What is a characteristic of wall receptacles besides height placement?

The correct choice emphasizes specific regulations related to wall receptacles in kitchens. Wall receptacles must be installed strategically, particularly in areas where food preparation occurs. The National Electrical Code (NEC) outlines that receptacles need to be placed above kitchen countertops to ensure accessibility for appliances and devices, which are often used in cooking and food preparation.

This characteristic highlights the functional requirement for power supply in kitchens rather than a prohibition against their installation in these spaces. Thus, having receptacles placed above kitchen counters is crucial for practicality and safety in culinary environments.

The other options suggest various features or rules that do not align with electrical installation guidelines or common practices. For instance, receptacles can be installed at various heights for accessibility, but they are not restricted solely to pairs or limited to lighting purposes.