DEC NEMA Power Connectors

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This page has some information about the power connectors used in DEC PDP-8 and PDP-11 equipment.

110V AC

For 110V AC, DEC uses the standard 3-prong U.S. power connector. This is known as the “NEMA 5-15” standard.

The plug is a NEMA 5-15P and the receptacle is a NEMA 5-15R.

Looking into the receptacle with the round Ground pin at the bottom:

  • The wire for the Ground pin is Green
  • The rectangular pin on the left is Neutral (sometimes the slot length for this pin is slightly larger than the Hot pin). The wire colour for Neutral is White
  • The rectangular pin on the right is Hot (Active). The wire colour for Hot is Black

240V AC

For equipment distributed in Australia (where our single-phase mains power is 230VAC), DEC used the “NEMA 6-15” connectors.

This is a 3-prong plug (similar in dimensions to the NEMA 5-15 series) except that the two flat pins are horizontal instead of vertical.

The NEMA 6-15 was not designed for use on single-phase power systems. For this reason it does not have “Hot” and “Neutral” pins. Instead it has two Hot pins and NO Neutral. In the U.S. it is typically 208V AC (when connected to 2 phases of a 3-phase supply), or 120V AC (when connected to a “split-phase” supply).

Looking into the NEMA 6-15 receptacle with the round Ground pin at the bottom:

  • The wire for the Ground pin is Green
  • The rectangular pin on the left is used by DEC for Neutral. The wire colour is Blue
  • The rectangular pin on the right is used by DEC for Hot (Active). The wire colour is Brown