LED vs Incandescent: The Complete Comparison
From Product Knowledge: In our Definitive Guide to Professional Lighting Products, we introduced the major light types. This article provides the complete comparison between LED and incandescent technology.
The Shift Has Already Happened
If you started in this industry more than five years ago, you remember when incandescent was the default. C9 ceramic bulbs on SPT-2 wire, warm glow, simple wiring. The look was iconic. The callbacks were constant.
Today, roughly 90% of professional holiday lighting installations use LED. The economics made that decision for us. But "LED is better" is too simple. There are real tradeoffs, and understanding them makes you a better installer and a more credible advisor to your clients.
Energy Efficiency: The Numbers That Changed Everything
A traditional C9 incandescent bulb draws 7 watts. A string of 25 pulls 175 watts. Run four strings end-to-end on a roofline and you are at 700 watts from one circuit just for the roofline. Add trees, bushes, and window outlines, and a single residential job can pull 2,000-3,000 watts.
The LED equivalent C9 draws 0.6-1.0 watts per bulb. That same 25-bulb string runs at 15-25 watts. Four strings: 60-100 watts. You just freed up 600 watts of circuit capacity for the rest of the property.
This is not just a selling point for the client's electric bill. It fundamentally changes what you can do on a job. With incandescent, you spent time mapping circuits, counting outlets, worrying about tripped breakers. With LED, a typical residential property can run the entire display off a single 15-amp circuit. That means fewer extension cord runs, less time tracing power paths, and far fewer midnight callback texts about half the display going dark.
Real-world math: A 2,500-bulb residential display using incandescent C9s draws roughly 17,500 watts. The same display in LED draws about 2,000 watts. At $0.14/kWh running 6 hours per night for 45 days, that is $66 vs $7.50 in electricity. Over a five-year client relationship, the energy savings alone exceed the cost difference of the product.
Color Rendering: Where Incandescent Still Has Defenders
Here is where the honest conversation starts. Incandescent light has a CRI (Color Rendering Index) of 100 -- it is the reference standard. The warm, full-spectrum glow of a tungsten filament renders reds, oranges, and earth tones beautifully. It is the look people associate with "Christmas."
Early LEDs were terrible at this. Blue-shifted, harsh, that sterile "airport bathroom" look. Modern LEDs have closed the gap significantly. Quality warm white LEDs in the 2700K range now achieve CRI ratings of 80-90. At night, viewed from the street at 30-50 feet, most people cannot distinguish them from incandescent.
But "most people" is not all people. You will encounter clients -- particularly in affluent neighborhoods with older homeowners -- who insist they can tell the difference. They are not wrong. Side by side, in a controlled environment, incandescent warm white has a slightly richer amber quality. LED warm white, even at 2700K, tends to have a faintly cleaner, less amber character.
The practical solution: do not mix them. If a client has existing incandescent and wants to add LED, replace everything. Mixed installations look worse than either technology on its own. For a deeper dive into the warm white color question, see The Warm White Debate.
Heat Output: Safety and Material Impact
An incandescent C9 bulb reaches surface temperatures of 150-175 degrees Fahrenheit. A C7 hits 100-130 degrees. Mini lights run 50-80 degrees. These temperatures matter for three reasons:
Fire risk. Incandescent lights in direct contact with dry foliage, roof debris, or fabric create genuine fire hazards. You have to maintain clearance from combustible materials. LED surface temperatures rarely exceed 100 degrees even in enclosed fixtures.
Material degradation. Heat accelerates the breakdown of plastic sockets, wire insulation, and clip materials. Incandescent strings degrade faster not just from age, but from the thermal cycling of their own heat output. Every on/off cycle is an expansion/contraction cycle.
Installation flexibility. LED's low heat means you can wrap live garland, stuff lights into tight architectural details, and make contact with vinyl siding without concern. Try that with incandescent C9s and you are melting siding, scorching cedar, and creating liability.
Lifespan and Durability
Incandescent C9 bulbs are rated for 2,000-3,000 hours. In a typical holiday season of 270 hours (6 hours/night x 45 nights), that is 7-11 seasons. Sounds reasonable until you factor in breakage, thermal shock, and socket corrosion. In practice, you will replace 10-20% of incandescent bulbs per season due to burnout and handling damage.
