LED Lamps socket GU4
People often get confused between illuminants with GU4 and G4 sockets. Not only are the names very similar, but the dimensions with a pin spacing of 4 mm also seem identical at first glance. GU4 and G4 sockets are both present in low-voltage halogen lamps and are the next smaller versions of the GU5.3 type.
Contacts of the LED lamp socket GU4
The contacts of the GU4 socket have a diameter of 0.95 to 1.05 mm. The "U" stands for the U-shaped cross grooves. A spring in the lamp socket engages from both sides, ensuring reliable hold and electrical contact. The pin spacing of 4 mm in the G4 socket is the same as in the GU4 socket, but the two differ because the former does not have the U-shaped groove on the illuminant. The contacts of the G4 socket (0.65 to 0.75 mm) are also slightly thinner than those of the GU4.
For the most uniform possible light output
Both GU4 and G4 sockets are usually combined with MR11 reflectors with a diameter of 11/8 inch (MR35 if specified in millimetres). They are used wherever space is limited and the large GU5.3 and MR16 (MR51) solutions do not fit, for example in designer ceiling lights or in recessed solutions - not only in furniture but also in extractor hoods above the stove, for example. Table lamps, desk lamps and camping lamps in caravans and mobile homes are also equipped with GU4 or G4 sockets. When buying these, make sure that the reflector has the right dimensions and that the light output is as uniform as possible.