What’s Covered in This Guide
Types of Exit Signs and Their Power Characteristics
Exit signs come in several different types, each with unique power needs and visibility mechanisms. Understanding these differences helps you choose the right sign for your building’s safety and energy requirements.
Incandescent Exit Signs
These are older-style signs that use small filament bulbs to illuminate the “EXIT” legend. Each bulb typically uses 20–25 watts, making total power usage about 30–40 watts per sign. They run on 120V or sometimes 277V via special wiring. Although they provide reliable light, they consume high energy and require frequent bulb replacements, leading to high long-term maintenance costs.
LED Exit Signs
Today’s standard in exit signage, LED signs use light-emitting diodes and consume as little as 1 to 5 watts. Most models are dual voltage (120/277V), meaning they can be installed in virtually any U.S. building. LED signs last for 10+ years with minimal maintenance and are dramatically more energy efficient than incandescent models.
Photoluminescent Exit Signs
These glow-in-the-dark signs require no wiring or electricity. Instead, they absorb ambient light and emit a green glow during power outages. They must be installed in well-lit areas and can glow for 90+ minutes once fully charged. Ideal for retrofit applications or where electrical wiring is difficult or expensive to install.
Fluorescent and CFL Exit Signs
These signs were an early alternative to incandescent types, using fluorescent tubes or compact fluorescent lamps to reduce energy use to around 8–16 watts. However, they still fall short of LED performance and are now largely obsolete due to mercury content and shorter lifespan.
Tritium Self-Luminous Exit Signs
Tritium signs are powered by low-level radioactive gas that naturally emits light, requiring zero electricity or light exposure. While useful in remote areas or when no power is available, they involve regulatory handling and disposal due to the radioactive material. Lifespan is typically 10 to 20 years before brightness fades below usable levels.
Why Dual Voltage Matters
Most LED exit signs today are manufactured as dual voltage (120/277V). This means they can automatically adapt to whichever supply is available in the building, eliminating compatibility issues. Installers simply connect the wiring to the correct voltage terminals and cap the unused leads.
Choosing the Right Voltage
- Small offices and retail stores: Usually 120V circuits
- Large commercial buildings, warehouses, schools: Likely 277V circuits
Before installing a new exit sign, always verify the circuit voltage or consult a licensed electrician. Connecting a 120V-only sign to a 277V line can result in serious damage or fire risk. Fortunately, dual-voltage LED signs make this much easier and safer by accommodating both standard power systems.
Understanding Wattage and Efficiency
Wattage refers to the amount of electrical power a sign consumes to stay illuminated. Because exit signs operate 24/7, even small differences in wattage can have a significant impact on your electricity bill over time.
Why Wattage Matters
Since exit signs must remain illuminated at all times, power consumption adds up. A high-wattage sign can cost significantly more to operate annually than an efficient one. Here’s a comparison of common types:
| Type | Typical Wattage | Estimated Annual Energy Use |
|---|---|---|
| Incandescent | 30–40 W | ≈ 350 kWh (~$35/year) |
| Fluorescent | 8–16 W | ≈ 140 kWh (~$14/year) |
| LED | 1–5 W | ≈ 44 kWh (~$4/year) |
| Photoluminescent | 0 W | No energy cost |
LED Efficiency Advantages
LED exit signs are by far the most energy-efficient wired option. They last 10+ years and draw only a fraction of the power compared to older technologies. Their internal drivers optimize light output without wasting energy as heat.
U.S. Safety and Compliance Codes
Exit signs aren’t just helpful—they’re required by law. In the United States, key safety standards are governed by OSHA (Occupational Safety and Health Administration), NFPA (National Fire Protection Association), and local building codes. Understanding these requirements ensures your signage meets both visibility and emergency performance standards.
OSHA Requirements (29 CFR 1910.37)
- Exit signs must be continuously illuminated when a building is occupied.
- Externally illuminated signs must receive at least 5 foot-candles of lighting on the surface.
- Self-luminous signs (e.g., tritium or photoluminescent) must provide a minimum luminance of 0.06 foot-lamberts.
- Lettering must be at least 6 inches high with a stroke width of ¾ inch.
NFPA 101 – Life Safety Code
- All exit signs must be listed to UL 924 and visible under both normal and emergency conditions.
- Internally illuminated signs must operate for at least 90 minutes during a power outage.
