UPS and Power Strip Interactions – What You Need to Know

electrical-powerups

Sometimes I hear that you shouldn't plug (UPS brand X / any UPS) into (power strip brand X / any power strip) because of some interaction leading to poorly conditioned power, reduced battery life, massive explosions spattering the room with battery acid, and so on. Sometimes I hear that it's the power strip that you shouldn't plug into the UPS. What I haven't gotten is a clear idea of how reliable these recommendations are or how generally/specifically they apply.

Can anyone speak precisely and non-urban-legendfully on these UPS and power strip interactions, if there are in fact ones worth thinking about?

Best Answer

Having had some 'discussions' with the inspector that comes around our offices once a year to make sure we're not being bad, I have a better idea as to what code says about this. Paraphrased from said inspector:

  • Thou shalt not plug a power-strip into another power-strip Nor any multi-outlet device into another multi-outlet device, for it is a fire-hazard, and therefore bad.
  • Thy UPS counts as a multi-outlet device Therefore thou shalt not plug thy UPS into thy power strip, nor plug thy power-strip into thy UPS, for it is a fire-hazard, and therefore bad.
  • A multi-outlet device shall only be permitted to be attached to another multi-outlet device if it is hard-wired into the first multi-outlet device Which renders it a single multi-outlet device.

The inspector wasn't kind enough to elucidate what, exactly, constitutes the 'fire-hazard'. We get dinged on the power-strip in power-strip commandment every other year or so. This necessitated the purchase of a bunch of long-tail power-strips (power strips on a 15' cord), and a few long extension cords with 3 outlets on the ends of them.

Edit: Regarding rackmount UPS's and PDU's. I believe they're OK so long as the PDU plugs into a locking outlet of some kind, such as an L5-20 or L5-30.

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