Contact US

Log In

Come Join Us!

Are you a
Computer / IT professional?
Join Tek-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Tek-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

How to size a UPS for PoE switches

How to size a UPS for PoE switches

How to size a UPS for PoE switches

We would like to provide really clean power to the switches that are connected to our IP phones.  What formula should we use to calculate the load requirement for a number of power over Ethernet (PoE) network switches?

Most engineers take the maximum load capacity of the switch and multiply that by the number of switches.  This is not a call center, so it is very unlikely that even 5 percent of the phones will be in use at one time.  Since the phones are the only devices using the PoE, it is likely that we will never need the full amount that the switches.

Most of the calculators on UPS vendor sites suggest around 125 Watts per switch.  The switches themselves have a maximum output of ~450 Watts.  Due to the cost of UPS units, I really do not want to over build this solution.

Any suggestions would be appreciated, especially from those who design VoIP solutions.

RE: How to size a UPS for PoE switches

If its just for access switches have you considered a Cisco RPS ?


Fatman Superstar (Andrew James)


Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Tek-Tips Forums free from inappropriate posts.
The Tek-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Tek-Tips forums is a member-only feature.

Click Here to join Tek-Tips and talk with other members! Already a Member? Login

Close Box

Join Tek-Tips® Today!

Join your peers on the Internet's largest technical computer professional community.
It's easy to join and it's free.

Here's Why Members Love Tek-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close