fixed in place appliance demand

Merry Christmas
In the past, if I have had a microwave "fixed in place" above my wall mounted oven, it could be counted as one of the four appliances that would apply to the calculation that allowed a 75% demand factor to be applied if there were four or more appliances that were "fixed in place". I see in the new code book the explanatory print makes it a point to exclude "(1) Household electric cooking equipment that is fastened in place". Is the microwave a cooking appliance, or does that terminology only apply to what could be considered a range? Can the microwave still be counted as one of the fixed in place appliances, or does it need to be treated as cooking equipment and added to the calculation, based on the size (wattage) of the microwave?
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
The UL Guide Information for [Heaters and Heating Equipment] Microwave Cooking Appliances (KQSQ) says :
This category covers cooking equipment incorporating one or more microwave generators operating in the normal ISM bands of 915 + or - 25 and 2450 + or - 50 MHz. This equipment includes portable and stationary microwave cooking appliances employing resistive-type heating elements for baking, broiling, browning, convection cooking, or similar operations.
The code does not give a lot of guidance and the substantiation for the 2020 change in 220.53 looks like it was intended to cover electric cook tops as those are not ranges and were not covered by the 2017 code language. Nothing in the PIs, PCs, substantiations or panel statements mentioned microwaves.

However the words that are used in the 2020 code, "Household electric cooking equipment that is fastened in place", include microwave ovens that are fastened in place based on the product listing standard.
 

JoeStillman

Senior Member
Location
West Chester, PA
It looks like the article was improved so that the list of exclusions is set apart instead of buried in the middle of the paragraph. Notice that all of the exclusions are subject to demand factors of other articles;
  1. Cooking appliances; 220.55
  2. Dryers; 220.54
  3. Space Heating; 220.51 (100% demand factor except for non-coincidence)
  4. Air Conditioning; 220.82(C)
This just keeps us from double-dipping in the demand-factor salsa.

It's hard for me to imagine that, where microwaves were once allowed a 75% demand, now they are not, even though not mentioned explicitly. Also, it's a rare microwave that is big enough to count on table 220.55 (1750W).
 
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