Corrosion at interior components of an electrical panel creates several safety problems:

1) Circuit breakers are mechanical devices and, like any mechanical device, corrosion can cause it to freeze up and not trip when too much current is flowing in the circuit. This will overheat the wires and possibly start a fire.

2) Aluminum corrodes into a crystalline white powder and, although aluminum is an excellent conductor, aluminum oxide is an insulator. An example of corrosion forming at aluminum bus bars, along with rust stains, is shown below.

    Anti-oxidant paste is required to be applied over exposed aluminum wire at connection lugs in a panel. But, if that is not done or excessive moisture attacks the aluminum, the wiring can overheat and start a fire. A demonstration is shown in the video below.

3) Although corrosion can occur inside a panel due to a humid environment, most panels with severe corrosion of the internal components have a defect that allows water to drip down through the panel box. Rust at bottom of the interior is a sure sign of water intrusion, and the water draining through the panel box can also cause an electrical short and fire. One common way that water enters a service panel is when the cap piece on the weatherhead at the top of the service mast goes missing, like in the photo at right. Water goes straight down to the top of the box in many cases.

     Eventually, corrosion will completely destroy the panel box To read more about  it, along with the ways water gets inside, see our blog post When should a corroded or damaged electric panel cabinet or disconnect box be replaced? 

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Here’s links to a collection of our other blog posts about ELECTRIC PANELS:

• What causes copper wires to turn green or black in an electric panel?  

• What is the maximum number of circuit breakers allowed in an electric panel?

• What is a tandem circuit breaker? 

• When did arc fault circuit interrupter (AFCI) breakers first become required?

• Can an electric panel be located in a closet? 

• Can an electric panel be located in a bathroom? 

• Can you add circuit breakers by different manufacturers to an electric panel if they fit?

• My circuit breaker won't reset. What's wrong?  

• What is a split bus electric panel?

• How do I identify a combination AFCI (CAFCI) circuit breaker? 

• What does a circuit breaker with a yellow or white test button indicate? 

• What is the maximum gap allowed between the front of a recessed electric panel box and the wall surface surrounding it? 

• What are the requirements for NM-cables entering an electric panel box?

• Why is a fuse box/panel an insurance problem for homebuyers? 

• Why is bundled wiring in an electric panel a defect?

• What is the difference between GFCI and AFCI circuit breakers? 

• Why are old electrical components not always "grandfathered" as acceptable by home inspectors?

• What happens when you press the "TEST" button on a circuit breaker in an electric panel?

• What is a Dual Function Circuit Interrupter (DFCI)? 

• What is the difference between a Combination Arc Fault Circuit Interrupter (CAFCI) and an Arc Fault Circuit Interrupter (AFCI) circuit breaker?  

• What is the difference between "grounded" and "grounding" electrical conductors? 

• What does it mean when a wire is "overstripped" at a circuit breaker?

• Why is an old fuse panel dangerous?  

• Who is the manufacturer of those "bad" electric panels?

• Why is the circuit breaker stuck in the middle? 

• What is a double tap at a circuit breaker?

• What is the right electric wire size for a circuit breaker in an electric panel?

• What is the life expectancy of a circuit breaker? 

• My circuit breaker won't reset. What's wrong? 

• Why do some breakers in my electric panel have a "TEST" button on them?

• What is the right size electric panel for a house? 

• What do I need to know about buying a whole house surge protector? 

• What is the maximum allowed height of a circuit breaker (OCPD) above the floor?

• What is the maximum height you can mount an electric panel above the floor? 

• What is the code required clearance in front of an electric panel?

• What is the main bonding jumper and where do it find it in an electric panel? 

   Visit our ELECTRIC PANELS page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.