Is this corrosion in my electrical panel, and is it a safety issue?

Question

Taking the cover off my electrical panel, I notice white flakes primarily on the hot bus bar just after the main breaker and under some of the individual breakers. The breakers I have removed for replacement show no problems on their conductors (they are being replaced because of circuits being replaced, I figure why not spend a few extra bucks on renewed critical safety equipment).

Are these white flakes corrosion? A home inspector did not report any sign of corrosion or moisture in the service panel, but this is subtle. That said, these white flakes are visible on the hot bus bar under the main breaker, as in this photo:

Here are two more photos showing these white deposits under a breaker that was removed:

One other breaker was removed and had less but still some of these white deposits on the hot bus bar.

Is this corrosion, indicative of a moisture issue? Is this a safety hazard, or just something to prevent from getting worse? In case it is relevant - outside the house on the other side of the service panel, the electric meter box does show signs of rust and we need the utility company to come take a look at that.

For context, this is in a temperate climate far from coasts, on a house that is about 60 years old and otherwise seems well constructed and maintained. The house is basically all electric, with baseboard heaters and an air-sourced heat pump, electric stove/oven, electric water heater, and electric well pump.

Answer 1

That looks like good old aluminum oxide.

Is aluminum oxide a problem? It can be but this looks like it is on uncoated edges, you can stop it from getting worse with a deox or noalox (oxide inhibitors).

A plastic artist brush can be used to first knock the loose stuff off then spread some noalox on the aluminum. I do this on connection points, many are nickel coated aluminum but the coating gets scratched during assembly.

As far as some rust on the box this is also not a big deal but if external I might touch it up. Rain and humidity cause both problems and it is somewhat common on external and basement panels.

Is using noalox safe to put on breaker electrical connections, yes. It’s not only safe but most manufacturers put their custom blend on the plug in part of the breaker and it is recommended for all aluminum parts.

Part of the problem may be the alien breakers made for a copper buss may not have had the oxide inhibitors and that is the root of the problem as dissimilar metals and electrical currents without an oxide inhibitor cause damage to the least noble metal, in this case the buss bar, so hopefully they are not two badly damaged

That bussbar needs a good cleaning and a thin coat of a oxide inhibitor.

It would be best to clean and protect with the main turned off, the oxide is not conductive but you are and it looks like some work is needed to clean up from the alien breakers.

This is not the power company’s problem but yours. It might be a good idea to have a pro inspect to see if the damage warrants a replacement for safety.

Answer 2

That’s not corrosion it’s a sealant applies in the factory to Semens breakers. It to prevent from tampering with that screw and is sometimes over sprayed. Not corrosion this isn’t a battery.

Answer 3

The bus bar visible in the empty slot appears to have a lot of white on it, and the tab where the breaker isn't shows a lot of corrosion. its not a good thing when aluminum bus bars and tabs look that way. there will be breakers overheating and burning up. the traces of corrosion the op was asking about weren't actually significant, but the box needs to be replaced and the 40-45 year old breakers should be retired with it even though the ITT breakers are the ones now sold under the Siemens label.

At one time the box's guts were replaceable and you could swap to copper busses, but that hasn't been available for 20 years because of the switch to horizontal main breakers and the steel box doesn't have a lot of corrosion free years left even if it isn't rusty yet, so there wasn't any chance of avoiding the extra time to migrate all the wires anyway.