Dual‑head (two‑headed) LED emergency lights—often called bug‑eye fixtures—are the go‑to solution for commercial emergency lighting. Two adjustable heads let you push light both down the path and across the space for safe LED egress lighting during an outage. This buyer’s guide explains when dual‑head units fit best, how to size and aim them, and which features matter for UL 924 compliance.
Last updated: November 2025
What Are Dual‑Head (Bug‑Eye) Emergency Lights?
A dual‑head emergency light is a wall‑ or ceiling‑mounted fixture with two adjustable LED lamp heads and an internal battery. During a power loss, it automatically provides egress illumination for at least 90 minutes (UL 924). Because the two heads can be aimed independently, you can place one beam down a corridor and the other across the egress path to reduce shadows in corners and intersections. The nickname “bug‑eye” comes from the two protruding lenses on compact housings.
Why pros spec them: easy over‑J‑box installs, fast aiming, low maintenance with LEDs, and predictable inspection outcomes for commercial emergency lighting across offices, retail, schools, healthcare, and more.
When Dual‑Head Makes Sense
- Corridors & common paths: Mount ~7–10 ft AFF; aim one head down‑corridor and one across for hallway/corridor emergency light coverage.
- Small rooms & back‑of‑house: Compact twin‑head units by doors cover offices, telecom closets, storage.
- Large volumes: Use high‑output heads, tighter spacing, or remote heads for tall bays and open areas.
- Exterior egress: Choose wet‑location, gasketed housings; add heaters for cold climates and guards where equipment is exposed.
- Consider other formats when: appearance is paramount (recessed); EXIT + light in one device (combo); or premium finishes (see housing comparison).
Key Specs to Compare
- Lumens & optics: Total output and beam shape. Narrow beams throw down long corridors; wider beams fill rooms. Fully adjustable heads are essential.
- Runtime: Standard 90 minutes. Extended runtimes or higher‑lumen heads need larger batteries. Use the runtime/load calculator.
- Battery & charging: Ni‑Cd is common; LiFePO4 appears on premium units. Self‑diagnostics automate monthly/annual tests and report faults.
- Input & wiring: Universal 120/277 VAC. Remote‑capable bodies can power extra heads—confirm conductor sizing and voltage drop.
- Housing & ratings: Thermoplastic (value), steel (durability/large batteries), die‑cast aluminum (architectural). Verify damp vs. wet‑location and temperature range.
- Mounting: Wall is typical; use end/ceiling canopies where sightlines demand it.
- Options: Time‑delay, tamper‑resistant hardware, cold‑weather packages, Chicago/NYC approvals.
Sizing & Layout Tips
Overlap beams along the egress route. Use the second head to cross‑fill the corridor or room. Field‑tested starting points:
- Spacing: Offices often land at ~25–40 ft between fixtures; wider/taller spaces need tighter spacing or higher‑output heads.
- Aiming: Start with one head down‑corridor (20–40 ft reach) and one across; fine‑tune during the 90‑minute test.
- Obstructions: Avoid soffits, signage, or storage that create shadows.
- Remote heads: A remote‑capable body can serve adjacent restrooms/vestibules; confirm conductors and runtime budget.
See mounting methods and aiming examples in Mount It Right: Installation Options.
Options & Accessories
- Self‑diagnostic testing (SDT): Automates the quick monthly and 90‑minute annual tests; status LED shows codes.
- Time‑delay: Keeps lamps on briefly after power returns—useful with generators.
- Remote head outputs: Extend coverage into small rooms from one power body.
- Guards & security hardware: Wire guards and tamper‑proof screws for high‑abuse areas.
- Cold‑weather & local approvals: Specify for exterior egress or Chicago/NYC jobs.
Use‑Case Snapshots
- Office corridor: Compact thermoplastic every 25–35 ft; adjust heads for intersections and doorways.
- Warehouse aisle (20–30 ft MH): High‑lumen heads and tighter spacing; steel housings for durability.
- Retail/hospitality: Die‑cast architectural bodies; consider recessed pop‑out for clean ceilings.
- Exterior egress: Wet‑location units with heater option; add guards to prevent damage.
Compare to Other Formats
| Type | Best For | Look | Notes |
|---|---|---|---|
| Dual‑head LED (bug‑eye) | Most interiors; egress paths | Compact housing; aimable heads | Broadest use; simplest install |
| Recessed pop‑out | Finish spaces; clean ceilings | Flush until test/outage | Higher cost; more coordination |
| Exit + light combo | Doorways needing EXIT + egress | EXIT face with two heads | One device; check sightlines |
| Remote heads + power unit | Distributed coverage | Small heads; remote cabling | Plan conductor size/distances |
For material differences and durability, see our housing comparison.
Compliance & Testing
- UL 924 listing: Minimum 90‑minute emergency illumination; confirm damp/wet‑location as needed.
- Testing: Monthly quick test and one 90‑minute annual. SDT automates both and logs status.
- AHJ‑friendly: Keep spec sheets and test logs in the life‑safety binder for inspections.
Quick Spec Checklist
- Heads/optics: Aimable LED heads; pair narrow for throw + wide for fill if needed.
- Output/runtime: Meets 90‑minute minimum at required light levels.
- Power: 120/277 VAC input; remote‑capable if feeding extra heads.
- Battery: Ni‑Cd (value) or LiFePO4 (premium); self‑diagnostics preferred.
- Environment: Damp or wet‑location listing; temperature range fits site.
- Housing: Thermoplastic (economy), steel (durable), die‑cast (architectural).
- Mounting: Wall by default; end/ceiling with canopy if needed.
- Unit is UL 924 listed and rated for the environment ✅
- 90‑minute test passed and logged ✅
- Heads aimed to meet path‑of‑egress illumination ✅
- Spec sheet and test records on file ✅
Dual‑Head Categories (At a Glance)
Choose the category that matches your environment and sightlines:
- Compact thermoplastic: Budget‑friendly for offices and corridors.
- Rugged steel / high‑output: Larger batteries for industrial and high‑mount applications.
- Architectural die‑cast: Clean lines for public areas; matches finish spaces.
- Wet‑location: Gasketed housings and optional heaters for outdoor egress.
Tip: If you need EXIT + light in one device, consider an exit/emergency combo; for premium interiors, review recessed pop‑out styles.
FAQ
What is a bug‑eye emergency light?
A bug‑eye is simply a dual‑head emergency light—a compact body with two aimable LED lamp heads for egress illumination during power loss.
Are “dual‑head” and “two‑head” the same thing?
Yes. You’ll also see twin‑head used. All refer to the same two‑headed emergency light format.
Can I use them in hallways and corridors?
Yes—this is their most common application. Aim one head down the corridor and one across to fill shadows.
Do I need self‑diagnostics?
Not always, but SDT saves time by automating required monthly and annual tests and flagging battery or lamp faults.
Can I use dual‑head lights outdoors?
Yes—spec wet‑location housings and cold‑weather kits where needed; use guards in high‑abuse areas.