DIY Oven Build - Amperage Questions

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DIY Oven Build - Amperage Questions

Post by Beej54 »

Hello All!

I have been powder coating for a few years and finally going to build a slightly bigger oven than a regular home unit now I have moved into a place with a bigger garage.

Now my question is (and I had a search but couldn't find an exact answer to this), I had a 50 Amp service at my old place, but this new one was only wired in the garage for 30 Amp. After receiving an estimate for the replacement, it got me thinking about how I can make the 30A work... when I realized the technical specs for the oven I bought to harvest parts list the Circuit Breaker as 30A! The unit is a Bosch Wall Oven (HBL5451UC) so no hot plates etc, 6,325 W / 240 V.

Would I be correct in assuming this will in fact work on the installed 30A service correctly? I can wire things just fine as the "mechanical aspect" of these tasks is very straightforward for me, but understanding the math behind the draw and safety limits/ headroom on electrical systems is a bit foreign to me.

Any help or clarification on this would greatly appreciated!
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Re: DIY Oven Build - Amperage Questions

Post by rdj357 »

Hmm - a circuit breaker is typically made to carry 80% of its load rating continuously. For a 30 amp breaker that would be 24 amps. It will be close and will possibly work depending on what your actual supply voltage at the new place. If it is a full 240v then it would draw 26.4 amps so depending on how long the elements stayed on continuously, would likely cause the breaker to get too hot and trip. If it’s closer to 220v and the wattage rating you posted is the 240v rating then the draw on 220v would be about 24.2 and would likely be just fine.

Check your voltage at the new place and divide it by the resistance of the elements to get the amperage. Based on what you said, I would expect resistance to be about 9.09 ohms but can’t hurt to double check. Know that the lower the voltage, the lower the actual wattage you’ll get in the oven - at that 220v guess, you’d be getting 5324 watts.
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Re: DIY Oven Build - Amperage Questions

Post by acourtjester »

If you stay with the parts you scrounged from the Bosch unit you should be fine. It sounds like a single element or only bake or broil but not both at the same time. That would limit the current draw on the breaker, it will pull full power until set temps are reached then a coasting draw to maintain set temps. The DIY oven I built has 2 large and 2 small top burner elements, after suing I dropped back to only 2 large and it gets to 400 degree fine.
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oven inside A.jpg

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