Premature CB failure due to moisture?

[Sparky5150]

How much of an issue is there for a CB if it sits idle in a NEMA 3R panel exposed to the elements?

I know these breakers operate without issue all the time outdoors, but I have a client that has many panels on site that have no load on them for long stretches at a time, then when he needs them most some breakers fail when they become energized.

Is it possible that the breakers build up moisture within while idle, then once energized the moisture causes them to short out/fail?

The breakers are standard 208 volt 400 and 200 amp 3 pole.


Thanks for any experience you guys can share.

 

[Jraef]

How much of an issue is there for a CB if it sits idle in a NEMA 3R panel exposed to the elements?

I know these breakers operate without issue all the time outdoors, but I have a client that has many panels on site that have no load on them for long stretches at a time, then when he needs them most some breakers fail when they become energized.

Is it possible that the breakers build up moisture within while idle, then once energized the moisture causes them to short out/fail?

The breakers are standard 208 volt 400 and 200 amp 3 pole.


Thanks for any experience you guys can share.

The failure is most likely due to corrosion as a result of atmospheric moisture, time and heat/cool cycles from exposure. If power is being fed to them continuously, use space heaters in the box. If not, or they are concerned with power consumption of the heaters, there are chemical "corrosion inhibitors" available that can be put into the box. They are essentially a sponge impregnated with a chemical that evaporates and coats everything with a water displacer (like WD-40). They don't last forever so they would have to be periodically replaced, which tends to be forgotten over time so it's less than ideal, but better than nothing.

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