Portable space heaters are common in facilities during cold weather, and they are a significant fire risk when used improperly. According to the National Fire Protection Association (NFPA), space heaters accounted for about one-third of U.S. home heating equipment fires from 2016 to 2020, but nearly nine out of 10 of the deaths [1]. Fires in which a heat source was too close to combustible materials caused the largest share of home heating fire deaths [1].

 

These figures come from residential fires, but the same hazards exist in facilities, where corrugated packaging, pallets, and other combustible materials are often stored near workstations. This guide covers the fire code and Occupational Safety and Health Administration (OSHA) requirements for portable space heaters, safe placement and electrical practices, and the use and maintenance of permanently installed unit heaters.

 

Fire Code Requirements for Portable Space Heaters

 

Portable electric space heaters are permitted where allowed by the applicable fire code. Under the 2018 IFC, heaters used in Group I-2 occupancies and ambulatory care facilities are limited to models with heating elements that cannot exceed 212°F (100°C), and may be used only in non-sleeping staff and employee areas (Section 604.10.5):

 

 

"Listed and labeled" means a nationally recognized testing laboratory (NRTL), such as UL or Intertek, has tested the heater to a safety standard and marked it accordingly [3]. Portable electric heaters are typically listed to UL 1278, the safety standard for movable and wall- or ceiling-hung electric room heaters. Because the code requires a direct connection to an approved receptacle, power strips and relocatable power taps are not permitted, either.

 

OSHA Requirements

 

OSHA does not have a standard specific to portable space heaters. Two requirements apply instead:

 

• The General Duty Clause. Section 5(a)(1) of the Occupational Safety and Health Act requires employers to provide a workplace free from recognized hazards that are causing or are likely to cause death or serious physical harm.
• OSHA's electrical standard for general industry (29 CFR 1910.303(b)(2)). This standard requires listed or labeled equipment to be installed and used in accordance with the instructions included in its listing or labeling. Most portable heater instructions prohibit extension cords and specify minimum clearances, so using a heater contrary to those instructions conflicts with this requirement.

 

These obligations rest with the employer, and they apply to every heater used in the workplace, including heaters employees bring from home.

 

Where to Place a Portable Space Heater

 

Clearance From Combustibles

 

Maintain at least 3 feet of clearance in every direction between a running heater and anything that can burn. In a facility, that includes corrugated boxes, packaging, shrink wrap, pallets, rags and shop towels, paper records, and clothing.

 

Walkways and Exits

 

Keep heaters and their cords out of walkways, aisles, forklift and pallet jack paths, doorways, and exit routes, where they create trip hazards and can obstruct an evacuation. If an area needs heat but has no safe location for a portable heater, a permanently installed unit heater is the appropriate solution.

 

Wet and Washdown Areas

 

Do not use portable electric heaters in areas that are wet or may become wet, such as wash bays, areas near eyewash stations, dock areas exposed to weather, and spaces cleaned by hose. Water creates a risk of electric shock and short circuits. For damp or washdown environments, specify a unit heater rated for those conditions.

 

Storage Areas

 

Keep portable heaters out of storage rooms. Material in these areas is moved and restocked frequently, which makes the required clearance difficult to maintain, and storage rooms are often unoccupied for long periods.

 

Electrical Load and Cord Safety

 

A 1,500-watt heater, the maximum for most plug-in units, draws 12.5 amps at 120 volts. That uses most of the capacity of a standard 15-amp circuit. Two such heaters on one circuit draw about 25 amps. The circuit breaker should trip, but overloaded circuits and loose or damaged connections can overheat before it does.

 

• Plug heaters directly into a wall receptacle. Do not use extension cords, power strips, or relocatable power taps.
• Give each heater its own circuit when possible. Do not share a circuit with other high-draw equipment, such as microwaves, coffee makers, or portable air compressors. If no receptacle is in a suitable location, have a qualified electrician install one rather than using a longer cord.
• Inspect the cord and plug before each use. Remove the heater from service if the cord is frayed, cracked, spliced, or pinched, or if the plug shows scorching or discoloration. A plug or receptacle that is hot to the touch indicates a problem; stop using the heater and have the receptacle inspected.
• Select heaters with factory cords long enough to reach the intended receptacle.

 

Daily Practices for Safe Use

 

Include these practices in a written heater policy:

 

1. Require approval before a portable heater is used. An approval step confirms each heater meets the policy and records where every unit is located.
2. Purchase heaters with automatic tip-over and overheat shutoff, and treat both as minimum requirements.
3. Confirm each heater is listed and labeled. Remove any heater with missing, broken, or damaged parts.
4. Turn heaters off and unplug them at the end of each shift. Leaving a heater on standby or a low setting is not sufficient.
5. Do not operate heaters in unoccupied areas.
6. Include heaters in routine safety inspections. Check clearance, cord condition, placement, and guards.
7. Keep a portable fire extinguisher suitable for the area accessible and inspect it monthly as required by OSHA's portable fire extinguisher standard (29 CFR 1910.157) [5].
8. Apply the policy consistently and remove heaters that do not comply.

 

Electric Unit Heaters

 

When a space regularly needs supplemental heat, a permanently installed electric unit heater is often a safer long-term solution than portable heaters. An electric unit heater is hard-wired to a dedicated circuit and mounted on a wall or suspended from the ceiling.

