A Show Window is the area at the front of a store for displaying merchandise. The definition in NEC^® Article 100 makes it clear that the show window also includes the area above the door.

The reason this is important is because the NEC^® has specific rules for show windows:

• Section 210.62 requires at least one 125-volt, single-phase, 15- or 20-amp receptacle outlet to be installed within 18 in. of the top of a show window.
• Section 220.14(G) requires an allowance of 200 volt-amperes per linear foot of show window to be used when calculating the branch circuit load for the show window.
• Section 220.46(A) requires an allowance of 200 volt-amperes per linear foot of show window to be used when determining the overall load from the show window circuits on the feeder or service.

Here is an example using the language above:

A group M (mercantile) occupancy has 46 linear feet of show window including the window area above the main entry door. This area will be using 20 ampere, 120-volt branch circuits to supply the receptacles serving the show window area.

To calculate the branch circuit load for the show window, multiply 200 VA by the length of the show window. 200 VA X 46 = 9200 VA. Now find the current by dividing 9200 VA by the circuit voltage of 120 volts. 9200 VA ÷ 120 volts = 76.66 amps or 77 amps.

Below is a preview of the NEC^®. See the actual NEC^® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to NFPA 70.

Code Language:

Article 100 Definitions:

Show Window:  Any window, including windows above doors, used or designed to be used for the display of goods or advertising material, whether it is fully or partly enclosed or entirely open at the rear and whether or not it has a platform raised higher than the street floor level.