Went to an inspection (residential) Friday afternoon and went to the exterior main service panel. Before I got there, I heard a buzzing sound familiar to what you would hear a heat pump emit when the fan is not spinning, and the unit is on. After a small bit of investigation as to where the noise was coming from, I determined it was coming from the electrical panel. After making sure I was not going to get a shocking surprise, I opened the cover plate (not to be confused with the dead front or face plate) and was staring at a 225 AMP circuit breaker. In my experience around here, every home I have inspected, either has 200 AMP service, with associate circuit breakers or 2, 200 amp service with associated circuit breakers. I’ve never seen a 225 AMP c/b before serving a home. Has anyone else?

Sort of an odd duck for a home, but they certainly make them. A 225 amp breaker would be more commonly seen in a 3-pole version for a smaller 3phase service.

I think that would explain the noise.:wink:


     It was humming so bad at the time, I wouldn't let my client get close, much less remove the face plate. I think it was a home owner "special" install. It only got worse as I further inspected. One of those forclosure deals. I was just wondering if anyone else had run accross the same thing. I thought it was very odd at the time and I suggested that a licensed electrician further evaluate the main electrical panel.


   The noise was really bad and loud. You could still hear the humming from inside with the A/C running. It was near the panel.

Just to be clear, that humming you heard was unrelated to the fact that this was a 225 amp breaker. I didn’t want anyone to confuse that matter.

The humming could be from one of several causes, the main one’s being interior failures of the breaker due to age or water infiltration, and failures of breaker to bus connections.

Recent main panel/knife switch…225A/240V. This was in a large (3800+/- sq.ft) home built in the early 60’s. Lots of low voltage switches running the lighting system.

Scott Coslett


Is that a wooden handle, painted grey? Neat! :smiley:

You were probably right to stay out of the panel. It may have been arcing from a loose or bad connection which could only get worse with tampering.

The house in question was about 1700 square feet. Really no need for all that power. Have no clue as to why.

More likely cast iron.