This is just a theoretical question to satisfy my curiosity.
A panel can be back-fed through a regular breaker. How is a main
breaker, then, different from a regular breaker? Or is it just a breaker
that doesn't give you an option of not having it?
In a typical house electric panel, electrically, a main breaker is the same
as a regular breaker. That is if too much amperage is being used, it will
trip and shut off the electricity.
Mechanically, a main breaker is pretty much designed to be a part of the
panel itself. Not designed to be easily switched out with a different value
breaker. Whereas with the other breakers in the panel, these along with
their slots are designed to easily install different types and amperages of
breakers as needed for particular circuits.
"Aaron Fude" wrote in message
"Main breaker" is defining it's usage, not necessarily how it's built. The
same thing with a breaker used as a service disconnect. The breaker is not
necessarily different from a similar type breaker used in the same panel,
however when used as a service disconnect, it requires a hold down method
Yeah, that's how the catalog is printed... :)
In reality doesn't seem there should be as much differential as there
typically is other than that a 100 or 200A main is probably somewhat
more expensive to manufacture than the typical 50/60A I've seen in the
(Maybe its my age and that we don't have any of the BORGs locally so
don't know what they're carrying but I haven't seen a full-blown 200A
panel w/o a traditional main--maybe they've started for the cheap/mass
market and I've just not paid attention, though, granted).
I would think that the main breaker would have a higher interrupt
current rating than a branch circuit breaker, just in case things go
really pear-shaped. (that is, if there's a *serious* issue, the main
breaker will provide protection in cases of overvoltages/dead shorts
that would just arc over an open branch circuit breaker.)
Now whether it works like that in practice, I don't know (IANAE)
Another difference between the main and regular breakers is that on the
main, the power is fed from the source to the terminal lugs, then to the
busbar. A regular breaker gets the power in from the busbar and out
through the terminal(s). Can breakers handle power feeds in either
Yes, I've seen it. One house I worked on the panel, they had
a double 100 breaker feeding power in, and then the various
breakers going out.
The house had problems with lights dimming, now and again.
The HO and I switched the double 100 off, and pulled that
breaker. Sanded the buss bar where the breaker fit on. Some
anti oxidant on the buss, and into the end of the breaker.
Put it all back together, and everything was fine.
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