I.T. equipment PDU plugged into UPS

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I'm having an issue at one site where a building engineer is demanding removal of power strips from all UPS units. I'm totally on-board with this, as the cheap plastic power strips are:


  1. not durable
  2. aren't supposed to be mounted (RPTs)
  3. predictably handle the loads -- they're all wired differently depending on the OEM and the price of the device. I've seen some with 14AWG that shouldn't carry more than 10A, but are crammed full of plugs.

The existing UPS units are 2200VA, 3000VA, 5000VA. We can read the power usage from the network gear...nowhere near loading it up. The UPS are running at less than 50% capacity. The runtime is only to carry the load until the site generators kick in, usually within a few seconds.

I'm proposing buying APC or TrippLite rack-mount PDUs that are rated for the network and server equipment, up to 15A and 20A.

The problem is, the site engineer is claiming that this is "daisy chaining" of a power strip off of the UPS. He made reference to a recent inspection, but I reviewed the official documents post-inspection, and the only dings for IT equipment were in general office areas, with 1 instance of an extension cord being used, and 1 instance of two power strips being daisy-chained. No mention of the racked up equipment.

The PDU manufacturers recommend connection to:
  1. a battery protected circuit (centralized UPS with hardwired receptacles at each rack)
  2. a local UPS receptacle
  3. direct to mains power (only some models)

The site will incur many thousands of dollars to buy additional local UPS units with enough receptacles to accommodate all equipment to be directly plugged in.

In addition, there will be the labor and materials for additional breakers, conduit, and receptacle installation for these new UPS units to connect to the e-power panels that are generator-backed.

Am I supported by an "ITE" designation, like UL 60950? Unfortunately, I don't have access to UL.com or the publications.

The NEC citation I've seen for daisy-chaining is for RPTs. A UPS unit isn't an RPT. The PDU _might_ be considered an RPT by people not working in IT.

But, every server room and datacenter uses PDUs to distribute power from a remote UPS to closer to the actual equipment. Otherwise, we'd have to have twice as many UPS units, and 15-20-foot power cords for all of the equipment to reach the UPS without extensions.

A little help here? At this point, the local I.T. staff is giving up to the stubborn engineer. Seems like a huge waste of money and wiring when $100-200 PDUs can do the job.

Sorry for the long post.
 
IMHO the "site engineer" is full of it. For one, "daisy-chaining" usually refers to one power strip (RPT- UL1363) or extension cord into another. The UPS is treated as a supply receptacle, not an extending device, so a PDU (UL 60950-1) coming off the UPS is acceptable practice.

Different equipment, different rules.
 
success

success

After a lot of back-and-forth with bosses in the middle via email and text message...ordered the PDUs and convinced everyone I was trying to comply smartly, without wasting money that is in short supply.

We have now installed UL 60950-1 listed PDUs, which are plugged into the UPS units, which are plugged into the e-power outlets on the wall.

We had a meeting at the site in the MDF...more of an ambush...as me and a local site IT guy were cleaning up cables. The site IT director, corporate CIO, site engineer, and director of another department affected by the inspection all walked into the room. The engineer kept saying that even if I was technically correct, we are now encouraging overload of the circuit because we are increasing the number of outlets. Since it's his job to maintain safety, he still didn't like it.

I took the engineer to the UPS and showed him that we had a load meter with LEDs. I also explained that we (in I.T.) never intentionally load a standalone UPS to more than 2/3rds. Normally, less than 40%. It's for run-time. Even though this site has genny backup that kicks in in about 2-3 seconds...it's easier to plan for startup problems. I prefer minimum 10 minutes, up to 30 minutes if there's no genny.

Our next upgrade after the PDUs is network cards for the UPSs so they can be monitored remotely, and even send alerts about power or environmental problems. In the meantime, he was free to look at the load meter at any time to see if the unit is nearing full load.

Case closed for now.
 
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