E27E26

E27E26 is an informal term used in the lighting industry to describe components, bulbs, or fixtures that are marketed as compatible with both E27 and E26 Edison screw bases. It is not the name of an official standard, but rather a shorthand used by manufacturers and retailers to indicate cross-compatibility in certain products or packaging.

Background and technical notes

E27 and E26 refer to screw-base sizes commonly used around the world. E27 has a 27 mm outer diameter, while E26 has a 26 mm diameter, with a similar screw thread pitch. The slight diameter difference means that not every bulb will fit every socket reliably, and fit can depend on tolerances in the socket, lamp holder, or bulb. To achieve genuine dual-base compatibility, products may employ mechanical adapters, ring spacers, or specially designed bases that tolerate both sizes. In practice, true dual-base bulbs are relatively uncommon, and many “E27E26” offerings are adapters or fixtures advertised as accommodating either base with caution about fit and electrical compatibility.

Applications and safety considerations

Dual-base solutions are most commonly used in mixed-installation environments, such as households or retail settings where both regional standards exist. Important safety considerations include ensuring the bulb’s voltage and wattage match the fixture’s rating and the regional electrical supply (for example, 120 V in North America versus 230 V in many other regions). Although base compatibility addresses mechanical fit, electrical compatibility and certification rely on manufacturer specifications. Users should read product guides and comply with local electrical codes.

See also

Edison screw base, E26, E27, light bulb adapter, lighting standards.