40A or 50A

[1793]

I was on a job today and as I was leaving the HO asked me to look at her free standing range. She told me that when she turns on the burners and the oven the breaker trips. I looked at the panel, outdoor FPE, and noticed that the range was on a 30A breaker with #10.

Just for kicks and giggles I put a meter on the circuit at the panel and turned on every burner and the oven. I read anywhere between 42 and 45A. The name plate says it's 12.5kW.

My question: How should I size the new wiring for this unit? I've looked at Table 220.55 and done the math but the meter readings tell me differently.

Could the current wire size, 10's, give me a higher reading?

Thanks

 

[don_resqcapt19]

On a resistive load, the smaller wire will give you a lower current, not a higher one.

 

[1793]

On a resistive load, the smaller wire will give you a lower current, not a higher one.

Thanks. It's amazing what you get confused over time.

 

[augie47]

You may notice that Note 4 of Table 250.55 allows you to use that Table for calculating the branch circuit load.
If I read it correctly, that would result in your branch circuit for a 12.5kw range to have a minimum rating of just over 8kw. With Romex that would require a #8 and allow a breaker of 40 amps. Anything less than that would not be Code compliant,

 

[1793]

You may notice that Note 4 of Table 250.55 allows you to use that Table for calculating the branch circuit load.
If I read it correctly, that would result in your branch circuit for a 12.5kw range to have a minimum rating of just over 8kw. With Romex that would require a #8 and allow a breaker of 40 amps. Anything less than that would not be Code compliant,

Should I be concerned that it was testing out higher than 40A and putting it on a 40A?

 

[augie47]

I see a lot of ranges of similar size operate on a 40 amp breaker. Keep in mind the Code is a minimum. With that size range if I was going to install a new circuit I would go to a #6 on a 50 amp but the customer is paying the bill.

 

[1793]

I see a lot of ranges of similar size operate on a 40 amp breaker. Keep in mind the Code is a minimum. With that size range if I was going to install a new circuit I would go to a #6 on a 50 amp but the customer is paying the bill.

I was leaning towards this set up. I just wanted to make sure I was not overlooking something on this install.

Thanks to all for your expertise.