Fixed Electric Space-Heating Equipment

Article 424 covers fixed electric space heating — baseboard units, radiant heating cables embedded in floors and ceilings, unit heaters and duct heaters. It requires these loads to be treated as continuous when sizing conductors and overcurrent, sets clearances from combustible material and from receptacles above baseboard units, and governs the controls and thermostats that switch them.

Embedded heating cable gets special attention: spacing, splices and the prohibition on running cable under walls or through partitions where it can't dissipate heat. The whole article is about delivering heat where you want it while preventing the fire risk of a heat source next to wood, furniture or drapes.

When it applies

Article 424 covers fixed electric heat: baseboard units, radiant ceiling and floor cable, and heating panels. It sets branch-circuit sizing, clearances from furniture and finishes, and how controls and disconnects must be arranged.

Common mistakes

• Putting a receptacle directly above an electric baseboard so a lamp cord drapes onto the hot element.
• Sizing the circuit at the connected load instead of treating fixed heat as a continuous load at 125 percent.
• Covering radiant floor cable with a rug or furniture that traps heat and cooks the cable.

In the field

In a bedroom remodel I had to move a receptacle that sat right above a new baseboard heater. The homeowner did not realize a phone charger cord hanging down onto that element is a fire risk the Code specifically guards against. I relocated the outlet and sized the heater circuit for continuous load. Fixed heat runs for hours; treat it like the steady, serious load it is.