Recommended Load on Smart-UPS 1500RM

[Anonymous user]

First post here,

I've inherited the job of looking after the network here and in our rack we've got a Smart-UPS 1500RM that currently has plugged into it - 2x 48-port switches, a Cisco ASA-5510 firewall, a Barracuda Message archiver (small 1U firewall-sized device), an IBM DS4700 SAN with 13 SCSI drives, a Dell Poweredge 2U Rack mount server and a 17" LCD monitor.

We are going to be adding another 2U Dell rackmount server for our backups, and I am concerned with putting too much load onto the UPS. The load is currently at 60% judging from the lights on the front. The last time I needed to add one of the switches and was out of plugs on the UPS, the guy who originally installed the UPS said to just add a 16-plug power bar to give me more outlets.

My question is, how can you judge when you've got too much plugged into one UPS and it's time to add another UPS into the mix? Is there some rule of thumb that is used?

Much appreciated.

[BillP]

generally, at APC, we recommend no more than 80% load. that helps you account for in rush current or a little extra power draw during peak usage times on your equipment but under normal circumstances, 80% what you should see.

you need to keep in mind your required runtime. a power bar (PDU) may give you more outlets but it certainly does not add to the watts/VA capacity of the UPS. the UPS can become overloaded of course with too much load and it could possibly turn off of or be running at 100% and then when a power outage occurs, it will provide far less runtime than you probably desire.

ultimately, i think you need to find out how much more power the server you want to add will draw and then lets calculate that into what you currently have.

i assume you are not using an powerchute software or UPS Network Management Card with this device so we can log in and see the exact load percentage on the unit? in the user's manual here, it tells you about the load bar graph on the front that you estimated.

hope that helps.

[Anonymous user · Accepted solution]

So if I read the manual correctly, 3 of 5 lights on the front indicate 50% load currently, which of course affects the runtime. Judging by what I already have, I don't think that adding a 2U rackmount server will reduce the runtime by too much, but does the UPS actually monitor the current being drawn? I just don't want to power up the server and end up tripping a breaker somewhere because I'm drawing too much current on the same circuit, and end up killing power to all that equipment. I'm hoping for someone with some server rack experience to give me what they would consider to be a reasonable load on a UPS before they would add an additional one.

Thanks!