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About C7 & C9 Christmas Lights

C7 & C9 Christmas lights have been a mainstay in holiday displays across the nation since the 1920's, but it's not uncommon for Christmas enthusiasts to have questions about the differences between C7 & C9 Christmas lights. With the wide variety of other Christmas light bulb styles avaiable on the market today, its easy to get discouraged when selecting the light that is appropriate for your indoor or outdoor Christmas display.

C7 and C9 Christmas lights were both introduced by General Electric in 1934 and 1927 respectively, and gained popularity in the 1950's as the cost of manufacturing these products decreased significantly. Contrary to popular belief, these bulb styles are still widely available today and relatively low cost compared to the alternative LED Christmas light styles.

Incandescent vs. LED Bulbs

Most people prefer incandescent bulbs for their classic look and feel, but their are some real advantages to Light Emitting Diode (LED) Christmas lights, such as:

LEDs yields an 80 to 95% energy savings as they consume between 0.5 and 1.25 watts compared to the 5-10 watts/incandescent bulb
LED bulbs are rated for over 50,000 hour life, compared to 3,000 hours for incandescent
LED bulbs burn cool to the touch, where incandescent bulbs heat up due to their filaments
Faceted LED bulbs are often viewed as "brighter" bulbs because of the way they diffuse light

C7 & C9 Bulb Size & Wattage

Both bulb styles vary in size and wattage, and the two bulb types cannot be mixed within the same light set as the lights often will not illuminate, and pose a fire hazard.

LED vs. Incandescent Bulb Size

Wattage Bulb Type Bulbs Per 15 Amp Circuit
(standard residential)
Bulbs Per 20 Amp Circuit Energy Savings
(Compared to a 10 Watt Bulb)
0.6 C7 LED 2400 3200 94% Savings
1.0 C9 LED 1440 1920 90% Savings
2.5 C7 Energy Efficient Incandescent 576 768 75% Savings
3.7 C9 Energy Efficient Incandescent 389 519 63% Savings
5 C7 Incandescent (Standard) 288 384 50% Savings
7 C9 Incandescent (Standard) 205 274 30% Savings
10 C9 Incandescent (Traditional) 144 192 0% Savings

C7 & C9 LED Retrofits

C7 & C9 Christmas are often sold prelamped strings with either LED or Incandescent bulbs. LED Retrofit bulbs can be purchased from many Christmas stores which can be used to convert your incandescent C7 or C9 light sets to their energy efficient LED counterpart.

LED Retrofit bulbs are sold in a variety of styles including:

The Faceted LED bulb/lense style contains facets similar to what you would see on a diamond, which are used to refract the light in multiple directions, giving the LED faceted bulb a glimmering appeal.
The Smooth LED bulb/lense is also sometimes called the "transparent" LED. This less common bulb/lense is contructed without the facets, giving the LED bulb a more narrow light dispersion pattern.

All C7 or C9 LED Christmas Lights, whether you've purchased a prelamped set, or LED retrofit bulbs are made with either 3 or 5 diodes. Bulbs with 5 diodes are often much brighter, but a little more expensive than the 3 diode version. Be sure when you're comparing prices on prelamped sets or LED retrofits that you're considering the number of diodes included on each product!