Question about flexible cord ampacity

[danno1202]

Table 400.5 (A)(1) Gives the allowable ampacities for flexible cords. Is there, or was there ever a provision that allowed a cord to be reduced one size in certain situations? I definitely remember such a provision but can't seem to find anything of that sort now. Thank you.

 

[OldSparks]

I’ve never heard nor read that exeception. Maybe you are thinking of conductors in “free air”, such as an overhead span between two buildings.

It seems to me that with cable, because conductors are in very close physical proximity and heat is contained within two layers of insulation, one would error in the other direction - oversizing the cord.

 

[Jraef]

So maybe INDIRECTLY...

IF you have a 5 wire cord AND it is being used in a 3 phase Wye system (3 phases, a neutral and a ground), where the neutral conductor is only going to carry the unbalanced current from the other three phases, i.e. the load is always a true 3 phase load, then you do NOT need to count the 4th wire (neutral) as a "current carrying conductor", which would have triggered a de-rate to 80% of the stated ampacity. So basically in that circumstance, you CAN use that 5 wire cord at it's full rating.

 

[JFletcher]

I seem to recall a provision in chapter 4 for wiring lights with cable whips that allows for smaller than 14 gauge conductors if only feeding that one light.