Are open junction boxes dangerous?
It is considered a fire hazard to have open junction boxes. Putting a cover on them can usually be done very easily. A junction box is usually a plastic or metal box that contains the electrical wire connections. The wire connections should be completely enclosed inside these boxes. If you can see the wire nuts or electrical tape, then it’s a problem. The junction box cover may have been removed or was never installed to begin with. A 50-cent cover from Home Depot is all that is usually needed.
Sometimes the boxes are crowded with wires that stick outside the box. Putting a cover onto a crowded box may not be so easy. In these cases, doing it yourself may not be an option. An experienced electrician may have to install a larger box or stack another box on top, in order to enclose all the wire connections in the junction box with a cover.
Electrical connections made improperly can be vulnerable to sparking and creating a fire. If the connected wires become loose, arcing/sparks between the wires becomes likely. If the connection is inside a junction box, the risk of a house fire is substantially low. Electrical connections outside of junction boxes that become loose and arc, can create a house fire. Most connections are in the homes attic, where insulation and other building materials can become flammable.
Finding open junction boxes and electrical connections that are not inside junction boxes, are one of the most common problems a home inspector will find. In many cases the open junction boxes have been without covers for many decades and multiple home owners without incident. They may have been left open by a do it yourself home owner or left without covers by an electrician from many years ago, before electrical codes and city inspectors became more stringent. In any case, protecting the electrical connections at your home inside a junction box with a cover, is the best bet to prevent a home fire.