Kitchen Remodeling- Microwaves, Disposals, Insta-Hot and more oh my!

Yet there is many other areas of the code this installation can also fail.  (All the references I am using are from the 2014 NEC).

Very first piece of information is from Article 100- Definitions

So let the fun begin and let’s jump into some of the codes-

First up is the rules on SABC’s-

Article 210.11 Branch Circuits Required

(C) Dwelling Units.

(1) Small-Appliance Branch Circuits.

In addition to the number of branch circuits required by other parts of this section, two or more 20-ampere small-appliance branch circuits shall be provided for all receptacle outlets specified by 210.52(B).

Article 210.52 Dwelling Unit Receptacle Outlets

(B) Small Appliances.

(1) Receptacle Outlets Served.

In the kitchen, pantry, breakfast room, dining room, or similar area of a dwelling unit, the two or more 20-ampere small-appliance branch circuits required by 210.11(C)(1) shall serve all wall and floor receptacle outlets covered by 210.52(A), all countertop outlets covered by 210.52(C), and receptacle outlets for refrigeration equipment.

(2) No Other Outlets.

The two or more small-appliance branch circuits specified in 210.52(B)(1) shall have no other outlets.

Exception No. 1: A receptacle installed solely for the electrical supply to and support of an electric clock in any of the rooms specified in 210.52(B)(1).

Exception No. 2: Receptacles installed to provide power for supplemental equipment and lighting on gas-fired ranges, ovens, or counter-mounted cooking units.

From the NEC Hand Book-

“A minimum of two 20-ampere circuits is required for all receptacle outlets, including those for refrigeration equipment, in the kitchen/dining areas of a dwelling unit. The limited exceptions to 210.52(B)(2) keep loads for specific equipment to a minimum so that the majority of the circuit capacity is dedicated to supplying cord-and-plug-connected portable appliance loads.

Connecting fastened-in-place appliances, such as waste disposers or dishwashers, to these circuits reduces the capacity to supply the typical higher wattage portable appliances used at a kitchen counter, such as toasters, coffee makers, skillets, and mixers. The Code restricts the loads supplied by these receptacle circuits because the number of cord-and-plug-connected portable appliances used by occupants is generally undetermined.

No restriction is placed on the number of outlets connected to a general-lighting or small-appliance branch circuit. The minimum number of receptacle outlets in a room is determined by 210.52(A) based on the room perimeter and on 210.52(C) for counter spaces. Installing more than the required minimum number of receptacle outlets can also help reduce the need for extension cords and cords lying across counters.”

Now let’s move onto some other branch circuit requirements. Typical over the range Microwaves are rated at 1000W or better. So that equals 8.33+ amps on a 120v system.

Article 210.23 Permissible Loads, Multiple-Outlet Branch Circuits

In no case shall the load exceed the branch-circuit ampere rating. A branch circuit supplying two or more outlets or receptacles shall supply only the loads specified according to its size as specified in 210.23(A) through (D) and as summarized in 210.24 and Table 210.24.

(A) 15- and 20-Ampere Branch Circuits.

A 15- or 20-ampere branch circuit shall be permitted to supply lighting units or other utilization equipment, or a combination of both, and shall comply with 210.23(A)(1) and (A)(2).

Exception: The small-appliance branch circuits, laundry branch circuits, and bathroom branch circuits required in a dwelling unit(s) by 210.11(C)(1), (C)(2), and (C)(3) shall supply only the receptacle outlets specified in that section.

(1) Cord-and-Plug-Connected Equipment Not Fastened in Place.

The rating of any one cord-and-plug-connected utilization equipment not fastened in place shall not exceed 80 percent of the branch-circuit ampere rating.

(2) Utilization Equipment Fastened in Place.

The total rating of utilization equipment fastened in place, other than luminaires, shall not exceed 50 percent of the branch-circuit ampere rating where lighting units, cord-and-plug-connected utilization equipment not fastened in place, or both, are also supplied.

So from these code sections above depending on whether the appliance is fastened in place or not will change the allowable percentage the appliance load that can be on the circuit between 50% and 80% of that total allowable circuit load. (That was easy enough)

Then we have this tidbit that comes into play since the microwave also is functioning as a Range Hood.

Article 422.16 Flexible Cords

(B) Specific Appliances.

(4) Range Hoods.

Range hoods shall be permitted to be cord-and-plug-connected with a flexible cord identified as suitable for use on range hoods in the installation instructions of the appliance manufacturer, where all of the following conditions are met:

(1)The flexible cord is terminated with a grounding-type attachment plug.

Exception: A listed range hood distinctly marked to identify it as protected by a system of double insulation, or its equivalent, shall not be required to be terminated with a grounding-type attachment plug.

(2)The length of the cord is not less than 450 mm (18 in.) and not over 900 mm (36 in.).

(3)Receptacles are located to avoid physical damage to the flexible cord.

(4)The receptacle is accessible.

(5) The receptacle is supplied by an individual branch circuit.

So since the microwave is acting as a range hood it now needs to be on an individual branch circuit. So that right there takes care of that requirement.

So for the roundup and a few examples.

The rating of any one cord-and-plug-connected piece appliance/equipment, not fixed in place, must not exceed 80% of the branch circuit amp rating.

The maximum any cord-and-plug load on a “15 amp rated receptacle”, supplied from either a 15 or 20 amp branch circuit will be 12 amps (15 x 80%).  Now if you have a 20 amp rated receptacle and is being supplied by a 20 amp branch circuit your total load for a cord-and-plug equipment/appliance can go up to 16 amp (20 x 80%). As you can see here we now need to know what the actual rating of the receptacle is.

If you have the equipment that is fixed in place on a circuit that shares lighting or other receptacles that could have equipment plugged in that total rating for cord-and-plug-connected piece appliance/equipment now cannot exceed 50% of the branch circuit amp rating.

Example with our little microwave, it is a fixed installation and is plugged into a receptacle supplied by a 20-ampere, general purpose branch circuit, lets say from the front room. The circuit feeding the microwave receptacle also feeds other receptacles and other “utilization equipment”, such a lamp, not fastened in place will be plugged into those other receptacles.

Because this fastened-in-place equipment is now on a circuit with other equipment that is not fastened in place, the microwave cannot exceed 10 amperes (20amps x 50 %).

In this example it is most likely this circuit will be rated at 15 amps. Now the MIcrowave could not exceed 7.5 amperes (15 x 50 %). If the microwave was not fixed in place on the circuit, it could be rated up to 80 % of the circuit rating.

See how easy that was and why these type of installations really need to be performed by an electrician who knows the rules. It is of my opinion that just because it difficult does not make it right to do the wrong thing.

As a home inspector I think part of my job is to let my clients know what I see and provide that information, paint a picture. It would be wrong for me not to disclose this information if I know it?

“Knowledge has to be improved, challenged, and increased constantly, or it vanishes.”

Peter Drucker

If you find any errors or have additional information that would expand on any code, building standards or manufacture requirements please let me know.

NCW Home Inspections, LLC  is a Licensed Washington State Home Inspection service located in Wenatchee Washington serving Chelan County, Douglas County, Kittitas County, Okanogan County and Grant County Washington and the cities of Wenatchee, Leavenworth, Cashmere, Oroville, Cle Elum, East Wenatchee, Quincy and many more…  

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If you find any errors or have additional information that would expand on any code, building standards or manufacture requirements please let me know.