Christmas light glossary

A

Amps and circuit load

How much current the display draws. Lights run for hours at a time, so electricians generally keep them to about 80% of a circuit's rating – around 12 amps on a 15-amp circuit. Big displays are split across several circuits.

Animated display

Lights that change, chase or run in sequence, driven by a controller. Priced as a custom job – Angi puts custom and animated displays at $1,000 to $8,000.

B

Bulb spacing

The distance between sockets on a strand, often 8, 12 or 15 inches for large bulbs on a roofline. Wider spacing uses fewer bulbs and gives a cleaner, more classic line.

Bulk light line

Empty socket wire sold on a spool, cut to the exact length of your roofline and fitted with separate bulbs. What most professional installers use instead of boxed strands.

C

C7 bulb

A mid-sized bulb, roughly an inch wide, with a candelabra (E12) screw base. Used on smaller homes, walkways and where C9s would look too big.

C9 bulb

The large, classic roofline bulb, about 1.25 inches wide and 2.5 inches tall, with an intermediate (E17) screw base. The standard choice for professional roofline work.

Candelabra base (E12)

The small 12 mm screw base used by C7 bulbs.

Clips

Plastic fasteners that hold lights on gutters, shingles, ridges and railings without nails or staples. All-in-one clips work on both gutters and shingle edges.

Colour temperature

How warm or cool white light looks. “Warm white” is the soft, yellowish glow of old incandescent bulbs; “pure” or “cool white” is crisper and bluer. Ask to see both at night before you choose.

Commercial holiday lighting

Displays for businesses, HOAs, shopping centres and offices, quoted site by site. See commercial installers – 886 in this directory.

Commercial-grade lights

Heavier-built lights sold to professionals rather than in stores, usually with thicker wire and replaceable bulbs. Most installers use them, often on a lease.

Controller

The box that powers and programs permanent or animated lights, usually paired with a phone app.

D

Design mock-up

A photo of your home with the proposed lights drawn on, used to agree the design before installation.

Dusk-to-dawn timer

A timer or light sensor (photocell) that switches the display on at dusk and off at a set hour or at dawn, so nobody has to plug anything in.

E

E17 base

The intermediate screw base used by C9 bulbs – larger than a candelabra base, smaller than a household bulb.

Eaves

The lower edge of the roof that overhangs the wall. Seasonal lights clip along it; permanent tracks are often mounted underneath it.

ETL listed

Certified by Intertek, a nationally recognized testing laboratory, as an alternative to UL. Look for outdoor-rated certification on lights and cords.

Extension cord, outdoor-rated

A cord built for wet and cold conditions. Indoor cords should never be used outside.

F

Faceted bulb

A bulb with a cut-glass style surface that scatters light for extra sparkle. Common on C9 LEDs.

Fascia

The board along the edge of the roof where the gutter is attached. A common mounting surface for permanent tracks.

Full package

Roofline plus windows, doors, trees, bushes and extras. Angi and HomeGuide both put it at $750 to $5,000. See the cost guide.

G

Gable

The triangular wall under a peaked roof. Outlining gables adds footage but gives the classic “house shape” outline.

Garland

A rope of artificial greenery, often pre-lit, hung around doors, porches and railings.

GFCI

Ground-fault circuit interrupter: an outlet or breaker that cuts power instantly if current leaks, for example into water. Outdoor outlets should be GFCI protected, which is also why lights sometimes trip in heavy rain.

H

HOA rules

Homeowners associations sometimes limit when lights can go up, how long they stay, or whether permanent lighting is allowed. Check before you sign.

I

Icicle lights

Strands with short vertical drops that hang from the eaves like icicles.

Incandescent

Traditional bulbs that glow by heating a filament. Warmer-looking, but they use far more power: Angi estimates $30 to $75 a month to run an incandescent display against $5 to $20 for LED.

L

Lease

When the installer supplies lights that stay theirs. You pay each season; they install, maintain, remove and store them. Lower first-year cost, no storage, but you never own the lights.

LED

Light-emitting diode. The standard for professional installs today: cooler, tougher and far cheaper to run than incandescent.

Linear foot

One foot of roofline or edge that gets lit. The unit most installers price by – $2 to $5 a foot according to Angi, $5 to $12 according to HomeGuide.

M

Mini lights

Small bulbs on thin wire, used to wrap trees, bushes and railings. LED versions come in shapes such as 5 mm wide-angle and M5. Also called fairy or Italian lights.

Minimum charge

The least an installer will take a job for. Angi puts typical minimums at $150 to $300.

N

Net lights

Mini lights woven into a mesh that drapes over bushes for even coverage.

P

Parallel wiring

Each socket is wired straight to the line, so one failed bulb does not darken the rest. Standard on C7 and C9 strands.

Permanent lighting

LED lights in a track mounted along the roofline that stay up all year and change colour from an app. HomeGuide puts it at $20 to $40 a foot installed. See permanent Christmas lights – 578 installers here offer it.

Pixel

An individually controllable LED. Permanent systems are built from pixels, which is how they show patterns and moving effects.

R

Retrofit bulb

A separate bulb that screws into a socket on bulk light line. Easy to replace when one fails.

RGB and RGBW

LEDs that mix red, green and blue light to make any colour. RGBW adds a dedicated white for a truer warm or cool white.

Ridge line

The top edge where two roof slopes meet. Lighting it adds footage and usually steeper, slower work.

Roofline

The edges of the roof – eaves, gables, peaks – that get outlined in lights. “Roofline only” jobs run $250 to $1,500 (Angi, HomeGuide).

Rope light

Small bulbs sealed inside a flexible clear tube. Used along paths, railings and steps.

S

Series wiring

Bulbs wired one after another. In older sets one failed bulb could darken the whole strand; modern mini lights use shunts to stop that.

Service call

A visit during the season to fix a strand that has gone out. Often included in a professional package – ask.

Shunt

A tiny wire inside a mini-light bulb that lets current bypass a failed filament, so the rest of the strand stays lit.

Soffit

The underside of the roof overhang. Permanent tracks are often mounted here to stay out of sight.

SPT-1 and SPT-2 wire

Grades of light-line wire. SPT-2 has thicker insulation than SPT-1 and is the usual choice for commercial-grade roofline lights.

Storage

Keeping the lights over the summer. Installers who lease lights usually store them; 377 of the 1210 installers here mentioned storage on their websites.

Stringer

A boxed strand with the bulbs already attached, the kind sold in stores. Quick to use but can't be cut to length.

T

Takedown

Removing the lights after the season. HomeGuide notes most professionals recommend taking holiday lights down by mid-January, and puts takedown on its own at $100 to $400.

Tree wrapping

Wrapping trunks and branches in mini lights. Priced separately from roofline work, by tree size and density.

U

UL listed

Certified by UL, a nationally recognized testing laboratory. Look for listings marked for outdoor use on lights, cords and timers.

V

Vampire plug

Installer slang for a slide-on plug that clamps onto bulk wire, so a strand can be cut to the exact length of your roofline.

W

Warm white

The most requested colour for rooflines: a soft, golden white like old incandescent bulbs. See colour temperature.

Wreath

A ring of greenery, often lit, hung on doors, windows or gables.

Sources

• Christmas Designers – C7 vs C9 Christmas lights – bulb sizes, bulk line and retrofit bulbs; read September 22, 2026
• Wikipedia – Christmas lights – series wiring and shunts; read September 22, 2026
• Angi and HomeGuide cost guides – prices quoted above, dated on our cost guide