The question has arose today on the proper connection for these power supplies.

Two power cords exist of each of the power supplies with the Cisco WS-C6509 having two of these power supplies.

We have an APC to provide battery backup for a short period during power hits or bumps, but how should the cables be plugged in.

TWO SOURCES

1.) WALL/HOUSE Power

2.) UPS (Battery Backup)

OPTION A

PS1 - Cord1 --> WALL

PS1 - Cord2 --> UPS

PS2 - Cord1 --> WALL

PS2 - Cord2 --> UPS

* The thought here would be that both power supplies would remain working if WALL or UPS power failed.

OPTION B

PS1 - Cord1 --> WALL

PS1 - Cord2 --> WALL

PS2 - Cord1 --> UPS

PS2 - Cord2 --> UPS

* The thought here would be that one power supply would have its full capacity while the other power supply would be down.

So which is the correct answer?

Researching Cisco.com now for some answer.

Interesting information taken from this link on Cisco's website

When 6000W power supply is used with the chassis Catalyst 6506, 6509, 6509-NEB, and 6509-NEB-A, it operates at 4000W maximum output. It operates at 6000W maximum output when it is used with Catalyst 6506-E, 6509-E, and 6513.

After reviewing the chart above, I believe OPTION B is the correct choice because if either cord on the power supply changes from the required 220VAC, 16A, the output power will drop from the 6000w to 2900W.

So if your switch is configured like stated in OPTION B

OPTION B

PS1 - Cord1 --> WALL

PS1 - Cord2 --> WALL

PS2 - Cord1 --> UPS

PS2 - Cord2 --> UPS

You will maintain 6000W if one source fails (WALL or UPS).

This has occured again and again.

A Cisco 6000w power supply is not redundant at 6000w if the power cords from one power supply go to different power sources.

Power Supply 1 (PS1) must have both power cables go to the same power source (example: HOUSE POWER)

Power Supply 2 (PS2) must have both power cables go to the same power source (example: UPS)

If you mix the two cables from one power supply then the output power will reduce down to half the power for the entire switch if only one power source goes down.