Hi Diver,
To my knowledge there is no EWT rule that wave C must be at least equal in length to wave A.
However, it does appear to be more often the case that wave C meets either the 100% extension of A or the 161.8% extension. For example, during a 61.8% retrace I quite often see a bounce off the 38.2% Fib up to the 23.6% Fib before the move down to the 61.8% one. This would make C = A in length.
If you're still looking at the move up from March 2009 lows as corrective then I think it counts far better as a double three. I'll post a count on that later...
