A main service panel can have up to six main breakers, per National Electrical Code [230.72(A)]. Almost all modern panels have a single main breaker, which is called a “service disconnect” in the electrical code, but more are allowed. So the panel shown above and below, which is the main service panel for an older mobile home, is code compliant because it requires exactly the maximum allowed of six switch-throws to shut off all power to the home.

    However it does not meet other code requirements:

1) Circuits are not labeled as required.
2) Because all six breakers are main breakers, they must be marked as such on dead front.
3) Several circuit wires are undersized for the rating of their breaker.

    Also, two 240V-breakers are being used for 120V circuits, and there are different brands of breakers in the panel. Both these things are allowed, but not recommended. Some manufacturer's breakers are rated for installation in another panel brand, but panel manufacturers do not honor warranties when other manufactuer’s breakers are installed. And there is one slot open for an additional breaker in the panel, but it cannot be used because installation would make the panel exceed the six-main breaker rule.

    There was an era in the mid-20th century when panels with multiple main breakers were common. See our blog post What is a split bus electric panel? for more on this.

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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?

• When should a corroded or damaged electric panel cabinet or disconnect box be replaced? 

• 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?  

• 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.