STANDARDIZED RELAY — Type / case-colour reference table
EL-4spec tableUnverifiedPin-layout text in the rightmost column is paraphrased from the small visual diagrams; pin-pair adjacencies on Pass 2 may need touch-up.
Standardised relay — type vs case-colour vs connector pin layout
1T
Pin numbering (outer view)1, 2, 3, 4, 5
Internal circuitCoil 2↔3; transfer contact 1↔(4 or 5)
Connector pin layout (unit side)Top: 1↔4 changeover; bottom: 5/3, coil pin 2
Case colourBLACK
1M
Pin numbering (outer view)1, 2, 3, 5
Internal circuitCoil 2↔5; make contact 1↔3
Connector pin layout (unit side)Pins 1/2 above, 5/3 below
Case colourBLUE
2M
Pin numbering (outer view)1, 2, 3, 5, 6, 7
Internal circuitCoil 2↔7; two make contacts 1↔3 and 6↔5
Connector pin layout (unit side)Pins 2/1 above, 6/3 + 7/5 below
Case colourBROWN
1M-1B
Pin numbering (outer view)1, 2, 3, 4, 6, 7
Internal circuitCoil 2↔7; make 1↔3 + break 4↔6
Connector pin layout (unit side)Pins 2/1 above, 6/7 + 4 below
Case colourGRAY
NOTE
Use the case colour to identify the relay type at a glance: black = 1T (transfer), blue = 1M (single make), brown = 2M (double make), grey = 1M-1B (make + break).