The NEC or National Electrical Code has rules regarding how many wires (or conductors) can occupy a junction box. These rules ensure that conductors inside a junction box do no overheat and cause a fire. The NEC code is available for "free" after signing up here - https://www.nfpa.org/ . It is not available for download but needs to be browsed using a custom browser that does not allow copy and paste. A hard copy can be purchased from the same site or via Amazon.
It turns out that an existing junction box in my basement was too small to support any more conductors that I was planning on adding.
Fortunately these boxes can be extended by the use of an extension ring.
The addition of the extension ring would expand the internal volume and would allow me to safely add more conductors. The following table lists the volume to fill capacities, and my existing box was too small -
Precautions
Adding an extension ring is quite simple, however, it does require you to be very careful, as you may be dealing with live wires. Additionally, improper prior installations and grounding could have caused junction boxes to be energized. It's always a good idea to take the necessary precautions of turning off the electricity, wearing safety gloves and glasses, and also using a tester to ensure that the wires are not live. It's also best to leave this job to an electrician, if you are at all uncomfortable working with electricity.
Steps
- Remove the junction cover
- Add extension ring
- Tighten screws to the extension ring, so that there is no gap between the junction box and extension ring.
- Replace cover
