In an old house of mine (that my brother now owns) I installed a new 100 amp service about 11 years ago, which was inspected. This was my first service install so take it easy on me, it's not pretty
So about 5 years go by without any problems then main breaker failed (lights began dimming, main breaker buzzing). During replacement we noted rust stains and corrosion on breaker and bus bar. We cleaned up buss (I know your suppose to replace buss at signs of corrosion) and changed breaker.
About 3 years later the branch breakers started failing and we noted lots of rust at bottom of panel and severe corrosion on bus bar. The corrosion is so bad on bus that we are unable to remove at least 1 breaker as it is seized onto bus.
The service entry cable comes into basement about 2 feet above ground level on outside and is duct sealed thoroughly at entrance hole. Once it enters basement, it immediately raises 6" higher and proceeds to the right and down into panel. This gives it a drip loop.
Panel is mounted on a piece of plywood hanging about 1-2" off of foundation wall.
We have never seen any kind of moisture in or panel entire time.
HVAC duct is about 2 feet away.
Basement floor is dirt.
At this point I'm going to change out panel again, but before I do I have a few questions.
1. Any ideas on where the moisture would be coming from? Can it be from being so close to foundation wall and HVAC duct being close causing condensation build up in panel?
2. Would it be wise to add 2x4 frame behind plywood and insulation with R-13 fiberglass? Acceptable code wise?
3. Can the existing meter base SE cable, ground wire and rods be re-used as long as they meet current code requirements?