electrcian

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Srice

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Hackensack N.J U.S.A
Can someone explain to me why an electric oven which spans 208- 240 volt single phase uses 13.4 kw at 240 volt and 10.1 kw at 208 volt . It would seem to be at odds with ohms law. In addition the manufactuer says at either kw the overcurrent is 40 amp. Am I wrong in calculating the amperage at 13,400 divided by 240 = 55 amps and 10000 divided by 208 = 48 amps. Thanks in advance.
 
The oven has a fixed (minimum) resistance of approximately 4.3 ohms.

At 240 volts, you get 240V / 4.3 ohms = 55.8A and 240V x 55.8A = ~13.8 kW.

At 208 volts you get 208V / 4.3 ohms = 48.4A and 208 * 48.4A = ~10.1 kW.
 
Congress repealed Ohms law because it was biased against the ignorant. :dunce: They didn't know what the law was about ( they never read those things ) but the knew they didn't like it ( no special interest money ).
 
Srice said:
40 amp breaker for both?
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Protects the #8 copper conductor feeding the range.


The range will never operate at 100% capacity or that 55 amp, at least not long enough to worry about.

I am surprised they didn't specify a 50 amp circuit for the range but you will have to take that up with the manufacturer.

I have seen a few ranges that did require a 50 amp circuit but very few.
 
Srice said:
Can someone explain to me why an electric oven which spans 208- 240 volt single phase uses 13.4 kw at 240 volt and 10.1 kw at 208 volt . It would seem to be at odds with ohms law. In addition the manufactuer says at either kw the overcurrent is 40 amp. Am I wrong in calculating the amperage at 13,400 divided by 240 = 55 amps and 10000 divided by 208 = 48 amps. Thanks in advance.
Click to expand...

As DFM stated your math was incorrect because you need to use the resistance with ohms law. Also as Jumper stated you can use T220.55 to apply a demand factor which may get you branch circuit down to 40 amps even if the the unit is 13.4 kw.
 
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