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E27, E14, G4, GU10, B22... What is it? These references are simply the "family names", if we can say so, the caps of the bulbs! So do not shyness, show... base and get to know until... base these lamps that illuminate our lives!

A little vocabulary: lamp, bulb, base, socket, etc.

Regardless, we use the words lamp or bulb for each other. Yet, these are two totally different elements.

According to the Larousse dictionary, a light bulb is a « lighting device, consisting of a transparent or translucent envelope, gas-tight and enclosing a luminous body ". The lamp itself is a " lighting fixture... »

In fact, the bulb is the place where "light" is "made" either by means of a filament (incandescent halogen or compact fluorescent bulb) or by an optoelectronic process (LED bulb).

The bulb (or bulbs in the case of an LED lamp) is protected by the lamp. This one is connected to the electric circuit thanks to the base which comes attach to the socket. There are different types of base to which specific sockets correspond. No more than the dishcloths and towels, the sockets and the shells are mixed together. And electricity hacks are strongly discouraged...

The different types of caps of lighting lamps

Fortunately, so that we can locate easily, the measurements of the sockets and caps are standardized: E27, E14, G4, GU10, B22, etc.

The letters indicate the type of pellet. For domestic lighting, the main available caps and their codifications are:

  • E for screw base. It is the one invented by Mr. Edison himself, hence the letter E!
  • B for bayonet base.
  • G for pin base.
  • R for base with recessed contacts.
  • S for smooth cylindrical base.

The numbers indicate the diameter of the bushing or the inter-axis measured in millimeters.

The most common uses of different caps

For example E14 and E27 are screw caps having a diameter of 14 or 27 mm. With the B22, bayonet caps 22 mm in diameter, these are the most used in our luminaires. They equip both halogen, compact fluorescent and LED lamps.

A special mention for the "mignonnette" who is the little pellet screw torches. Today, less poetically, she is known as E10. In contrast "Goliath" or E40 is the big base of 40 mm high-power lamps for public lighting.

In the bayonet family, some stand out by having 1 or 2 pads (S or D). The stud is the metal piece through which the electrical contact is established. BA15S, for example is the bayonet bulb with a base of 15 mm with a single stud, brake lights of your car. While BA15D, with the same bayonet but with two studs, is that of your backup lights.

Since the appearance of halogen bulbs and LEDs, pin caps (G4, G5.3, G6.35, GU10) have become more common. Previously, they signed the fluorescent tubes with their G5 or G13 caps at the ends. The GU10 socket and that of halogen or LED lamps with a reflector.

It should be noted that the pellet G5.3 is the French siamese brother of the MR16 of the international codification.

In the halogen family, R7S refers to the two bases of the pencil bulbs that made the halcyon lamps of the 80s look good and that you can react with economic halogen bulbs or with LED bulbs for a lower consumption.

With all these explanations, we are no longer base, these bad students who sleep in the back of the class!


Video Instruction: Different Types of Lamps LED, CFL, Halogen, Tungsten Filament, Bayonet Cap & Edison Screw (Bulbs)