C7 lights are the large, traditional lights that you sometimes see on Christmas trees and other displays.  They were very popular back in the 1950s.  You might remember them from the Christmas trees of your childhood or your parents may remember them.  C7 is their technical name.  Contrary to popular myth, they are still easily available and they are the best kind of lights to use for the holidays. 

History

C7 lights were introduced in 1934, by General Electric.  They were considered cream-of-the-crop Christmas lights for their day.  They had parallel circuits, which meant that if one light went out, the others stayed lit.  Initially, only very rich people were able to afford to buy C7 lights; they were very expensive. 

After World War II, C7 lights really became popular.  Throughout the 1950s, everyone used them for Christmas lights.  From the 1960s onward, little twinkle lights have become more and more popular and nearly everyone uses little lights today, but C7 lights are still the best lights to use for the holidays.   

Some interesting facts

C7 lights can still be purchased today.  The best places to go to buy C7 lights are large chain department stores.  They are also available on the Internet and on eBay.  They are available as clear or colored bulbs and as opaque or transparent.  The technical term for opaque lights is ceramic.  The technical term for see-through lights is transparent.  Below, I have included pictures of ceramic and transparents C7 lights.

Ceramic                                            Transparent

I recommend using ceramic bulbs because they give off a warm, soft glow and not the harsh glare of the filament that transparent lights give.  Transparent lights are hard on the eyes.  Whatever you do, don't use ceramic and transparent C7 lights on the same tree.  Taken together, they look as good as a tuxedo with tennis shoes. 

In addition, I always recommend using multicolored sets of lights because they make your tree look bright, cheerful and festive, no matter what kind of ornaments you use.  White lights make your tree look cold or washed out.  Colored lights look bright and cheerful and look like candy on your tree.

Here are some other facts about C7 lights. 

• C7 lights use parallel circuits.  That means that if one bulb burns out, the others stay lit!  No more searching for the burnt out bulb.
• C7 lights are long-lasting.  You can easily get a good ten years' use out of a set of C7 lights.  You don't need to buy new sets every year.  In the long run, that saves you money. 
• C7 lights are cool-burning, at 5 watts each.  They do not get hot and they are no more dangerous on your tree than the little twinkle lights or LED lights.
• They are also energy efficent.  For example, you have a six-foot tree.  Fifty C7 lights will make your tree look bright and festive.  They burn at 5 watts each, so you use a total of 250 watts with the C7 lights.  To achieve the same effect with the little lights, you would need to use at least 500 little lights.  They burn at 1 watt each, so that's a total of 500 watts; double the wattage you would use with C7 lights.  You save energy with C7 lights. 
• The sockets of C7 lights have molded clips.  You can clip them to your tree's branches and they'll stay put, unlike the little lights, which always slide around. 

A typical C7 light set

A typical C7 light set usually consists of twenty-five sockets, has both a male and female plug, and is twenty-five feet long.  You can hook up to two strings of C7 lights.  The sockets and cord are usually green, so as to blend in with the tree.  On a typical C7 light set, the bulbs come in colors of red, blue, white, orange and green.  

One thing that is interesting to note.  There is one color that you expect to find in a set of C7 lights, but don't.  That color is yellow.

Yellow C7 lights are very hard to find.  They cannot be bought at any store in the U.S., but as I always say, a tree without yellow lights is like a sandwich without bread.  Below, I have included a drawing of two Christmas trees, one with yellow lights and one without.  See the difference!

A Tree without yellow lights is like a sandwich without bread!

However, it is possible to buy yellow C7 lights on the Internet and on eBay.  As eBay's advertising slogan goes, 'whatever IT is, you can find IT on eBay' and that includes yellow opaque C7 lights.  Yellow C7 lights can be added to existing strings, to complete your color spectrum.

Lighting your tree

How many lights do you need?

To figure out how many lights you need for your tree, multiply your tree's height by its width, by 2 (x3 if your tree is 8 feet or taller).  For example,

6 feet high X 4 feet wide X 2 = 48 lights. 

*Note, strings of C7 lights usually have 25 sockets, so in this case, you would need 50 lights.  When in doubt, always err on the side of using too many lights. 

Putting up the lights

I have developed a unique way of putting lights on a Christmas tree.  It involves a lot of meticulous work, but it eliminates much of the aggravation of putting up lights. 

1.  Walk around the tree and drape the strings of sockets on the tree as you go.

2.  Space and clip the sockets.  Make sure that the sockets are equally spaced.  You don't want them to clump up in one part of the tree, or be too far spaced apart.  Once you have the sockets properly spaced, clip each one to the nearest branch. 

3.  Screw each bulb into a socket.  Once you've got all the sockets secured, go round the tree and screw each bulb into a socket.  This allows you to achieve a proper balance and distribution of colors; in other words, screwing each bulb into a socket makes sure you don't have two red lights or two blue lights next to each other. See below what a difference screwing each bulb makes.

If you screw in each bulb                         If you don't screw in the bulbs

In addition, by screwing the bulbs into the sockets once the sockets are on the tree, you reduce the chance of breaking any light bulbs.         

Other lighting tips

When buying C7 lights for your tree, always buy more lights than you think you'll need.  For example, if you think you'll need two strings of lights for your tree, buy four strings.  The tree may require more lights than you had imagined, or if a light burns out, you'll have a ready source of replacement lights.  C7 lights are durable and long-lasting, but you can count on having at least one bulb burn out during the holidays and you need a ready supply of replacement lights, and you should replace the burnt-out bulb with another bulb of the exact same color.  In the unlikely event that a string shorts out, you'll have replacement string on hand, if you buy more strings of lights than you think you'll need.  It's better to have and not need than to need and not have.

In the stores, C7 lights are marketed as Indoor/Outdoor lights.  This is just a marketing ploy.  I do not recommend using C7 lights outdoors.  They are just not designed for outdoor use or to stand up to the weather.  For outside decorating, you should really use the larger C9 lights, which are designed to be heavy-duty and weather-resistant.

In conclusion

I hope this guide has been helpful, that it has given you some ideas about decorating your tree next Christmas.  With the information I provided in this guide, you should have an easy time making your tree look bright, cheerful and festive and make it stand out from the crowd.