What is that specification?

January 12, 2019

Shopping for Christmas lights and have Questions about what all the specifications mean?

On each product right after the description is a table of specifications. Right under the product description. Here is a sample of one of those tables.

Different products will have different specs and even though we try to keep all the tables similar, with 1400+ products, some of the specs might “jump around” on the table.

Here is a quick guide to the specifications for our major product lines.

Light Strings (Pre-wired LED and Incandescent)

Bulb Type: Incandescent or LED

Pay close attention to this specification. Incandescent bulbs are traditional, glass bulbs that are filament based. Traditional and cost effective, note that these light strings can be run either a maximum of usually 5 or 10 strings in series. (Check the maximum connectivity number to confirm how many can be run in series.)

LED bulbs is a state of the art technology using semiconductors to produce lights. Ultra low current, these strings us up to 90% less electricity than traditional sets and can be run many more strings in series. (Check the maximum connectivity number to confirm how many can be run in series.)

Color of Bulb, Color of wire: Pretty self explanatory.

Number of bulbs. The total number of bulbs – either LED or incandescent – on the string.

Spacing between bulbs. Distance between the glass or the LED bulbs. Note that the smaller lenses are generally 4 inches apart and the larger bulbs (C7 and C9) are 8 inches apart.

Bulb shape. Glass bulbs are the traditional shape that are commonly known as Christmas tree lights. LED lenses are polycarbonate plastic and come in a wide variety of shapes. Choose your favorite.

Replaceable bulbs. Indicates whether or not the bulb can or cannot be removed and replaced.

For most LED light strings the answer here is no so if you need to be able to remove the bulbs for your project, this type of set might not work. Most incandescent mini light bulbs can be replaced and extra bulbs are shipped with the strings.

Here’s what that looks like. See that this is a pre-wired string. The bulbs cannot be removed or replaced.. The cool thing about this style of light string is that somer versions can be connected over 1000 feet end-to-end in a single circuit and plugged into a single outlet.

Pre-wired LED light string

Total length. The approximate length of the string including the lit part and the wire lengths between the plugs and the first or last bulbs.

The actual length of a string of lights can vary due to “twist” in the wiring harness and cause a variation of a couple of inches. The tighter the twist the shorter the string and the looser the twist the slightly longer the string will be.

Lit length. The length of between the first and last bulb of the set.

Lead wire length. Distance between male plug and first bulb.

Here is a photo of the 36 inch lead wire on a set of craft lights.

Tail wire length. Distance between female plug and last bulb.

Tail length: Length of wire between last plug and female plug. Note that the sum of the lead length and tail length will be the distance between the light strings when wired in series.

Gauge of wire. The thickness of the wire. The smaller the number the bigger the wire.

Included Replacements. A list of what’s included in a little clear plastic envelope that is shipped with your lights.

Maximum Sets Run in Series. This is the maximum number of lights strings that can be run end to end. To prevent damage to light sets, do not exceed this number. Keep this number in mind as you plan your project.

Certification. Indicates if the set is UL approved. (Note, bulbs and cords that are sold separately are not rated by UL.

Warm up during operation. Indicates if the light set heats up. Make a note of this is you are installing lights in a place where heat might build up.

Plug Type

Connection Option #1: Male/Female Plugs

This is a standard male/female plug set – the most common configuration on Christmas tree mini lights. The male plug in this photo is also not “stackable” which means that this string can only be plugged in end-to-end.

Connection Option #2: Single Male Plug – May Be Stackable

If a string has a single, stacked, male plug, that means that (in the case of craft lights) the string of lights has a single male plug (no female end plug just a single bulb) and you can plug the male plugs on top of each other at the outlet. Even if you are stacking plugs for short strings of lights, don’t exceed the max connectivity figure for those strings.  In other words, you can’t install 20 plugs on top of each other. 

This is a stackable plug on a set of craft lights. Notice it’s also “non-polarized” – there isn’t a “fat-prong” side. 

Dimmable. Products that are not rated as dimmable are not suitable for animation.

Maximum Current . The maximum amount of current that this light string can pull.

Voltage Rating. The  specification of the voltage source  for the  light string. On our website the choices are a standard 110/120 V rating or 12 V.

Current draw. The amount of current the light string pulls. .

Power. Total power measured in watts required to operate this string of lights.

Bulb Height. This is the distance from the base to the top of the lens and does not include the base measurement.

Bulb Width. The width of the LED lens as it would be measured across with a ruler or calipers.

Bulb Diameter. Distance around the lens of the bulbs.

Potential LIfespan Estimate. See this article for a discussion of thie specification.

Warranty. Our warranty is 90 days of normal, seasonal use after the delivery of an order.

Bulbs (LED and Incandescent)

Most of the specifications for Bulbs are listed in the list above. Here are the specifications unique to individually purchased bulbs.

