1

Today my TP Link Kasa smart switch started acting strange (turning on and off randomly) - it is broken now. When I hit reset button, a few drops of water dropped out. I removed the plate, pulled the switch out and noticed water inside.

I am in Illinois so my electrical wiring is running inside metal conduit (EMT). When my wife turned on hair dryer I noticed some extra water dropped from the EMT into electrical box. Water is dropping directly on the switch and through the ventilation vents (in red) going inside the switch and of course burns the switch.

I went to the attic and everything is dry there, so my guess is that it is condensation and when there was power consumption heat just increased the effect of that.

It is now around 30°F outside so not yet very cold. I had switches installed more than 1 year ago and they were working without any problems last winter when it was colder.

Do yo have any thoughts? Should I add some kind of insulation to conduit in the attic?

enter image description here

FreeMan
  • 48,261
  • 26
  • 101
  • 206
Arek
  • 71
  • 2
  • 9

2 Answers2

3

Weep Holes

NEMA (as in "NEMA 5-15 receptacles", that NEMA) has some guidelines on this online. Basically they recognize that electricians drill drainage openings (weep holes) in conduit bodies and junction boxes and are officially sanctioning the practice:

  • Minimum 1/8" (I think smaller is ineffective), maximum 1/4" (bigger holes can cause other problems)
  • One per conduit body or box (exception: divided - e.g., to separate two circuits or to separate low voltage from mains - can have one hole per section)
  • Always in the bottom and not too close to an edge or corner
  • Only in boxes listed for damp or wet location - if it isn't listed for damp or wet location and it is getting wet then you have bigger problems

Insulation may help some, but keep in mind that condensation (or other water) can travel a long ways, as long as it keeps moving down. In addition to temperature, you also have to consider humidity. But some condensation may just be inevitable and in that case weep holes are the way to get rid of it.

manassehkatz-Moving 2 Codidact
  • 139,495
  • 14
  • 149
  • 386
2

Water will condense inside conduit in cold areas that have openings to heated living spaces that will have higher moisture content. In such cases, duct seal putty is in common use to seal the openings to conduit at boxes and cabinets.

kreemoweet
  • 4,598
  • 16
  • 17