Hi Diver
iwire, A simple case is when you run conductors over a roof or attic where the ambient temperature can reach high levels. Unless the conductors are sized with regards to VD, this will cause a large VD that will start the insulation degradation process that will lead to a fire.
Diver I mean no disrespect, however I personally do not believe your above statement is true. If the circuit has the NEC required overcurrent protection that conductor in the attic will never become hot enough to start a fire or damage the insulation assuming you considered the proper ambient when selecting the conductor as required by the NEC.
99% of the time reduced voltage at the load will result in reduced current used by the load.
In the few cases that a load may draw more current with less voltage (say a motor) the motor overload protection will open before damaging the conductors.
Now don't get me wrong, I run a lot of 10 AWG for 20 amp circuits, I don't like the idea of my money being wasted heating undersized conductors.
![[Linked Image]](https://www.electrical-contractor.net/ubb/smile.gif)
That said I do not believe VD is a safety issue as long as the rest of the NEC is applied correctly.
