Dwelling unit circuits

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iwire

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Massachusetts
That's a good point on NEC 220.60, I think that non coincident is being miss-applied.

Well I do not see a distinction in the NEC.

If only one of two loads can run at one time you only have to worry about the heaviest of them.

Do not misunderstand me, I think this is a pretty poor design but I do not see a safety issue or a glaring NEC violation.
 

Volta

Senior Member
Location
Columbus, Ohio
Well I do not see a distinction in the NEC.

If only one of two loads can run at one time you only have to worry about the heaviest of them.
...

You don't see a distintion between Part II and Part III of Article 220?

Part II is for branch-circuit calculations.
Part III is for Feeder and Service Load Calculations
Noncoincident Loads is Section 220.60, and the section ends "for calculating the total load of a feeder or service".

In practice you are right, of course. The load will only be the largest of the two, but that isn't how the branch-circuit is calculated, unless another section allows it.
 

Volta

Senior Member
Location
Columbus, Ohio
I do not see anything in the NEC that requires me to calculate a circuit based on what is not connected to it.

Hmm, maybe not. But very often a room full of lights is not connected to its circuit, yet I bet we add the load.

I will allow though that the SPDT or DPDT is different situation.
 

iwire

Moderator
Staff member
Location
Massachusetts
Hmm, maybe not. But very often a room full of lights is not connected to its circuit, yet I bet we add the load.

I will allow though that the SPDT or DPDT is different situation.

Those were my thoughts as well, any switch disconnects the equipment from the circuit but there seems to me to be a difference with a selector type switch.

As much as I agree the situation the OP describes is not what the NEC intends I do not see a safety issue.
 

Volta

Senior Member
Location
Columbus, Ohio
Those were my thoughts as well, any switch disconnects the equipment from the circuit but there seems to me to be a difference with a selector type switch.

As much as I agree the situation the OP describes is not what the NEC intends I do not see a safety issue.

Well, besides the food safety issue, I'm sure. ;):cool:
 

bealfi

Member
I believe they're trying to designate the refrigerator as one of the kitchen circuits, and the microwave as the other. In this case, they're switching between the two with one home run.
 

Volta

Senior Member
Location
Columbus, Ohio
I believe they're trying to designate the refrigerator as one of the kitchen circuits, and the microwave as the other. In this case, they're switching between the two with one home run.
Guess they figure that NEC 210.11 is satisfied with the switching.
There need to be two or more 20 amp branch-circuits. Can't get around that requirement. If only one 'home run', it can be a 12/3 (multi-wire) circuit, fed from two handle-tied breaker poles. Or it can be two 12/2 circuits, fed from two breaker poles. But it can't be a single circuit to feed the common of a double-throw switch.

Switching one circuit between two loads is separate concern. I doubt the health department would be fond of a part-time foor refrigeration system.

Will the microwave be fastened in-place?
 

russ

Senior Member
Location
Burbank IL
I guess if you can't find a code prohibiting this, the least you could do is to make sure the selector switch has a horsepower rating that meets the code requirements in 440 part II.
 
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