I've been away from the resi side of wiring for a while so I am a bit perplexed on the EE's call for 4#6's to a range recep. Is there now a nm cable with 4 #6's in it? Or is it still 3 #6's and a #10 ground? I don't know why the ground would need to be sized the same as the grounded or ungrounded conductors.