EagleLight’s LED University: Bulb Bases and Sockets Explained
In this lesson of EagleLight’s LED University we discuss the naming conventions of LED light bulb bases and light bulb sockets. Details of several types of bases and light sockets are shown in diagrams with dimensions and names.
Naming Conventions of Light Bulb Sockets and Base Types
Light bulb bases and sockets are normally defined by a letter-number-letter format, with the last letter optional. The first letter designates the shape or form of the base, the numbers represent either the width of the base or the distance between the pins. The second letter designates the number of pins or contacts on the lamp. The numbers are normally in millimeters. LED light bulb sockets and bases are manufactured to the same standards as halogen, incandescent and other traditional lights.
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Light Bulb Base and Socket Types
- B Bayonet Collar Base
- E Edison Screw Light Base
- F Single Pin Type Base
- G Multiple Pin Type Light Bulb Base
- K Cable Connections
- P Pre-focused Light Base
- R Recessed Contact(s) Base
- S Shell-type Light Bulb Base
- T Telephone Slide Base
- W Wedge Base
- X Special Type Lightbulb Base
Lamp Number of Pin or Contacts
- s Single Pin
- d Double or Bi-Pin Base Type
- t Triple Pin Base or Tri-Pin Base or 3 Pin Base
- q Quadruple Pin Base or 4 Pin Base
Bulb Type Details
B or Bayonet light bulb base and sockets
BA75, BA95, BA150, BAY150, BA155, BA220
Bi-pin and G light bulb sockets and bases
G4, G5, GU5.3, GU10, G13, T-1/2, T-3/4, T-1, T-1 1/4, T-1 3/4.
E or Edison screw-in sockets and bases
“E” or Edison base types, sizes and names
|Base Number||Diameter||Base or Socket Name|
|E5||5mm||Lilliput Edison Screw Base|
|E10||10mm||Miniature Edison Screw Base|
|E11||11mm||Mini-Candelabra Edison Screw Base|
|E12||12mm||Candelabra Edison Screw Base|
|E14||14mm||Small Edison Screw Base (supports 240V)|
|E17||17mm||Intermediate Edison Screw Base|
|E26||26mm||Medium Edison Screw Base|
|E27||27mm||Medium Edison Screw Base (supports 240VAC)|
|E39||39mm||Mogul or Giant Edison Screw Base|
|E40||40mm||Mogul or Giant Edison Screw Base (supports 240VAC)|
F or Flange light bulb base type and sockets
G, GU, GX, etc. multi-pin light bulb base and sockets
The “G” base type of lamp and light bulb is used to designate a “pinned” base. This can include several pin types and different numbers of pins.
Designation is by letter(s)-numbers-optional letter: The first letters include “G” followed by an optional U, X, Y or Z. Next is a number that designates the number of millimeters between the center of each pin. Finally the optional final letter designates the number of pins, no letter implies 2 pins as does a d for double. Pin number designations include: s : Single, d : Double, t : Triple for 3 pins and q : Quadruple for 4 pins.
Examples include: GU10 base type, G24q base type, or for T8 tubes G13 bi-pin.
|Type||Pin to pin distance||Pin Diameter||Typical Bulbs that use this base|
|G4||4mm||0.65-0.75mm||MR11 and other small halogens of 5/10/20 watt and 6/12 volt|
|G5||5mm||T4 and T5 fluorescent tubes|
|G5.3 GU5.3 GX5.3 GY5.3||5.33 mm||1.47-1.65mm||MR16 and other small bulbs typically using 12/24 volts|
|G6.35 GX6.35 GY6.35||6.35 mm||0.95-1.3mm|
|GU10||10mm||bulbs using twist-lock bi-pin base|
|G13||12.7mm||T8,T10 & T12 fluorescent tubes|
|GU24||24mm||2 and 4 pin bases with center key|
|GX53||53mm||used with puck shaped lamps typically twist-lock|
K or Cable connected lights and lamps
EagleLight uses the designation of K to indicate that a cable is the power connection for a lamp. This designation is EagleLight product specific. So where you see a K used in a base type location in a part number. You can assume that the product is a wired connection to power.
P or Pre-focused lamp base and sockets
S.C. Prefocus and D.C. Prefocus
R or Recessed lamp base and sockets
S or Slide light bulb base and sockets
W or Wedge light bulb base and sockets
D.F Wedge and S.F. Wedge sockets.