LED holiday lights are rated for 25,000-50,000 hours. Even at the low end, that is 90+ seasons of theoretical life. Obviously, other components fail first -- connectors corrode, wire insulates degrades, clips break. But the LED chip itself is almost never the failure point. See What Fails First for the real weak points.
The durability story extends to physical handling. Incandescent bulbs are glass. LEDs are encapsulated in epoxy or polycarbonate. You can drop a box of LED C9s off a ladder and lose nothing. Drop a box of incandescent C9s and you are sweeping up glass and pulling replacement bulbs from your truck stock.
Dimming and Control
This is one area where incandescent has a genuine technical advantage. Incandescent bulbs dim beautifully on a standard TRIAC dimmer. The color shifts warmer as you dim, which looks natural and appealing. The dimming curve is smooth and predictable.
LED dimming is more complicated. Not all LED strings are dimmable. Those that are require compatible dimmers, and even then you can encounter flicker, pop-on (lights snap on at a minimum threshold instead of fading up), and uneven dimming across a string. Quality commercial LED strings with built-in PWM dimming solve most of these problems, but they cost more.
If a client wants subtle dimming effects -- candlelight flicker, slow fade transitions -- make sure you are specifying dimmable LED product and the right controller. Do not assume any LED string will dim smoothly on any dimmer. For more on this, see Power & Controllers.
Cost Analysis: First Year vs Five Years
Incandescent first-year costs (per 100-foot roofline):
- 4 strings of 25 C9 bulbs: $40-60
- Higher wattage extension cords (14 AWG): $30-50
- Replacement bulbs (10% spare stock): $5-10
- Total: $75-120
LED first-year costs (per 100-foot roofline):
- 4 strings of 25 LED C9 bulbs: $80-140
- Standard extension cords (16 AWG adequate): $20-35
- Replacement bulbs: $0-5
- Total: $100-180
LED costs 30-50% more upfront. But by year three, the incandescent installation has consumed $15-30 in replacement bulbs, required a callback or two for burned-out sections, and the client has paid $100+ more in electricity. By year five, LED is cheaper in total cost of ownership -- and that is before you factor in your labor for replacements and callbacks.
The real cost advantage of LED is your time. Every callback you do not make, every replacement bulb you do not install, every breaker you do not troubleshoot is time you spend on the next installation generating revenue.
When Incandescent Still Makes Sense
There are legitimate cases for incandescent:
Historic properties and period-accurate installations. Some historic districts and event venues specifically want the incandescent look for authenticity. If the client is willing to pay for the maintenance and energy costs, respect the choice.
Budget-constrained first-year clients. A new client who wants to "try out" professional lighting at the lowest possible first-year cost may start with incandescent. Be transparent about ongoing costs and plan the LED upgrade conversation for year two.
Specialty applications. Certain vintage-style Edison bulbs and decorative filament lamps are only available in incandescent. These are accent pieces, not workhorse products.
Existing inventory. If you have hundreds of incandescent strings in storage, use them where appropriate while transitioning to LED. Throwing away working product is not good business.
Making the Recommendation
When a client asks "LED or incandescent?" your answer should be LED in almost every case. But frame it correctly. Do not sell LED on technology -- sell it on results. Less chance of problems during the season. Lower electric bill. Brighter, more consistent display from week one to takedown day. No burned-out bulbs creating dark spots.
Save the incandescent conversation for clients who specifically request it, and always provide the full picture on maintenance and operating costs.
Key Takeaways
- LED uses 85-90% less energy than incandescent, fundamentally changing circuit planning and enabling larger displays on existing electrical infrastructure
- Modern warm white LEDs (2700K, CRI 80-90) are visually indistinguishable from incandescent at typical viewing distances, but never mix the two technologies in one installation
- LED's lower heat output, physical durability, and near-zero replacement rate make it cheaper in total cost of ownership by year three despite higher upfront pricing
- Incandescent still has legitimate applications in historic properties, specialty accent pieces, and budget-constrained first-year installations
What's Next
If you've chosen LED (as most professionals do today), the next question is color temperature. The warm white debate has strong opinions on both sides.
Next: The Warm White Debate: 2700K vs 3000K and When It Matters