 

Because it has no cord and no floor footprint, a unit heater eliminates extension cord use, cord damage, overloaded receptacles, and trip hazards. Mounting it above the work area also keeps it out of walkways and away from most foot and equipment traffic.

 

Convection and Infrared Heaters

 

Convection unit heaters use a fan to move air across a heating element and warm the air in a space. Infrared, or radiant, heaters warm people and objects in their path directly rather than heating the surrounding air. That makes infrared heaters effective in high-ceiling areas, loading docks, and other spaces where heated air rises or escapes quickly. Both types have required clearances.

 

Placement and Clearances

 

Each unit heater has required clearances listed on its data plate and in the manufacturer's installation instructions. These include minimum distances to combustible materials, minimum mounting height, and space for service access. The requirements are specific to each model and must be followed under 29 CFR 1910.303(b)(2).

 

Mounting a heater does not prevent material from being stored within its clearance zone. Mark the clearance area on the floor or racking so it stays visible to employees putting away stock and include it in routine inspections. Position heaters so their discharge air is not directed at stored material.

 

In high-ceiling spaces, warm air collects near the ceiling. Circulation fans move that air back down to the work area, which improves comfort and reduces demand for portable heaters.

 

Maintenance

 

Dust can accumulate on heating elements, inside cabinets, and on fan blades, creating a potential fire hazard. Schedule maintenance before each heating season and at the intervals specified by the manufacturer.

 

Before cleaning or servicing, disconnect power, allow the heater to cool, and follow applicable lockout/tagout procedures. Assign electrical inspections and safety-control testing to qualified personnel.

 

Maintenance should include:

 

• Cleaning the cabinet, heating elements, and fan according to manufacturer instructions.
• Inspecting for corrosion, damaged wiring, and loose electrical connections.
• Testing the thermostat and high-limit safety switch using manufacturer procedures.
• Confirming guards are secure and in good condition.
• Verifying that required clearances remain unobstructed.

 

Record maintenance dates, findings, and corrective actions in the preventive maintenance schedule.

 

Fuel-Fired Heaters

 

Gas, propane, and other fuel-fired heaters have additional requirements for combustion air, venting, fuel storage, and carbon monoxide. Consult a licensed professional and the manufacturer's instructions before installing or using them.

 

Choosing the Right Heater

 

If employees regularly bring in portable heaters, the area is likely underheated. The right permanent heater depends on the size of the space, how it is used, the available power or fuel, whether heat is primary or supplemental, and how the unit will be mounted. Global Industrial's guide to choosing the best heater for your facility covers heater types, BTU sizing, and fuel options in detail.

 

Equipment for Safe Facility Heating

 

 

Global Industrial supplies facility heating equipment and the safety products that support it. We can supply that.®

 

Frequently Asked Questions

 

Are space heaters safe to use at work?

Yes, when used correctly. A heater should be listed and labeled, in good condition, plugged directly into a wall receptacle, kept at least 3 feet from combustible materials, and turned off when the area is unoccupied. Damaged or defective heaters should be removed from service.

 

Can a space heater be plugged into an extension cord or power strip?

No. The IFC requires portable electric heaters to be plugged directly into an approved receptacle and prohibits extension cords [2]. Heaters draw high current for long periods, which can overheat cords, power strips, and their connections.

 

Does OSHA allow space heaters in the workplace?

Yes. OSHA does not prohibit them and has no standard specific to them. Employers must address heater hazards under the General Duty Clause and must use listed equipment according to its instructions under 29 CFR 1910.303(b)(2).

 

Is a unit heater safer than a portable space heater?

Generally, yes. A hard-wired, mounted unit heater eliminates extension cords, cord damage, overloaded receptacles, and trip hazards. It still requires the clearances listed on its data plate, along with regular cleaning and inspection.

 

References

 

1. Campbell, R. (2022, December). Home heating fires. National Fire Protection Association. https://www.nfpa.org/education-and-research/research/nfpa-research/fire-statistical-reports/heating-equipment
2. International Code Council. (2017). 2018 International Fire Code: Chapter 6—Building services and systems, Section 604.10, Portable electric space heaters. https://codes.iccsafe.org/content/IFC2018/chapter-6-building-services-and-systems.
3. Occupational Safety and Health Administration. (n.d.). OSHA's Nationally Recognized Testing Laboratory (NRTL) program. U.S. Department of Labor. https://www.osha.gov/nationally-recognized-testing-laboratory-program
4. General, 29 C.F.R. § 1910.303 (2026). https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.303
5. Portable fire extinguishers, 29 C.F.R. § 1910.157 (2026). https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.157
6. Occupational Safety and Health Act of 1970, 29 U.S.C. § 654 (1970). https://www.osha.gov/laws-regs/oshact/section5-duties

 

The information contained in this article is for informational, educational, and promotional purposes only and is based on information available as of the initial date of publication. It is the reader’s responsibility to ensure compliance with all applicable laws, rules, codes and regulations. If there is any question or doubt in regard to any element contained in this article, please consult a licensed professional. Under no circumstances will Global Industrial® be liable for any loss or damage caused by your reliance on this article.