The NEC (National Electric Code) does allow an electric panel to be mounted horizontally, but only if vertical mounting is not possible due to space limitations or otherwise impractical (NEC 240.33). Unfortunately, a second code requirement is that when circuit breakers are mounted in a vertical position (they are sitting horizontally in a vertical panel) the “on” position of the breaker switch has to be “up” (NEC 240.81). 

    A sideways mounted panel, like the one in the photo above, cannot have any breakers in the upper row—where “on” would have to be “down.” Also, some manufacturers specify that their panel should only be mounted vertically, so you need to check the fine print on the manufacturer’s data plate before attempting to install a panel horizontally. 

    Also see our articles What is the maximum allowed height of a circuit breaker (OCPD) above the floor? and Can I mount an electric panel upside down? and Can I mount an electrical panel face down? and Can I mount an electrical panel face up?

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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?  

• 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?

   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.