Is there a minimum length for power cords?

"However, any length shorter than 1.8 meters (5.9 feet)will begin to degrade the effectiveness of the shielding and filtering capabilities"

Sounds plausible to the layman I guess. If it's true it would then depend on how badly your set-up needed the shielding and filtering to begin with. This has been discussed in a similar thread here recently
http://forum.audiogon.com/cgi-bin/fr.pl?fcabl&1396218203&&&/Power-cord-length-

I would be curious to hear what other power cord manufacturers have to say about this? Could be true for one company but necessarily all of them.

Another manufacturer says no less than 3 feet. And some cable companies say that less than 8 feet is not ideal for speaker cables.

I think the manufacturers just want to sell us more wire.

Who's cables are we talking about here? I don't think anyone mentioned any brands up to this point. I'm guessing that the OP is referring to Shunyata, but it would be helpful to know for sure because I'd like to see if other manufactures give the same reason for the cables sounding better at a minimum length.