All modern extension cords I've seen are rated 1250W or more. A 350W (hell even some of the early beasts that drew 415W) TV ain't even half way to the max rating of the cord....Most extension cords have much more copper in them per foot than the set's original cords (which most here use when not damaged) so I'd be more worried about the set than the extension cord....
IIRC it was miniman who accurately said that if you run multiple sets at the same time it will often shave a good number of volts off the line....Could not agree more!
Zeno if you've lit your smokes off a red hot part, your the man!....Closest thing I've done is to take a plasma speaker made form an old SS flyback a 555 and a power FET and lite a cig.....I might have been playing Boston's "Smokin' " on the arc when I did.
If my plasma speaker ever goes beyond a breadboarded toy I'll have to put some metal studs in my pipe so I can add lighter functionality to it.