A split-bus panel requires shutting off up to six breakers to disconnect all the circuits served by the panel. There is no single main breaker. Although production of split-bus panels ended in the mid-1980s, the allowance for a “maximum six switch-throws" rule stayed in the National Electrical Code until it was removed in the 2020 edition (NEC 230.71). So any new electrical installations require a single main breaker per panel to shut off all power, but an existing split-bus panel from years ago is not illegal.

    Even though allowed to remain, many split-bus panels have safety issues that make it worthwhile to consider replacement, and several manufacturer’s panels have been deemed unsafe and not insurable, such as Zinsco and Federal Pacific. See our article What are common problems with split-bus electrical panels? for details. Also go to What is a split-bus electrical panel? for an overview of how they function. 

• • • • • • • • • • • • • • • • • • • • • • • • • • • • 

Here’s links to a collection some of our other blog posts about OLD AND OBSOLETE ELECTRICAL:

• Is knob and tube wiring illegal?

• How do I find out the manufacturer of an old electrical panel? 

• Is all cloth wiring dangerous? 

• When did they stop using aluminum wiring? 

• Is tinned copper wire safe? 

• Why is there a 3-phase breaker in a single phase electric panel with only two bus bars? 

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

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

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

• Why are Zinsco and Sylvania-Zinsco electric panels a problem? 

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

• Should I buy a house with a fuse panel/box? 

• How dangerous is rust and corrosion inside an electrical panel?

• Are old fuse boxes illegal? 

 • I heard that aluminum wiring is bad. How do you check for aluminum wiring? 

• Are Wadsworth electrical panels dangerous? 

• Are two-prong outlets up to code and legal?

• How old is a Walker EQ Load Center electrical panel? Is it unsafe? 

• How old is a Pushmatic electrical panel? is it safe? 

  • What are those strange looking wall switches in houses from the 1950s and 1960s? 

 • How dangerous is old electrical wiring? 

• Why is there no bathroom electric receptacle in this old house?

   Visit our ELECTRICAL - OLD AND OBSOLETE page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.