Dedicated circuits

jea48, thanks for all you do here on these threads, it’s appreciated.

As an aside, we had a job 10 years ago with in-floor heat, continuous cable laid under stone tile. The largest zone was apparently a bit too big, on a 20A breaker, and pulling a consistent 17-18 amps. The breaker would hold it for hours, but then finally trip.

Thank you, @jea48 .

FWIW, what you did is electrically safe,... It just doesn’t meet code.

I am putting the 20A breakers back in tomorrow.  In the event of a catastrophe, even an unrelated catastrophe, I'd rather meet code and not be trying to argue with the insurance code about it.

@bigtwin 

Wow!! That's a 30 amp plug alright.   I'm confused by your comment. 

I've never seen an audio amplifier with a 30 amp plug on it before. 

. . . you see, my misunderstanding was that I was considering the outlet part of the Romex. In other words, since is legit to run heavier Romex in a circuit than what the breaker is rated for, I was thinking that the same would apply to the outlet. In other words, it would NOT be legit to have a 20A breaker for a circuit ran with 14 gauge Romex, but it would be legit to have 12-2 Romex with a 15A breaker, and therefore, I was thinking that as long as the other components of the circuit (Romex and outlets) were rated for more than the breaker, that would be safe and legit.

Thank you for clarifying for me what was wrong with that logic--safe, but not legit.

I think I know where the mistake in VA is coming from.  Too little understanding of the math around transformers.

For an ideal transformer (without losses) the VA on the input equals the VA on the output, however!! If the V on the input drops, V*A is less on input, therefore V*A is less on output.

Transformers are often used in voltage regulators, but they do their magic by altering the output taps.  Most linear gear is not this lucky, but most line level gear is well regulated so 20% voltage changes won't matter.  Amps are not so lucky.