IEC 60061-4 pdf download Lamp caps and holders together with gauges for the control of interchangeability and safety – Part 4: Guidelines and general information
3.3 Part lc) of a designation consists of lower case letters indicating the number ofcontacts, plates, pins, etc. or flexible connections.
The following code letters are used in this group:
s- for one contact
d- for two contactst
– for three contactsq
– for four contactsp
– for five contacts
The shell of a cap shall not be considered as a contact regardless of whether it is a currentcarrying component or not. The contacts need not be of the same shape.
Examples:E26d – an E26 cap having two bottom contacts
G10q – a cap having four contact pins.
3.4 Part (d) of a designation, if necessary, consists of symbols preceded by a hyphen toindicate additional elements that are important for interchangeability (e.g. a number 3 for a3-pin bayonet cap or an indication number for a key configuration).
Examples:B22d-3- a B22 cap having three locating pins.
PG22-6.35 – a prefocus cap having a collar of approximately 22 mm diameter andtwo contact pins with a spacing of approximately 6,35 mm.
3.5 Part (e) of a designation consists of numbers immediately following an oblique stroke toindicate the approximate overall length of the cap expressed in millimeters. This length includesprotruding insulation but excludes the height of contacts or pins.
Example: B15d/19- a B15d cap having an overall length of approximately 19 mm.
3.5.1 The length of an SV (festoon) cap is measured between the open end of the shell and acircle of 3,5 mm diameter on the cone.
ln order to avoid misunderstanding, this length is stated behind a hyphen but before the obliquestroke if used.
3.6 Part (f) of a designation consists of a number for caps having a skirt or spun-in shell.Anumber in the lf group
position is preceded by the multiplication sign (x) in the designation.The number indicates theapproximate outside diameter of the skirt (excluding any flare) or the inside diameter of theopen-end, in millimeters.
Example:B22d/25×26 – a B22 cap having an overall length of approximately 25 mm and an
outside skirt diameter of approximately 26 mm.