
The junction box was fed with romex and the ground wire was cut off.
The hot had rubbed into the side of the metal 4 square box.
As soon as I reached out touched this metal box, every aspect of poor bonding practices went through me.
Think of it that way.
The metal box needs a pathway back to the source either by metal conduit or a grounding conductor to quickly facilitate the overcurrent protection device should a ground fault occur.
If the grounded and ungrounded conductors are spliced in the box, so should the grounding conductor and it should be bonded to the box.
Not sure why this is, other than the fact that your removing insulation from a current carrying conductor in the Junction box whereas before it would have merely passed through the box undisturbed.
Maybe someone else can chime in on why the ground wire must be spliced and bonded when the grounded and ungrounded conductors are spliced. I dont fully understand this myself.