Today on an inspection, I came across something that I find in about 10% of my inspections, an oversized breaker. That is when the breaker amperage rating is too large for the wire/conductor gauge rating that is connected to it.
In this case, the breaker was a 20 amp breaker with 14 gauge wire. Typically, a 15 amp breaker would be used with 14 gauge wire and a 20 amp breaker would use 12 gauge wire.
Why is this an issue?
14 gauge wire is designed to carry a certain current. If that current gets too high, the 15 amp breaker detects too much current and it trips, thus protecting the wire from overheating. If a 20 amp breaker is used instead, the breaker is rated for a higher current, so it doesn’t trip until potentially that wire overheats and starts a fire in the house or causes damage to the home’s electrical system.
Here are the proper wire/conductor gauges (copper, not aluminum) for the more common breaker sizes:
- 14 AWG for 15 Amp Breakers
- 12 AWG for 20 Amp Breakers
- 10 AWG for 30 Amp Breakers
- 8 AWG for 40 Amp Breakers
- 6 AWG for 50 Amp Breakers
If aluminum wiring is used, then one sized larger gauge wire should be used.
In this case, a licensed electrician should be called to investigate and make repairs if deemed necessary by the electrician.
This information is for informational purposes only. It is NEVER recommended for a home owner to remove the dead front cover from the electrical service panel. Removing the dead front cover can lead to serious injury or death (hence the name dead front cover, if you remove the front cover you’re dead). Always hire a licensed electrician for work or investigations inside the electrical panel.