Christmas Lights Lingo!
Christmas Lights Glossary
Every Term You’ve Ever Wondered About — Explained
From 5mm to wire gauge, here’s your one-stop dictionary for every spec, shape, and technical term in the Christmas-light world.
5mm
Tiny, pencil-eraser-sized LED lens (also called wide-angle or conical). The cone shape inside spreads light in every direction, making 5mm strings appear the brightest LED mini lights available.
Amp / Amp Usage
Measure of electrical current (think “water flow”). More strings connected end-to-end = higher amps. Exceed the fuse or breaker rating and the fuse blows (or worse).
Bulb Voltage
U.S. household power is 120V, but mini-light bulbs are usually 2.5V, 3.5V, or 6V. Always match replacement bulbs to the original voltage or they’ll burn dim or burn out fast.
C6 • C7 • C9
Classic strawberry-shaped bulbs. C6 = smallest (≈¾″), C7 = candelabra base (E12), C9 = intermediate base (E17). The retro look everyone pictures when they think “Christmas lights.”
Dimmable • Full-Wave Rectified
Dimmable = smoothly fades with a dimmer switch. Full-wave LEDs have circuitry that eliminates visible flicker (no more 60 Hz buzz that makes your eyes tired).
End-to-End • Stackable Plug
End-to-end = male + female plugs so you can connect sets. Stackable plugs have a female receptacle built into the male plug — perfect for plugging dozens of sets into one spot on the tree trunk.
Icicle • Curtain • Net Lights
Icicle = staggered drops (classic roofline look). Curtain = all drops same length. Net = perfect grid for bushes and hedges.
LED vs Incandescent
LED = semiconductors, cool to touch, use ~10% the power. Incandescent = glowing filament, warm and nostalgic, but power-hungry and fragile.
M5
Traditional “rice” or faceted mini-light shape in LED form — textured surface looks like a tiny frozen icicle.
Maximum Connectivity
The safe limit of how many identical sets you can plug end-to-end. Exceeding it blows fuses and creates fire hazards.
Series vs Parallel Wired
Series (mini lights) = one circuit; one bulb out affects many. Parallel (C7/C9 cords) = constant voltage; cut to fit, one bulb out doesn’t affect others.
SPT-1 / SPT-2
Insulation thickness on 18-gauge cords. SPT-2 is slightly thicker and more durable; both rated for 10 amps.
Watts
Power = Volts × Amps. The true measure of how much electricity something uses (and how much it costs to run).
Wire Gauge (AWG)
Lower number = thicker wire. 20-22 AWG is common for mini lights; 18 AWG for C7/C9 cords; 16 AWG or lower for heavy commercial use.
IP65
“Dust-tight and protected against water jets.” Perfect for outdoor lights that will see rain and sprinklers but not be submerged.
IP67
“Dust-tight and can be submerged in up to 1 meter of water for 30 minutes.” The gold standard for commercial-grade outdoor Christmas lights that live through Texas downpours.
Lumens
The modern measure of actual visible brightness (not watts!). Rough guide:
• Traditional incandescent mini = 2–4 lumens per bulb
• Standard LED mini = 8–15 lumens per bulb
• C9 LED = 40–80 lumens per bulb
Higher lumens = brighter glow without using more power.
Kelvin (Color Temperature)
Measures the “warmth” or “coolness” of white light:
• 2200K–2700K = Warm White (classic cozy incandescent glow)
• 3000K–3500K = Soft White (slightly brighter, still cozy)
• 4000K–5000K = Pure/Cool White (crisp, modern daylight look)
• 5000K+ = Bright White (very clean, almost bluish)
Lower Kelvin = warmer, yellower light; higher = cooler, whiter.
Still have a term that’s stumping you?
Questions still burning? Drop us a line via our contact page.
— Shellie & the Christmas Light Source Team
