To date, there are many sizes and types of lamp base caps, which we will now talk about in more detail.
- marking
- characteristic Exceptions
- Popular
Marking
The oldest type is the threaded type that was invented by Thomas Edison at the end of the 19th century( index E).In addition, there are the following markings of lamp caps:
- G - pin;
- R - with recessed contact;
- F - with one pin( a - cylindrical, b - corrugated, c - special shape);
- B - pin;
- S - Soffit;
- K - with cable connection;
- P - focusing;
- H - for xenon bulbs;
- T - telephone;
- W - current inputs are located in the glass of the bulb itself.
We draw your attention to the fact that in addition to one of these letters, one more can be attached: U, V or A, which means, respectively, for energy-saving lamps, with a conical end or automotive type.
The following is a numerical marking showing the diameter of the cap or the distance between the two pins,( in mm).After the figure, the number of connections( flexible, plates or pins) can be indicated. For this, the letters s, d, t, q, p are used, which means 1, 2, 3, 4 or 5 contacts.
products Now let's take a closer look at the main characteristics of all household types of lamp base caps and the conditions for their use.
Characteristic
Threaded( E). Despite the fact that it appeared the very first almost a century and a half ago, its popularity has not lost its popularity until today. This is due to a simple and convenient design that allows you to screw the flask in just seconds. Now these types of socles can be installed in all types of light bulbs: LED, halogen, luminescent and, of course, incandescent. As for the types of threaded bases, they can have the following diameters according to GOST: 5 mm( E5), 10 mm( E10), 12 mm( E12), 14 mm( E14, mignon), 17 mm( E17), 26 mmE26), 27 mm( E27, conventional), 40 mm( E40).At home, usually less than E14 is not used.
Pin( G). Usually used in halogen, LED and fluorescent light sources. The design is represented by pins, which are also easily and quickly connected to the network. The variety of products lies in the distance between the pins, as well as their number. For example, type G4 means that the distance is 4 mm, and G5.3, respectively, 5.3 mm. The disadvantage of this design is that it will be difficult for an electrician-novice to determine the size of the socle to buy( for example, when the fluorescent lamp goes out of order), so you will have to go to the store with a broken example. 
With recessed contact. This type of lamp socket is used in lighting with tubular quartz and halogen light sources that have a high heating and power temperature.
We draw your attention to the fact that in the marking of these products there may be a figure( for example, 118).It means the total length of the whole product.
Soffit( S). This type is most often used for lighting installation in the bathroom, as well as for lighting mirrors. The designation S6 or S8.5 means that the body diameter is 6( 8.5) mm.
Pin( B). This type has the principle of operation similar to the threaded one. The only difference is that a thread is required for a threaded connection, and in this case two pins are installed opposite each other along the outer diameter of the socket. This design makes it easy to connect the lamp to the network. The main application is automotive lighting. Marking is carried out as follows: BA - pins are installed symmetrically, BAZ - one of the pins is displaced along the radius and height, BAY - the displacement occurred only along the radius. The figure indicates the diameter of the housing in mm.
Focusing( P). Its design is represented by a lens, with which the light flux is focused( an unusual shape is seen in the photo).Most often this type of socle is used in automotive lighting, as well as in floodlights and street lamps. The digital marking indicates the diameter, in the place where the lamp is installed, or the size of the flange that focuses the light flux.
Telephone( T). Can be used to illuminate electrical appliances in the car, as well as for signal lights in automatic control panels. The marking is digital, it shows the width of the contact plate( in mm).
As for the rest, they are used extremely rarely, and the marking itself may even be missing. In this case, the type of the lighting lamp itself is indicated, along which the size and type of the socle are determined.
Exceptions to
As we have already said, some of the types of lamp caps may lack marking, instead of which the designations will only be on the light source itself. In this case, you can determine the size only by marking the product.
To your attention the main markings:
- MR16 - halogen lamp, which has a reflector. In it, as a rule, a pin base( index G) is installed.
- R50 - reflex, with threaded retainer in the plafone( E).
- 2D - LED( KLL), which has pins for connection.
I would also like to pay attention to linear fluorescent lamps. The diameter of their tube determines the size of the cap. There are tubular flasks having the standard sizes T5, T8, T12 and T15, the diameter of which is equal to: 1.59 cm, 2.54 cm;3.17 cm, 3.80 cm
Popular
For incandescent lamps, the most popular are 2 types of threaded bases: E14( mignon) and E27( standard).
For spotlights, a pin is used( GU10 or G13) and threaded( E14 and E27).
The device of a fluorescent lamp can include such types of socles as G13, G23, G24, G53.
Halogen bulbs most often use the sizes G4, G9 and R7s( the latter option is installed in quartz light sources.)
G9 
G4 Here you have got acquainted with the existing types and sizes of lamp bases. We hope that the information was available, and most importantly - useful!
Also read:
- How to unscrew the cap of the bursting bulb
- How to make an LED lamp with your own hands
- How to hold a light in the house
