What Is A Standard Light Bulb Base?

Light bulbs come in different shapes, sizes, and bases too, but what is a standard light bulb base? A standard light bulb base is the most common bulb base type used in the U.S. and other countries with 120V AC. It’s also known as “E26.” We gathered all information about the standard light bulb base (E26) in this article. So, keep scrolling.

What Is an E26 Bulb Base?

Most light bulbs used in U.S. households, no matter what type they are, come fitted with an E26 bulb base. That includes most incandescent, LED, CFL, nostalgic, and halogen light bulbs.

You can recognize the standard E26 bulb base from stereotypical images of light bulbs. Whether in cartoon illustrations or mobile phone emojis, this type of bulb base is widely common.

That said, a light fixture will only work if fitted with a socket compatible with its bulb base. That’s why it’s quite essential to know what base size you’re looking for.

Where Did the Name Come From?

The letter “E” in the name refers to Edison screw. This type of fixing method got its name from Thomas Edison, the person behind the invention of the incandescent light bulb. As for the number “26,” it indicates the base’s diameter in millimeters (26 mm is a tiny bit over an inch).

Having said that, this type of base is also commonly called a Medium Edison screw (MES).

What Is the Standard Size of an E26 Light Bulb Base?

According to the International Electrotechnical Commission (IEC), you can find the dimensions of the E26 bulb base defined under standard 7004-21A-3. With a height of 1.05 inches and a width of 1.03 inches, the E26 bulb base fits most light fixture sockets.

The following are the minimum and maximum standard E26 bulb base dimensions:

  • Height with solder (T1): min 19.56 mm
  • Height without solder (T): min 19.56 mm
  • Height of contact point (C): min 3.25 mm
  • Width of contact point base (H): min 9.14 mm and max 11.56 mm
  • Width of the contact point (L): min 15.24 mm and max 17.01 mm
  • Thread radius (r): 1.191 mm
  • Thread height (d1): 24.72 mm

How To Recognize It?

There are a few ways to know what type and size of bulb base you’re looking at. Here’s what to do to figure it out:

1. Check the Packaging

Normally, you can find all the details about the light bulb printed on the box, including the wattage, bulb size, base type, etc.

2. Check the Bulb Itself

If you don’t have the packaging in hand, it might help to check the light bulb. Sometimes manufacturers print the brightness, wattage, and base type directly on it.

3. Inspect and Measure the Bulb’s Base Diameter

Generally, a standard light bulb base would be metallic with screw threads that measure approximately an inch in diameter.

How Does the E26 Light Bulb Work?

The E26 bulb base works just like all the types of light bulbs using the Edison screw style. Once you align the lamp’s screw with the fixture socket, all you need to do is rotate it clockwise until completely secured.

Not only do the screw threads help fix the bulb into place, but they also act as electrical paths. As for the contact point at the base of the screw, it represents the live electrical input.

Leading to the filament inside, in the case of an incandescent bulb, there are electrical wires welded to the contact point and screw threads. When it comes to LED and CFL bulbs, those wires connect to internal electronics.

Why Is the Standard Light Bulb Base Better?

There are a few advantages to using the standard light bulb base, E26, including:

  • Availability: Since the E26 is the most common type of light bulb base, you can easily find it at all electrical stores.
  • Compatibility: It fits in almost all light fixtures in the market because it’s widely used across the U.S.
  • Ease of Use: Installing a light bulb with an E26 base is quite easy and straightforward, as it doesn’t require any special tools or skills.
  • Strength: The Edison screw style makes the E26 light bulb more secure in place, which is a huge plus in places with high vibrations.
  • Safety: The tight fit that the screw base of the E26 light bulb creates prevents any debris or moisture from reaching the contact point, which means less electrical failure possibility.

What Are the Most Common Light Bulbs With Standard E26 Bases?

Most lamp types come with the standard E26 base because it, as previously mentioned, is quite common. These light bulbs include:

  • A15, A19, and A21 (A-shaped bulbs)
  • PAR16, PAR20, PAR30, and PAR38 (Parabolic Aluminized Reflector spotlight and flood light bulbs)
  • G16.5, G25, and G30 (Globe-shaped bulbs)
  • BR20, BR30, and BR40 (Bulged Reflector spotlight and floodlight bulbs)

What Are Other Types of Edison Screw Base Light Bulbs?

