Cisco Catalyst 4500 and UPS recommendations

We’re in the process of implementing a Catalyst 4510-R-E switch for a customer, and they are looking for recommendations on sizing a UPS.   Specifically, this is a redundant Supervisor (WS-X45-SUP6-E) in an E-series chassis, and w/ five (5) 48-port PoE line cards (WS-X4648-RJ45V+E).  Running it through the Cisco power calculator, it comes up with a total output power of 4226W, and a “typical” output power of 3380W.  They outfitted the switch with dual PWR-C45-6000W power supplies for redundancy.

The customer is now needing to know exactly how much capacity will really be required in a UPS to handle this.   I’m no power expert, but I’m assuming that even though one of these power supplies seems sufficient to handle the complete load, the 2nd power supply will also be “up and operational”, so that it can take over in case of a primary failure.  So, several questions:

1)      Is the current demanded load split between the two power supplies, so that each would be live and providing about half of what is demanded, or is everything drawn from the primary until it fails or is removed?  

2)      Is how the power supplies are used a configurable option on the Catalyst 4500?

3)      Most importantly, how big a UPS will be required to handle this entire chassis, and keep BOTH power supplies up in whatever state they require?    Will a 6Kv UPS be sufficient?  (I’m asking because even if one power supply was operating at capacity, the 2nd one will still be drawing some additional power.)

Thanks, folks.