Since no earth contact is required in plugs and sockets of rated voltage up to 50 V, two keyways instead of one are provided the collar. They are accordingly termed the major and minor keyways. The major keyway is always in the 6 o‘clock position. Depending on voltages and frequencies, the minor keyway is always in accordance with table 103 taken from EN 60309-2:1999 + A1:2007 + A2:2012, standard sheet 2-VIII (and in the following drawings).
Drawing: receptacles and connectors U = 40 to 50 V, 50 to 60 Hz, minor keyway in 12 o‘clock position
Rated operating voltage V | Frequency Hz | Clockface position of keyway (major keyway = 6 o′clock) |
20 to 25 | 50 and 60 | no minor keyway |
40 to 50 | 50 and 60 | 12 |
20 to 25 and 40 to 50 | 100 to 200 300 400 > 400 to 500 DC | 4 2 3 11 10 |
25 | DC* | 8 * for portable electrical incubators – use with 12 V or 24 V direct-current voltage in ambulances or helicopters. |
Positions 1 and 9 are reserved for future standards. For design reasons, positions 5, 6 and 7 are not available for use.
If the rated operating voltage is indicated by a colour coding in addition to compulsory markings, such colour coding must be in accordance with IEC 60309-1:1999, table 2:
Rated operating voltage | Colour code | RAL* |
20 to 25 V | violet | 4001 |
40 to 50 V | white | 7035 |
* RAL determined by MENNEKES, as in EN 60309-1:1999 no specification is provided for.