scope:

This standard covers specifications for all sizes of Edison- type screw-shell lamp bases, both as separate bases and also in their final form as mounted on finished lamps, and for the corresponding sizes of screw-shell lampholders. Also included are the necessary gages used to check the dimensions of the bases and holders. The intent of this standard is to ensure the proper engagement and fit of the base and the holder and to provide for the interchangeability of bases or holders of a given type and size.

The dimensional information provided for the threads of the medium (E26) size of base and holder is also applicable to screw-plug fuses and fuseholders.