No-power, always-on exit signage—what tritium (self-luminous) signs are, when to use them, and how to stay compliant.
Quick definition: A tritium (self-luminous) exit sign uses sealed glass tubes with tritium gas to glow continuously—no wiring, batteries, or charging light. It stays illuminated during power outages and is commonly rated for 10- or 20-year service life.
Last updated: October 2025
Overview
Tritium exit signs—also called self-luminous exit signs—glow continuously without electricity or batteries. That makes them a smart fit for remote or difficult-to-wire areas, and a reliable layer of life safety during outages. You’ll see them specified in stair towers, over discharge doors, and in retrofit projects where opening walls or pulling new branch circuits isn’t practical.
- Always on: self-powered illumination 24/7, even during blackouts.
- No wiring, no chargers: faster installs and zero energy use.
- Long service life: commonly sold in 10-year and 20-year models.
How Tritium Exit Signs Work
Inside each sign are sealed glass tubes containing tritium gas. As tritium decays, it releases low-energy particles that excite a phosphor coating inside the tube—producing a soft, uniform glow. The tubes are fully sealed and mounted behind the EXIT legend, so the sign is illuminated without any external power source or replaceable lamps.
Want a deeper dive? Read how self-luminous exit signs work for more detail.
Where They Make Sense
- Hard-to-wire locations: historic buildings, block walls, finished ceilings.
- Retrofits on a deadline: replace failed or non-compliant signs without opening walls.
- Remote areas: outbuildings, mechanical yards, or long runs where voltage drop is a concern.
- Energy-sensitive facilities: eliminate connected load and charger maintenance.
Code & Compliance (UL 924 / NFPA 101)
Modern tritium exit signs are built to meet UL 924 performance for emergency egress visibility. NFPA 101 (Life Safety Code) permits internally illuminated signs; your Authority Having Jurisdiction (AHJ) may specify letter color, mounting height, and placement. As with any life-safety device, choose products with clear listings and documentation, and keep them installed per the manufacturer’s instructions.
- Confirm letter color (red/green) and viewing distances.
- Mount where the legend is plainly visible along the egress path.
- Keep labels legible and unobstructed.
Installation & Retrofit Advantages (No Wiring)
Because they’re self-powered, tritium signs install quickly—no branch circuit, no test switch wiring, no conduit. In many retrofit scenarios, crews can replace non-compliant signs one-for-one with minimal disruption. For field tactics and labor tips, see our no-wiring retrofit guide.
- Labor savings: mount and go—no panel schedules or voltage-drop math.
- No energy draw: reduces operating cost and carbon load.
- Consistent visibility: glow is independent of building power and ambient light.
Owner Duties: Labeling, Records & Incidents
- Keep manufacturer and safety labels intact and legible.
- Maintain an inventory (model, serial no., install location, install date).
- Update your radiation-safety contact and facility details when they change.
- Report any lost, stolen, or broken signs per regulator guidance.
For the complete ruleset and a printable checklist, see the Tritium Compliance Handbook.
End-of-Life & Disposal (Simple & Compliant)
When a sign reaches end-of-life (or if one is damaged), do not discard it in the trash. The compliant path is to return it to a licensed facility or certified recycler. Most providers supply packaging, chain-of-custody paperwork, and shipping instructions. Keep your inventory records updated so you can match serial numbers to shipments. Follow the steps in our Tritium Exit Sign Disposal (step-by-step) guide.
- Identify: Confirm model/serial from your inventory.
- Package: Use the recycler’s kit and follow labeling instructions.
- Ship: Return to a licensed facility via provided carrier steps.
- Document: Save chain-of-custody and update your inventory.
Tip: Plan disposal when you schedule replacements—install new signs and send expired units out in the same work order.
Tritium vs LED vs Photoluminescent
| Type | Best For | Power/Testing | Notes |
|---|---|---|---|
| Tritium (Self-Luminous) | Hard-to-wire, remote areas, fast retrofits | No wiring, no energy, no monthly push-tests | Plan for compliant end-of-life return |
| LED (Wired + Battery Backup) | Most interiors; broad option set | Needs power, charger, monthly/annual tests | Lowest total cost in many standard installs |
| Photoluminescent | No-power goals where ambient light is adequate | No wiring, but requires charging light | Verify illuminance and viewing distance |
For cost modeling and payback math, see our Exit sign ROI comparison.
FAQ
How long do tritium exit signs last?
Most are rated for 10 or 20 years of continuous illumination. Choose a model that aligns with your replacement cycles.
Are tritium exit signs safe?
When intact and used as directed, they’re considered low-risk. Follow label instructions and your local reporting requirements.
Do they meet code?
Look for UL 924 listing and install per the manufacturer’s instructions. Your AHJ may specify color, mounting, and spacing.
What if one breaks?
Clear the area, restrict access, and follow the manufacturer/regulator guidance for reporting and cleanup. Then arrange compliant disposal.
Are tritium exit signs legal to own and use?
Yes—when used under a general license and kept in good condition with labels intact. Follow owner responsibilities and report incidents per your regulator.
Can I throw away an expired tritium exit sign?
No. Don’t landfill or scrap it. Return the sign to a licensed facility or certified recycler. Use our disposal guide for step-by-step instructions.