Which parameter is crucial when measuring the load for show-window lighting?

When measuring the load for show-window lighting, the horizontal measurement of all sides is a critical parameter because it directly impacts how the lighting will illuminate the display and affect visibility from outside the window. This measurement helps determine the overall area that needs to be lit effectively and ensures that the light can cover the entire display appropriately.

Having accurate horizontal dimensions allows the electrician to assess how many fixtures are needed and their placement to achieve uniform lighting. It informs decisions related to fixture wattage and spacing to avoid dark spots or over-lit areas. Proper coverage will enhance the aesthetics of the merchandise displayed and attract customers by making the products more appealing.

Considering other factors such as the height of the window, angle of light distribution, or wattage of individual fixtures certainly play a role in lighting design, they do not provide the foundational spatial measurements necessary to accurately assess load requirements. Instead, these factors should be evaluated alongside the horizontal dimensions to create an effective and compliant lighting configuration for show-windows.