If the owners of this building want to add electrical circuits that will usually require either a sub panel and some massaging of wires in this older unit or more likely, the electrician will successfully point out that it'll be cheaper and safer and "better" to just install a new electrical panel with more circuit breaker positions and a single main shut-off. We can't see the rest of this electrical panel but from what we can see it may be fully populated. More examples of split bus electrical panels are shown and discussed at If so, and ifd that main breaker is close at hand, then the "rule of six" is is not violated by this panel. Note: It is possible that the panel in Bob's photo is fed from a separate main breaker or switch. Where six or fewer breakers must be thrown to turn off all electrical power to the building the panel meets the safety "rule of thumb" or "rule of 6" but if you are inspecting such a panel be sure that all of the breakers that must be thrown to turn off building power are labelled as "MAINS" What is the "Rule of Six" for electrical panels and sub panels? Home inspectors finding a split bus panel will often report the panel as "considered obsolete" and meriting replacement even if there is no visible damage note that given their age and design it's also likley that these panels are overcrowded - a hazard we cite below on this page. Watch out: experts generally agree that if more than six circuit breakers must be thrown to turn off electrical power to the building the installation is not safe and may not comply with local or model electrical codes. However the split-bus design, as we explain here, can lead to having too many breakers that must be switched off in an emergency. Split-bus electrical panels are not necessarily unsafe, and in fact some such panels like early Frank Adam panels used copper bus bars and components that appear to perform quite well.
Absence of a Main Breaker: May Violate the "Rule of Six" The electrical panel shown appears to have more than six breakers that must be thrown to turn off all power in the building as there are eight circuit breakers in the upper portion of this equipment. See those heavy wires bringing power from the upper half of the panel down to the lower half? Power on the upper bus supplies several circuits including the lower portion of the panel. In other words, there is not be a single "main breaker" that will turn off all electrical power.
Electrical power enters this panel at the top of the enclosure (in shadow, a heavy red and black wire).Ī "split bus" electrical panel is one in which circuit breaker connections are configured so that a group of breakers in the upper panel include one or more that provides power to an electrical bus in the lower half of the electrical panel. Sisson's photo (shown below) and our sketch (above ) illustrate split-bus designed electrical panels. Hazards of Split Bus Electrical Panels & the Rule of 6 Circuit Breakers In any case it is "Obsolete".ĪSHI National Board Of Directors 208-8289 several people have recommended that I recommend replacement because of the split-bus and because of the panel age and likely cost of getting additional breakers.Īnother said he didn't like how the Main connected to the lower buss with the soldered wire. Clearly this was an older, copper-bus Cutler Hammer split-bus electrical panel. The dead front and the Panel were Cuttler Hammer tan in color, and the deadfront was embossed Cuttler Hammer. Ths electrical panel also had a GE sticker on the front, but it was a stick on label. Sissons reported these interesting observations: The following photographs, provided for identification, were taken by Bob Sisson, a Maryland home inspector and ASHI Member. Cutler Hammer Copper Bus Electrical Panels Cutler Hammer Spit Bus Electrical Panel We also provide an ARTICLE INDEX for this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need. This website provides information about a variety of electrical hazards in buildings, with articles focused on the inspection, detection, and reporting of electrical hazards and on proper electrical repair methods for unsafe This article describes and includes photographs of a Cutler Hammer electrical panel fire that the electrician suspects was due to a faulty circuit breaker. We have no relationship with advertisers, products, or services discussed at this website.Ĭutler Hammer electrical panel field inspection photographs, including a CH panel fire field report: InspectAPedia tolerates no conflicts of interest.
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