What to Look for When Buying Emergency Exit Signs: A Practical Purchasing Guide for Facility Managers
This guide breaks down the key specifications, certification standards, and installation considerations for emergency evacuation lighting and exit signs. It includes a detailed parameter table to help buyers make informed decisions.
Emergency exit signs, also known as evacuation signage or escape route lighting, are critical safety devices required in all commercial buildings, schools, hospitals, warehouses, and multi‑unit residential buildings. Choosing the right model not only ensures code compliance but also directly affects occupant safety during a power failure or emergency. This article addresses the most common purchasing questions and provides a clear comparison of technical parameters.
1. Types of Emergency Exit Signs
There are three primary types based on power source and operation:
- Self‑Luminous (Non‑Electric): Use photoluminescent materials that absorb ambient light and glow in the dark. No wiring needed, ideal for retrofits, but light output decreases over time. Typical luminance: 30–50 mcd/m² after 10 minutes.
- Battery‑Backup (Maintained / Non‑Maintained): Most common. The sign is connected to mains power and switches to internal batteries during a blackout. Maintained signs are illuminated 24/7; non‑maintained illuminate only during an emergency. Battery life: 3–5 years for Ni‑Cd, 5–7 years for Ni‑MH.
- LED Edge‑Lit or Recessed: Use high‑brightness LEDs with low power consumption. Often available with remote monitoring capabilities. Light output: typically 200–500 lux at 1 meter.
2. Key Technical Parameters Every Buyer Must Check
When evaluating suppliers or product datasheets, focus on these specifications:
| Parameter | Typical Range / Requirement | Why It Matters |
|---|---|---|
| Luminous Intensity (illuminated sign face) | ≥ 100 cd/m² (white) / ≥ 40 cd/m² (red letters) | Ensures visibility at the required distance (30 m per NFPA 101) |
| Battery Type & Backup Duration | Ni‑Cd 1.2V / 3.6V; Ni‑MH 4.8V; Lithium‑ion (newer). Backup ≥ 90 minutes (NFPA / IBC), often 120–180 min. | Longer backup provides more egress time; battery chemistry affects replacement cycle |
| Operating Temperature Range | -10°C to 50°C (indoor); -20°C to 60°C (outdoor/industrial) | Extreme temperatures reduce battery efficiency and LED lifespan |
| Ingress Protection (IP) Rating | IP20 (indoor), IP54 (damp), IP65 (wash‑down / outdoor) | Prevents dust and water ingress; critical for parking garages or food processing areas |
| LED Light Source Life | 50,000 – 100,000 hours (L70) | Reduces maintenance frequency; check LM‑80 test data |
| Charging Time | Typically 24 hours for full recharge | Affects how quickly the sign is ready after a test discharge |
| Compliance Certifications | UL 924 (US), EN 60598‑2‑22 (EU), GB 17945 (China), AS 2293 (Australia) | Mandatory for insurance and local building codes |
3. Common Purchasing Questions Answered
Q: How many exit signs do I need?
NFPA 101 (Life Safety Code) requires an exit sign at every exit door, along egress paths where the exit is not readily visible, and at any change of direction. Generally, one sign per 30 m (100 ft) of corridor with no visual obstruction. Always consult your local fire marshal or code official.
Q: What is the difference between “maintained” and “non‑maintained”?
Maintained signs are always lit (mains + battery trickle). Non‑maintained only come on when mains power fails. For commercial spaces with emergency lighting separate from exit signs, non‑maintained is more energy‑efficient. For theaters or assembly areas, maintained is often preferred so people always see the sign.
Q: Can I install LED exit signs myself?
If the sign is self‑luminous (no wiring) or a direct replacement for an existing unit with the same mounting and voltage, a qualified maintenance person may do it. For new wiring or ceiling‑mounted units connected to emergency circuits, a licensed electrician is required to meet code.
Q: How often should exit signs be tested?
NFPA 101 requires a functional test monthly (press the test button for 30 seconds) and a full 90‑minute discharge test annually. Some local codes mandate quarterly 90‑minute tests. Keep a written log.
4. Material and Design Considerations
- Faceplate: Polycarbonate (impact‑resistant) vs. acrylic (crystal clear). Polycarbonate is preferred for industrial or school environments.
- Mounting Options: Wall‑mounted (end or surface), ceiling‑mounted (pendant or recessed). Confirm compatibility with your ceiling grid (T‑bar, drywall, or concrete).
- Arrow Configuration: Select models with interchangeable arrow inserts (left, right, up, down) to adapt to building layout changes.
- Color: Most jurisdictions require red lettering on a white background or green lettering on white (ISO 7010 for international buildings). Check your local fire code.
5. Recommended Purchase Criteria Checklist
- Verify voltage compatibility (120 V / 277 V common in North America; 220‑240 V in Europe).
- Check that the battery meets the required backup duration (90 min minimum, longer for high‑rise buildings).
- Ensure the sign’s photometric performance exceeds the minimum foot‑candle requirement at the mounting height.
- Look for UL 924 listing (or equivalent local certification) to avoid liability issues.
- Consider units with self‑diagnostic capability (auto‑test) to simplify monthly compliance.
- Compare total cost of ownership: initial price + battery replacement interval + energy consumption (typically 2–5 W for LED, vs. 8–15 W for fluorescent).
By paying close attention to these parameters and consulting your safety code, you can select a reliable emergency exit sign that protects building occupants and meets regulatory requirements for years to come.