Incandescent or LED Indicates whether the bulb is a traditional incandescent bulb that uses a filament to create light or a new-style LED bulb that uses a form of LED to create light.

Bulb Color This is the color of the bulb. For LED lights, this is the color of the LED’s and the lens.

Base Type: Size of the base of the bulb. Use this specification to match the bulb to the right cord. The three sizes most likely to be seen online are E12 (the size of a C7 bulb also known as candelabra), E17 (the size of the base of a C9 bulb also known as intermdiate), and E26 (also known as medium base) which is the larger bulb base size of patio lights.

Shape of Bulbs This is the shape and size of the bulb. C stands for “cone” in C7 and C9 and the G indicates the bulbs are round in G30, G40, and G50. See more about bulb shapes and sizes here.

Base Finish This is the metal that the base of the bulb is manufactured with. Most of the CLS bulbs have nickel over brass bases. Warm white LED bulbs are made with brass bases so they can be distinguished from pure white. (See the photo above to see the different colors of the bases.)

Base finish. The metal finish of the bulb. Nickel indicates nickel over brass.

Dimmable Non-dimmable bulbs are not suitable for animation.

Bulb Diameter The distance in mm or inches around the bulb.

Bulb Height The height of the bulb from the top of the metal threaded base to the top of the bulb

Bulb Width The width of the bulb from the outside to the outside. This is the distance you would measure if you put the bulb on a ruler or measured it with calipers.

Amps Usage. The amount of current that the bulb draws under operation.

Watts. Total power draw for the bulb measured in watts.

Kelvin. For LED bulbs only – and only notes for the SMD Bulbs – this specification is the range of color “temperature” of the bulb.

Lumens. An approximate measure of the brightness of the bulb at 1 meter from the bulb under operation.

Additional specifications for Cords

Wire Color: Color of the insulation. (Note, our insulation is PVC, petroleum based and does not contain soy.)

SPT Rating. Specification related to the thickness of the insulation. (Has nothing to do with maximum current rating, just a measure of thickness and resulting durability of the cord.) Click here to read and article comparing SPT-1 and SPT-2.

Space Between Sockets. This is the distance between sockets. Note that there can be a slight variation in the distance between sockets. Not usually a critical issue, if you are planning to install the cords on a flat roof, consider installing clips on the cord first before securing them in place and with a little “play” between the sockets to reduce stress on the cords.

Head: Distance Between Plug and First Socket. The length of the wire between the male plug and first socket. For some cords, this is quite long and may help you eliminate an extension cord or two.

Tail: Distance between last socket and end of cord. Measurement of the length of the wire between the last socket on the cord and the female plug.

Connection. This specification lets you know how many plugs are or are not installed on the cord. Most commercial C7 and C9 cords are manufactured with only male plugs. Pay close attention to this specification and order gilbert plugs for E12 and E7 cords if required for your project. All spools of cords (greater than 100 feet) do not come with plugs and it is required that you purchase plugs separately in a number suitable for your project.

Current Rating. Measure in amps of maximum current that the cord can pull (or use) during operation. We suggest you don’t exceed 80% of this specification.

Number of sockets. The total number of sockets on the cord or spool. This is naturally also the number of bulbs require to fill the cord.

When working with glass bulbs, consider always ordering an extra box of bulbs to account for breakage during installation.

Shellie Gardner
Aside from throwing dinner parties that feature at least two kinds of cheese dip, Shellie's passions include travel, Mid-Century Modern furnishings and finding the perfect street taco. Has been known to snort laugh champagne.

2 thoughts on “What is that specification?”

  1. I have two strings of white M5 LED Christmas lights (200 count per string). These were marketed by holiday time and sold by Walmart. 48 LEDs are out. They are not all in the same sections. The strings are used indoors and the cords are in excellent condition. I replaced a few of the bulbs over the last two years but I am out of replacements.
    I can’t find replacements of any quantity in any of the big box stores. Are bulbs for these strings available through Christmas Light Source? I don’t like throwing away the light strings, it is a big waste of resources. I don’t mind putting individual LEDs in the correct bases and yes I am aware polarity is important. Your prices for strings of lights are excellent and that will be the way to go in the future. Thank you

    1. Hello,

      I’m sorry but our LED light strings don’t have removable bulbs so we don’t carry LED replacement bulbs.

      You might consider using bulbs from one string to make the other “complete”.

      Also consider that you might have a higher than normal number of surges on your electrical lines that are effecting your bulbs in that way – our first thought when random bulbs are out instead of the entire string. Be sure to plug your LED lights into a surge protector in the future.

      Sorry we couldn’t be of more help with replacement bulbs. Try checking with the company that manufactured your strands.

      (We love to use our LED lights all year as well so we understand about maximizing resources!)

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