Diversity - Data Switches, etc

[Keri_WW]

In a building with (2) Fiber Switches, (21) Network Switches, and (21) Card Reader Controllers, do you think there could be any diversity on this equipment?

All of this combined has a connected load of about 300A and the owner wants it connected to an existing emergency backup generator. Without some diversity the added loads would be too high.

 

[wireguru]

I wouldnt think so. BUT is this 300A based on nameplate rating, or is this what the equipment is actually drawing? The larger switches that use alot of power (such as cisco 6500) will tell you how much power theyre drawing

 

[Keri_WW]

These were all #'s given to me buy one of the building IT guys. The network switches are Cisco 2960 series which consume about 1.5-3 amps (as shown on product cutsheet).

 

[zbang]

Don't believe the nameplate ratings here, a cisco 2600-series is probably under 100w (I don't have one handy here to meter). Unless the fiber switches are 'enterprise' ones, that entire pile is very likely under 10kw.

Is this stuff on a UPS (if not, why not)? That might give you some idea of the actual load v. the nameplate load.

 

[Keri_WW]

Well I don't really understand why this stuff (aside from the card readers) needs to be on emergency power. Who is going to need data when everything else in the building is out?

Basically my issues are that my gen feeds an ATS which feeds a step-down xfmr which feeds my emergency panel. If that load is accurate, I will have to get a larger panel, a larger xfmr, and a larger breaker ahead of the xfmr. These items have already been ordered and partially installed... thus the need for an accurate load and diversity (if one exists).

 

[zbang]

Well I don't really understand why this stuff (aside from the card readers) needs to be on emergency power. Who is going to need data when everything else in the building is out?

Why? Computers/IT equipment can easily develop software-related problems when not properly shut down- like loss of documents & other work, hard disk errors, etc. For this reason, all IT loads should be on a UPS. If the environment requires continuous operation, then the UPSs need to be covered by a generator so they don't run down. If not, then the systems need to be configured to automatically perform a clean shutdown when power is out for more than, say, 5 minutes. (All this is entire business dependent- if the business can survive the accounting system being out of commission for a day or two, don't bother with the UPS....)

These items have already been ordered and partially installed... thus the need for an accurate load and diversity (if one exists).

Just like a anything else, you can't just add the nameplate ratings to get the real load. Absent actual measurements, you'll have to either guess or go on someone else's guess. My guess, based on what I know about this is under 10kw. (Look at it this way, each card reader is probably on a 50 or 75va transformer. There's no way that's going to draw 150w continuous.) Likewise, an electric strike plate for a door,depending on type might be 20w continuous or a 50w impulse.