The standard E26 light bulb base isn’t the only Edison screw (single contact) lamp base out there. In fact, there are many other types of Edison screw style bulb bases, which include:

  • Intermediate (E17) with a diameter of 17 mm
  • Mogul (E39) with a diameter of 39 mm
  • Miniature (E10) with a diameter of 10 mm
  • Midget (E5) with a diameter of 5 mm
  • Candelabra (E12) with a diameter of 12 mm
  • Mini Candelabra (E11) with a diameter of 11 mm

What Are Other Light Bulb Base Styles?

Aside from the ordinary Edison screw, there are many other mounting styles for light bulbs, which include:

1. Pin Base

The concept of the pin bulb base hugely differs from the ordinary Edison screw. Instead of two wires connecting the voltage to the lamp, the pin base uses metal pins sticking out of it. Those pins directly connect the lamp to the electrical voltage.

There are Single pin, Bi-pin, and Four pin bulb bases. Each one of those bases works by inserting its pins into the fixture’s socket.

This type of bulb base includes but isn’t limited to:

  • Miniature Bi-pins that are used in T5 linear fluorescent bulbs
  • G12 (Used in T9 HID bulbs)
  • Medium Bi-pin G13 that’s used in T8, T10, and T12 linear fluorescent bulbs
  • Single pin Fa8
  • Recessed Single Contact (RSC) R7S that’s used in T9 HID bulbs
  • Recessed Double Contact (RDC) R17d
  • G23, GX23-2, G24Q-2, and GX24Q-3 used in compact fluorescent bulbs

2. Twist and Lock Base

This is also a double-pin type. However, you install it by inserting the pins of this bulb base into the light fixture socket holes and twisting it to lock it in place. The twist and lock bulb base type includes the following:

  • GU10
  • GX10
  • GU24 (only used in CFL, CCFL, and LED bulbs, which are energy-saving)

3. Bayonet Base

This type is most commonly used in many parts of the world, including the UK, India, Australia, and Ireland.

The bayonet bulb base has two pins on opposite sides of the cap. Sometimes it has three of them in more specialized bulbs, like electric radiative heater fire glow bulbs and mercury street lamps.

Moreover, this type of bulb base is usually abbreviated to BA followed by a number representing the diameter of the base.

Here are a few examples of bayonet base bulbs:

  • Miniature bayonet
  • Double Contact bayonet (BA15d)
  • Single Contact bayonet (BA15s)
  • Index Double Contact bayonet

4. Wedge Base

You can see this type of bulb base in small light bulbs and the way it works is kind of similar to the Bi-pin base type. The difference is that the two pins for these bulbs are the ends of the same wire running inside the light bulb.

These wires are usually inserted into a wedge-shaped plastic base used to mount the bulb. This ensures a tight connection to the socket. Therefore, this bulb requires straight in or out force to install and remove. Unlike many other bulbs, it doesn’t require any kind of rotating.

Types of these wedge base bulbs are often called:

  • Wedge
  • Wedge D.F.
  • Wedge S.F.
  • RX7s
  • Slide
  • Wedge Subminiature

5. Specialty Base

Those types of light bulb bases are mostly made for more specialized uses. For example:

  • Rigid Loop: Used in interior automobile lighting, under cabinet, and accent lighting
  • Metal Clip: You can see it in linear halogen heat lamps used in dehydrating, curing, warming, and drying food application
  • PGJ5: Seen in metal halide bulbs used in commercial and retail spaces
  • Side Prong: These are more common in food service applications
  • Festoon: Used in xenon capsule bulbs that are also perfect for under cabinet and accent lighting
  • Three Contact Lugs: Used on sealed beam automotive headlights
  • Mogul End Prong: Mostly seen on bulbs used for high-ceiling applications, like in banquet halls, auditoriums, convention centers, exhibits, etc.

6. Cable Base

This type of light bulb often ends with two cable connectors forming what’s called a cable base. These cable ends have three types, which are:

  • Flat male
  • Flat female
  • PK30d