derating ground and egc

[Towzzer]

I noticed on some of the range cords being offered at various location that they are composed of 6/2 + 8/2, Does this mean , assuming I ran a emt/pvc , I could derate both the ground and egc

 

[RUWired]

Towzzer,,Only existing circuits suppling ranges/dryers, and also cooktops,are still allowed to use the 3 wire cord sets. If you are running a new circuit, you must run a 4-wire circuit.A full size ground is needed.(#10 awg for 40/60 amp circuits).As far as derating the grounded conductor, i believe you could only do that for the 3-wire circuits.Check article 210.19 (3) exception 2 if this applies to you.
Rick

 

[Towzzer]

I was referring to 4 wire cord set it's 6,6,8,8 inside

 

[suemarkp]

I believe ranges and clothes dryers that are 120/240 may have the neutral ampacity assumed to be 70% of the ungrounded ampacity.