Short answer: Article 424 covers fixed electric space heating, such as baseboard heaters, wall heaters, radiant ceiling cable and duct heaters. Fixed space heating is treated as a continuous load, so the branch circuit conductors and overcurrent device are sized at no less than 125% of the total heating load. Each heater needs a disconnecting means, and a thermostat can serve as that disconnect only under specific conditions. Article 426 covers fixed outdoor deicing and snow-melting equipment, which generally needs ground-fault protection of equipment.
PSI lists air conditioning, refrigeration and heating among the topics in the Equipment and Devices subject area of the Texas Journeyman exam: 10 scored NEC Knowledge questions and 2 scored Calculations questions. PSI does not say how many cover electric heating alone. The Texas Journeyman Practice Pack has 1,000 original questions and 10 timed mock exams in the real two-part format, with step-by-step solutions for every calculation. Try free practice questions without signing up. Get the full pack for US$39 with one payment.
Tsai Electro is an independent learning site. Not affiliated with TDLR, PSI or NFPA. We explain the ideas in our own words and do not reproduce NEC text. Check every rule and table value in your own 2026 NEC, follow the heater manufacturer’s instructions, and follow your supervisor and the local inspector.
Where heating rules live
| Equipment | Where to look |
|---|---|
| Baseboard, wall, ceiling and radiant space heaters, duct heaters, unit heaters | Article 424 |
| Heat pumps and air conditioners with heating elements | Article 440, together with 424 where it applies |
| Portable heaters plugged into receptacles | Article 422 |
| Snow-melting and deicing cable in driveways, ramps, roofs and gutters | Article 426 |
| Heat tracing on pipes and vessels | Article 427 |
Branch circuits: the 125% rule
Fixed electric space heating, including any motors that are part of the equipment, is considered a continuous load (NEC 424.5). The branch circuit conductors and the overcurrent device must be rated at no less than 125% of the total load of the heaters and motors. Then the ampacity of the conductors and the rating of the breaker are chosen from the standard sizes, with the small-conductor limits of 240.4(D) still applying.
Two more branch circuit points:
- Heaters only, or heaters with other loads. A branch circuit that supplies fixed space heating may also supply other loads only under the conditions the code sets. Most baseboard circuits are dedicated.
- Large resistance heaters. Resistance heating elements in larger equipment are subdivided, with each subdivided load protected at no more than the limit in Article 424 (NEC 424.22).
Baseboard heaters and receptacles
Factory-installed receptacle outlets in a permanently installed baseboard heater can count toward the required wall receptacle outlets, but they must not be connected to the heater circuits (NEC 424.10). Many listed baseboard heaters come with instructions that do not allow installation below a wall receptacle, because cords hanging over the heater can be damaged by the heat, and the NEC requires listed equipment to be installed according to those instructions. Read the heater instructions before you set it under an outlet.
Disconnects and thermostats
Each piece of fixed electric space heating needs a means to disconnect the heater, any motor controllers and supplementary overcurrent devices from all ungrounded conductors. The disconnect is generally within sight of the equipment or capable of being locked in the open position.
A thermostat can serve as the disconnecting means only where it has a marked off position, directly opens all ungrounded conductors when manually placed in that position, cannot energize the circuit automatically from there, and is located and accessible as the code requires. A typical single-pole line-voltage thermostat on a 240 V heater opens only one conductor, so it does not qualify as the disconnect.
Outdoor deicing and snow-melting: Article 426
Article 426 covers heating cable and panels installed outdoors to melt snow and ice on driveways, walkways, ramps, roofs and gutters.
- Ground-fault protection of equipment. Fixed outdoor electric deicing and snow-melting equipment generally needs ground-fault protection of equipment (NEC 426.28). The section has a narrow exception for some mineral-insulated cable embedded in concrete.
- Continuous load. As with space heating, size the branch circuit at 125% of the load.
- Disconnect. The equipment needs a means to disconnect all ungrounded conductors at the same time. A branch circuit switch or breaker can serve as that disconnect when it meets the conditions in Article 426.
Worked example: three baseboard heaters on one circuit
A bedroom gets three 1,500 W, 240 V baseboard heaters on one dedicated branch circuit. Assume copper conductors, 60°C terminals and no correction or adjustment factors. Size the breaker and conductors.
- Total load. 3 × 1,500 W = 4,500 W.
- Current. 4,500 W ÷ 240 V = 18.75 A.
- 125%. 18.75 A × 1.25 = 23.44 A. The circuit must be rated at least 23.44 A.
- Breaker. The next standard size above 23.4 A is 25 A.
- Conductor. 12 AWG copper is limited to 20 A overcurrent protection by 240.4(D), so it cannot go on a 25 A breaker. 10 AWG copper, 30 A in the 60°C column of Table 310.16, works.
- Check. 25 A is at least 23.44 A, and 30 A conductor ampacity is at least 25 A.
A fourth heater would bring the load to 6,000 W, 25 A, and 31.25 A at 125%. A branch circuit supplying two or more outlets for fixed space heating is limited to 30 A, so split the heaters onto a second circuit instead of upsizing this one.
Check yourself
- At what percentage of the heating load are the branch circuit conductors and breaker sized for fixed space heating? No less than 125%.
- Can a single-pole line-voltage thermostat on a 240 V heater serve as the disconnect? No. A thermostat must have a marked off position and open all ungrounded conductors.
- What extra protection does fixed outdoor snow-melting cable generally need? Ground-fault protection of equipment.
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Find Articles 424 and 426 faster on exam day
NFPA 70, National Electrical Code, 2026 Edition (softcover). Highlight the branch circuit sizing and disconnect rules in 424 and the ground-fault protection rule in 426, since heating questions often mix code lookup and a 125% calculation. The Texas exam is open book. PSI allows a soft-bound NEC with highlighting, underlining and notes made in advance. Loose-leaf, spiral-bound and ring-bound copies are not allowed, and only permanent index tabs made or supplied by the NEC publisher are permitted; homemade and third-party tabs are not.
FAQ
What size breaker do I need for baseboard heaters?
Add the wattage of all heaters on the circuit, divide by the voltage, and multiply by 1.25. Pick the next standard breaker size at or above that number and a conductor rated for the breaker. Three 1,500 W heaters at 240 V come to 23.44 A, so a 25 A breaker with 10 AWG copper.
Can a baseboard heater go under a receptacle?
Many listed baseboard heaters have instructions that do not allow installation below a wall receptacle, because cords can hang over the heater, and those instructions must be followed. Check the heater instructions before you plan the layout.
Does snow-melting cable need GFCI?
Article 426 generally requires ground-fault protection of equipment (GFPE), which is not the same as the GFCI protection used for people. An exception covers mineral-insulated, metal-sheathed cable embedded in a noncombustible medium.
Is electric heating on the Texas Journeyman exam?
PSI lists air conditioning, refrigeration and heating in the Equipment and Devices subject area, which has 10 scored NEC Knowledge questions and 2 scored Calculations questions. PSI does not say how many cover electric heating alone.
Sources checked October 2026
- PSI Candidate Information Bulletin, Texas electrician examinations (updated September 15, 2026): https://test-takers.psiexams.com/api/content/bulletin/1682
- NFPA 70, National Electrical Code, 2026 Edition, Articles 240, 310, 424 and 426
