I have frequently come across breakers that will buzz or hum when a load is applied.

Most frequently,it's associated with an air handler ckt. for heat pumps.The auxillary heat or heat strips as we call them here,may not do this. It's usually when the heat pump/air handler starts.

I've seen it in different makes of loadcenters,different size ckts,have tried moving breakers around with not much improvement.

Now these are almost always ckts. in which the terminations are tight,wire sized properly,everything seems to be done correctly,but sometimes there's a slight buzz no matter what is done.

It seems to drive homeowners nuts,something isn't done right,"you're going to burn my house down" etc.

Any thoughts as to how to avoid/stop this?
Am I doing something wrong?

Russell

Earplugs!

(just couldn't resist...)

Seriously, have you tried installing a new breaker? Maybe the bus clips are a little sloppy, and the surge of power is causing a little rattling.

Cliff

An ‘online’ AC millivolt-drop test can be applied to circuit-breaker poles in panelboards, with appropriate caution.
http://ecmweb.com/ar/electric_testing_contact_quality/index.htm

Amp man, I've tried that and other remedies with varying degrees of sucess.

I,ve had this happen in different types of panels. Some I installed and some I didn't.

What puzzles me is everything seems to be in order.

Russell

Thanks Bjarney.

Found this information on "humming" in electrical equipment at the Square D website.


"...Square D has investigated several instances of reported excessive noise/humming. In most of these instances, loose hardware, wiring, and current transformers have been found to be the cause. In the few instances that this was not the case, the circuit breakers were evaluated and found to have acceptable performance and service life.

No evidence has been found to indicate that operational noise/humming is detrimental to the performance or service life of the circuit breaker..."
http://www.squared.com/us/products/circuitb.nsf/DocumentsByCategory/24B5D9B04636541885256D030061C8A6

JBD,thanks for the link. I run across this problem frequently,and usually find nothing wrong.

Customers always expect a "fix" and look at you strangely when you can't offer an explanation for it.

Russell