oven requirements

[JoeNorm]

I'm installing a stand alone single oven. They call it a 4.2KW unit and specify a 30amp breaker. The fixture whip(hard wired) is #12 stranded.

So I am thinking running #10 will be more than adequate but the manual calls for #8. Is there any justification for this?

Not only does it call out #8 but it says #8 solid wire, which I am not sure if I have ever even seen.

I normally defer to manufactures specs like I am supposed to but in this case I am questioning them. Thoughts?

 

[busman]

I'm installing a stand alone single oven. They call it a 4.2KW unit and specify a 30amp breaker. The fixture whip(hard wired) is #12 stranded.

So I am thinking running #10 will be more than adequate but the manual calls for #8. Is there any justification for this?

Not only does it call out #8 but it says #8 solid wire, which I am not sure if I have ever even seen.

I normally defer to manufactures specs like I am supposed to but in this case I am questioning them. Thoughts?

The only #8 solid I have ever seen was bare for grounding/bonding use.

Mark

 

[infinity]

Do you have a link to the instructions? The 30 amp circuit is fine. Why they would require #8's for a 30 amp circuit is beyond me. Also the #12 wire in the whip is fine because it typically is a much higher temperature rated wire than THHN and the manufacturer can use conductors smaller than those required by the NEC. Good luck trying to find a cable with #8 solid.

 

[Little Bill]

I don't get the 30A breaker. OP says 4.2KW and that would be 17.5A @240V. If it was 208V, that would only be 20.19A.

 

[LarryFine]

So I am thinking running #10 will be more than adequate but the manual calls for #8.

Tell the inspector you lost the manual.

 

[LarryFine]

If it was 208V, that would only be 20.19A.

True IF it was a unit built for the same power on the lower voltage; otherwise, the current would be lower.

 

[Little Bill]

True IF it was a unit built for the same power on the lower voltage; otherwise, the current would be lower.

I was thinking since the resistance (heating elements) were the same you would figure it the same.

 

[LarryFine]

I was thinking since the resistance (heating elements) were the same you would figure it the same.

To do that, determine the load's resistance (the constant), then calculate the new current (the result) on the new voltage (the variable).

Remember, a resistive load actually has a fixed resistance, not a fixed power. The rated power is a result of applying a certain voltage.

 

[busman]

To do that, determine the load's resistance (the constant), then calculate the new current (the result) on the new voltage (the variable).

Remember, a resistive load actually has a fixed resistance, not a fixed power. The rated power is a result of applying a certain voltage.

I'm not sure I would call a heating element a "fixed resistance" value. The resistance goes up as the heat goes up, just like a light bulb. Please tell me if I'm missing something, I probably am.

Mark

 

[qcroanoke]

I'm installing a stand alone single oven. They call it a 4.2KW unit and specify a 30amp breaker. The fixture whip(hard wired) is #12 stranded.

So I am thinking running #10 will be more than adequate but the manual calls for #8. Is there any justification for this?

Not only does it call out #8 but it says #8 solid wire, which I am not sure if I have ever even seen.

I normally defer to manufactures specs like I am supposed to but in this case I am questioning them. Thoughts?

Is there a UL label? 8 solid in romex or se I have never seen.

 

[hbiss]

Who makes this oven? Is it residential or commercial?

-Hal

 

[LarryFine]

I'm not sure I would call a heating element a "fixed resistance" value. The resistance goes up as the heat goes up, just like a light bulb. Please tell me if I'm missing something, I probably am.

Compared to cold, I'm sure you're right, but I doubt there's much difference between 240v and 208v.

 

[JoeNorm]

I actually cannot remember the brand right now. To be clear, I already ran #10 so I am choosing to ignore the specs.

I just thought I'd ask here to see if anyone has seen oddball requirements like that.

 

[drcampbell]

I'm not sure I would call a heating element a "fixed resistance" value. The resistance goes up as the heat goes up, just like a light bulb. Please tell me if I'm missing something, I probably am.

Mark

I think you meant "as the temperature goes up".
You're not missing anything about the physics; they're spot on. But it appears your editor was asleep at the switch.

 

[hillbilly1]

Probably Chinese made. I had an Italian engineer want 5/0 wire to a machine I was installing! Maybe they make 5/0 in Italy, but sure haven’t seen it here! LOL!

 

[busman]

I think you meant "as the temperature goes up".
You're not missing anything about the physics; they're spot on. But it appears your editor was asleep at the switch.

Yes. Meant Temperature. Thanks for the correction.

Mark

 

[tortuga]

#8 solid would be a code violation, at least in a raceway. 310.3(C)