25 amp breaker with 20 amp receptacles

[ThinkingARB]

I have a requirement to place plug-in 1.08 kW, (115v) hotplates throughout a resturant. The challenge is to avoid adding another electrical panel and more breakers I hoping to place two plug-in hotplates on there own single, 120v/20 amp receptacle with those two single recepticles connected on the same 25 amp breaker.

So the question is can a 20 amp receptacle be placed on a 25 amp overcurrent protected circuit?

 

[charlie b]

I don't think so. Take a look at Table 210.21(B)(3). Your proposed configuration isn't included in that table, so I infer it would not be allowed.

Welcome to the forum.

 

[haskindm]

What size wire would you install on that 25-amp breaker? I agree with Charlie. Since you are contemplating a multi-outlet circuit 210.24 would apply. What you are suggesting is not one of the available choices. You will need to come up with another plan.

 

[petersonra]

It may be that the kW rating is stated at 125 V. 1.08 kW would be about 8.64 amps at 125 V.

My guess is that even if both were on simultaneously for an extended period of time, it would not trip a 20 A breaker, especially since you will have less current at 115V than at 125V.

 

[steve66]

I also don't see a problem with a 20 amp breaker. Wouldn't these hot plates have thermistors on them that turn the heat on & off?

 

[izak]

More Current.

More Current at 115 than at 125

not less

 

[crossman]

not if they are resistive heaters

 

[LarryFine]

More Current.

More Current at 115 than at 125

not less

This is a common error, because of the way we explain Ohm's and Watt's laws. For a given amount of power, it's true that voltage and current vary inversely. That takes making power a constant, and voltage a variable.

However, that's just math. You must remember what are and are not considered the variables in the real world. To keep power constant as voltage changes, you must change the impedance of the load as the voltage changes.

The equipment impedance and the system voltage are usually considered constants. But, when discussing a variable voltage and a constant impedance, current will change proportionately with voltage, not inversely.

 

[ThinkingARB]

Thank you all for the valuable feedback!

My original thought was to run 10 AWG to all the hotplates meeting the requirements of the 25A circuit. From there I would have multiple outlets of proper size to meet the needs of the individual loads but not requiring the special receptacals of a 30A circuit.

Table 210.21(B)(3) does give the example of placing 15A receptacles on a 20A circuit when multiple receptacles are used. While there is a little extrapolation required, placing multiple receptacles where each receptacle load was less than rated value and where total receptacle draw was less than the breaker, should be okay?

At this point asking a code offical to by into the concept might be more wishful thinking since following NEC is a less risky choice.

 

[petersonra]

More Current.

More Current at 115 than at 125

not less

The heaters are almost certainly resistive in nature. that means as the voltage goes down, the current will also go down.