Main Breaker too Big in an Electrical Panel

A main breaker is too big in an electrical panel if the wires serving it are not rated to carry the amount of amps that the main breaker is rated for. So if I have a 200 amp main breaker, and wires feeding it that are rated for only 100 amps, the main breaker is too big. Or you could turn it around and claim that the wires are too small.

A main breaker is also too big if the panel is rated for a breaker up to a certain value and the value of breaker is above the limit set by the panel manufacture. This situation is quite rare because usually the panel is bought with the main breaker preinstalled.

Main Breaker too Big in Electrical Panel

Where I Have Seen a Main Breaker too Big

I have seen both situations noted above.

The one time I have seen a main breaker that is too big for the wire size feeding it, was in Longmont, Colorado. Someone had changed out the original electrical panel that likely had a 100 amp main breaker. They replaced the panel with one that had a 200 amp main breaker. Problem is, they did not replace the wire from the meter to the panel that is rated to carry only 100 amps.

Most of the time it is a fairly easy fix to install larger wires from the meter to the main panel. But in Longmont the meters are on the street, and this panel was inside the house. To replace the wires that feed this panel would have cost thousands of dollars because the wires ran underground for 75 feet or so, instead of through a conduit that is 5 to 10 feet long.

The time I saw a main breaker too big for the panel it was installed in was years ago, and like I said, this is very rare. To check for this you can look at the documentation that is usually inside the panel. It will state the maximum size of the main breaker for that panel.

Leave a Comment

Your email address will not be published. Required fields are marked *