Where you place an electric baseboard heater is important for the heater's effectiveness and for safety. There are no universal electrical code rules about where to install baseboard heaters, so the best source to follow is the heater manufacturer's installation instructions. Different heater styles and models may have different spacing requirements; for example, some heaters run hotter than others and may need extra clearance. That's why it is critical to follow the instructions for your heater model.
That said, there are some general guidelines for positioning standard electric baseboard heaters, as well as some basic safety precautions.
Space Between a Baseboard Heater and the Floor
Many baseboard heaters can be installed directly on the floor without impeding airflow through the bottom of the heater. Heater units typically have a guard that prevents the air intake area from touching the floor. This design allows you to install the heater so it replaces a portion of the baseboard trim. In this case, you would run your baseboard up to the sides of the heater.
The common exception to this guideline is thick carpeting: If the carpet pile is tall enough that it might cover the air opening, the heater should be installed above the carpet.
Baseboard Heater Height
Heater manufacturers typically do not specify a maximum installation height, but most standard heaters provide the best performance when they are placed close to the floor. This is because hot air rises and cold air drops. Baseboard heaters heat the air above them, not below.
No matter what height you install a heater, you must follow the manufacturer's clearance requirements. Most baseboard heaters need at least 12 inches between the heater unit and any combustible material, such as drapes or furniture.
Space in Front of Baseboard Heaters
Baseboard heaters typically need at least 12 inches of space in front of the heater. You can place a couch or chair in front of a heater, but it must be at least a foot away. Placing furniture closer than that creates a potential fire hazard, and it can greatly diminish the heater's performance by restricting airflow to and from the heater. Note that this minimum applies to standard electric baseboard heaters. Heaters with fans need much more clearance—typically 3 feet or more.
When installing a baseboard heater near a door, make sure the heater cannot be blocked by the door when it is fully open. A door that comes within 12 inches in front of a heater is a fire hazard, just like furniture that is too close to a heater.
Baseboard Heater Side Clearance
Drapes, furniture, and other combustible materials should be at least 6 inches away from each side of a baseboard heater. As noted, most baseboard heaters are designed so that their ends can touch baseboard wall trim, but this applies only to the very ends of the heater unit. Anything placed to the side of the heater, or above and to the side, should be at least 6 inches away.
Baseboard Heaters and Electrical Outlets
Installing baseboard heaters under electrical outlets (receptacles) is a common point of discussion and confusion. Electrical codes typically do not prohibit installing heaters below wall outlets, but most heater manufacturers recommend against it. The concern is that a cord plugged into the outlet will likely drape down onto the heater. This could potentially melt the cord's plastic insulation, creating a serious shock and fire hazard.
The safest approach is to avoid installing heaters under outlets. It's okay for heaters to be next to outlets. The National Electrical Code (NEC) requires a wall outlet every 12 feet along walls; if an outlet is required where you'd like to install a heater, you may be allowed to use a heater with an integrated electrical outlet to meet the NEC outlet requirement.