Hi all,
This is a code question more than anything, but I thought it might be worth looking at.
I recently had a 240V electrical heating circuit added. #12 wire, 20A breaker. Max load is 3840W, but I want to drive 4500W. Unfortunately, 25A breakers aren't available for my panel (this would fix the problem) and I have no additional circuits left in my panel.
One other solution is to use 30A breakers and switch to #10 wire. Problem is that one heater was already in-place (and on a different floor) so I'd have to demolish the house to re-wire it. Is it acceptable to run #10 wire from the panel to the first thermostat (3000W), and keep the existing #12 wire for the remaining 1500W (which is branched from the first thermostat)?
Under normal conditions, current will never exceed wire maximums. However, if the 1500W heater had a fault, current through that section could potentially exceed the #12 capacity (30A) before tripping. Doesn't sound safe to me, but I wonder if there is anything in the code that would allow it.
FWIW, I have an alternate solution that will balance loads between heating circuits..it just isn't pretty because I need to create (and maintain access to) a junction in an existing circuit.