Check my math but 220x220/9000 is not 6.4still_stirrin wrote: ↑Fri Jan 20, 2023 9:32 amYou’ve got this wrong.quadra wrote: ↑Fri Jan 20, 2023 3:26 am There are a bunch of things you really should change .. green is ground.
North American "220" is actually split phase 240 unless you have very poor power service. That is important because if you actually are dropping to 220 the current draw will increase from 37 to almost 41 Amps with a 9Kw load.
A 9kW (resistive) element will conduct (9000 / 240) = 40.9 amps with a 240 VAC supply rail. But, the current conducted is a function of the voltage, not the “power rating” of the element. The element is a resistor (maybe with a trace amount of inductance) and it is approximately 240 x 240 / 9000 = 6.4 ohms, and that is constant regardless of the voltage (at least until you burn up the resistor by applying a voltage exceeding the resistor’s rated voltage).
So, if the rail voltage is 220 VAC, then the current conducted is 220 / 6.4 = 34.4 amps. And the power dissipated is 220 x 34.4 x 34.4 = 7563 watts. So, the power is reduced because the voltage (the motive force for conduction) is less. And keep in mind that the element is rated for a supply voltage defined by the peak potential, not the RMS value.
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Actually, check your math too... 9000/240 is not 40.9
