I was walking through a house during the middle of construction and came across what appears to be a recpticle attached to a pvc pipe that seems to pass a low voltage wire. Also connected to the receptacle was a 14 gauge wire. enter image description here

2 Answers 2


That appears to be a central vacuum system. The LV wire is to turn the vacuum on via a relay. Hard to tell from the picture if the end of the wire has simply been tucked into the pipe awaiting the final cover-plate install that it will be pulled out and wired to (correct) or if some genius ran the wire inside the vacuum tubing (incorrect.) I would bet on the correct case, though.

The 14 gauge wire would provide AC power for a beater-brush or similar accessory on the vacuum-hose.

  • 1
    Exactly. I've installed a number of such systems and Ecnerwal has it spot on.
    – isherwood
    Mar 6, 2017 at 16:20
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    I am not familiar with the specific system but I suspect the wire is to signal that the vacuum has been inserted. The beater brush is run from regular wall plug nearby. (This is the way my parent's system worked back in the day.)
    – Ukko
    Mar 6, 2017 at 21:01
  • 1
    In this case, the beater brush is actually powered by the 14 gauge wires in the top. The central power-on sense wires are the thin data-looking wire in the bottom. Mar 7, 2017 at 17:17

This question already has a very good answer but I wanted to provide a couple of pictures that will provide some additional clarity to the installation and usage.

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