So I went to replace the batteries in my thermostat and when I pulled it off I noticed a black wire was unplugged. I'm not sure if it's suppose to be like that or if I accidentally pulled the black wire out since the screws on the backplate were loose. It's a white and black wire. The white wire is still connected to the W and the black wire is not connected. Is it alright to leave it this way until I get back from school? I'm already late trying to figure out where the damn black wire goes. Thanks

  • Two wire system wires go to R and W Feb 25, 2015 at 18:29
  • The R and Rc are jumped, do I need to power anything down before connecting the black wire? Thanks
    – Rhys
    Feb 25, 2015 at 18:34
  • No, R and RC are usually jumpered on a single heating or cooling system. BTW if you leave it unconnected then I don't think anything bad will happen except for the heating system not coming on which may be an issue if it's very cold. Feb 25, 2015 at 18:36
  • Alright I've connected the black wire to R leaving it jumpered to RC. Will I die if the wire is in the incorrect spot?
    – Rhys
    Feb 25, 2015 at 18:40
  • Nope. You'll die, eventually, regardless of where the wire is, - it's a consequence of being alive, inescapable, inevitable, and unrelated to thermostats.
    – Ecnerwal
    Feb 25, 2015 at 18:41

1 Answer 1


The only risk is if you live in a cold climate, your pipes could freeze and burst, flooding your home. This is unlikely to occur in a few hours, but keep in mind the time of day and the availability of stores and professionals should you need additional supplies or assistance. If it's -30 out, this isn't something you want to leave broken for 24hours.

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