- Signs must include a backup power source—either a self-contained battery or connection to an emergency circuit.
- Placement must ensure signs are visible from any point in the exit access path (typically not more than 100 feet apart).
UL 924 Certification
UL 924 is the standard that certifies exit signs for emergency use. It confirms that signs meet visibility, luminance, and backup power requirements. When buying an exit sign, always look for this certification mark—it’s essential for code compliance.
Local Code Considerations
Some cities have stricter rules. For example, New York City requires 8-inch red letters and often metal housings. Always consult your local authority having jurisdiction (AHJ) before finalizing your signage choice.
Energy Efficiency by Sign Type
Since exit signs operate continuously, improving their energy efficiency has a measurable impact on utility costs and carbon footprint. Here's how different types of signs compare:
LED Exit Signs
LED models use just 1 to 5 watts and last over a decade without needing lamp replacement. Their low power draw and long life make them the top choice for energy-conscious building owners. They also emit very little heat, reducing cooling loads in climate-controlled spaces.
Photoluminescent Exit Signs
These signs use zero electricity. Once installed in a well-lit location, they absorb ambient light and emit a glow for 90+ minutes during power loss. While they don’t add to your electric bill, they do require proper exposure to consistent lighting in order to meet code.
Fluorescent and CFL Signs
Fluorescent exit signs use more power than LEDs and require more frequent maintenance. While still more efficient than incandescent models, they contain mercury and are rapidly being phased out.
Incandescent Exit Signs
These consume up to 40 watts per sign, generating significant heat and requiring frequent bulb changes. Compared to LED models, they can cost up to 10 times more in electricity and maintenance.
Tritium Signs
These use no power but contain radioactive gas and must be disposed of according to strict regulatory guidelines. They offer long life (10–20 years), but replacement and handling can be costly over time.
How to Choose the Right Exit Sign
Selecting the right exit sign involves more than picking a color or mounting style. You need to ensure compatibility with your building’s electrical system, meet all safety codes, and minimize long-term costs. Here’s how to do it:
1. Determine Your Voltage
Find out if your lighting circuits are running on 120V or 277V. Most modern LED signs support both, labeled as “120/277V dual voltage”. This flexibility ensures compatibility with most U.S. installations.
2. Choose a Power Source
- Hardwired LED signs with battery backup are ideal for most commercial settings.
- Photoluminescent signs are perfect for areas with steady ambient light and where wiring is difficult.
- Tritium signs work in fully dark areas with no power or light source, but involve special disposal.
3. Verify Emergency Backup
Ensure your sign includes a 90-minute battery backup (or is connected to a backup power circuit). This is required by NFPA 101 and most local codes. LED signs with self-contained Ni-Cd or NiMH batteries are the most common solution.
4. Check UL 924 Certification
Always buy a sign that is UL 924 listed. This confirms that it meets visibility, brightness, and backup duration requirements. Without this certification, the sign may not pass inspection.
5. Select Face and Arrow Configuration
- Single face: For wall mounting.
- Double face: For ceiling or end mounting in hallways.
- Directional arrows: Choose models with field-selectable knockouts for left, right, or both directions.
6. Match the Environment
Use wet location rated signs for outdoors or damp environments like garages, kitchens, or warehouses. For tamper-prone areas, choose vandal-resistant or steel housing models. Explosion-proof units are available for hazardous locations.
7. Consider Aesthetics
In lobbies or modern interiors, edge-lit acrylic signs provide a sleek look. These are available in red or green LED, with surface or recessed mounting options. Power requirements are similar to standard LED signs.
Conclusion
Understanding voltage and wattage in exit signs is essential for ensuring your building is both code-compliant and energy-efficient. Whether you’re retrofitting an older system or outfitting a new facility, choosing the right sign can reduce long-term costs while enhancing safety during power outages or emergencies.
For most installations, LED exit signs with battery backup offer the best combination of reliability, efficiency, and low maintenance. If you’re looking to avoid electrical work or want to reduce energy usage to zero, photoluminescent exit signs are an excellent alternative—just be sure they’re placed in well-lit areas. In remote or power-restricted locations, tritium self-powered signs still serve a role, but they come with handling and disposal requirements.
Always check for UL 924 listing, confirm your circuit voltage (120V or 277V), and ensure each sign includes 90-minute emergency operation. These aren’t just recommendations—they’re life-safety requirements backed by OSHA and NFPA 101.