Efflorescence on an electrical breaker?

Came across this white powder located in the electrical box on only one breaker. This was located in the middle of the basement not anywhere near moisture. Any idea on what this could be???

Looks like dust to me is there a gap between the breakers for dust to get in .


It’s likely a breakdown of the sealant used on the CB screw by the manufacturer. Here’s some photo’s of two breakers, the first shows two different types of sealant, the latter photo is where I scraped off the sealant:



It looks like the sealant in your picture Robert only there is a bit more and it is now white dust. Thanks for the info guys!

looks like drywall dust or knockdown

Siemens uses a similar sealant on their breakers that resembles the one in the OP. To me it seems unlikely that efflorescence or dust would only land in that one location when surrounded by the other breakers that are clean. I would guess that the CB in question had a breakdown in the sealant.


Here is another photo of the Siemens breaker. I agree with what you are saying Robert thanks.

May be normal

I dug that white stuff out of one years ago and below it is a little screw.

It looks like the product of corrosion you get when you leave the batteries in something too long.

Yes, it did look like that Kenton but I wasn’t sure what would have created this issue. However reading some other articles on these Siemens breakers it is common.

What’s the common cause?

This is a sealant to prevent tampering or adjustment to the trip mechanism.