Can a circuit board switch itself on and off?

By geno2k3 ยท 6 replies
Oct 2, 2007
  1. Today the power went out everywhere in the house except for the kitchen and we later investigated that some of the buttons on the circuit breaker outside were switched to off. We flipped them back on and so did the power.

    Can those switches automatically switch themselves on or off? Or does it require someone to do it.
  2. Tedster

    Tedster Techspot old timer..... Posts: 6,002   +15

    that's what they're designed to do. Often with power outages, surges will occur in the main lines. Circuit breakers trip to prevent fires.
  3. geno2k3

    geno2k3 TS Rookie Topic Starter Posts: 46

    But if that is true, why was there power in a few places in the house instead of the whole house having no power?
  4. mailpup

    mailpup TS Special Forces Posts: 7,182   +469

    You have different circuit breakers to control various electrical plugs and switches. It usually not one breaker for one whole room but a switch here, a plug there, a switch in another room, etc.

    It's mostly overloaded circuits that circuit breakers try to protect. They are designed to trip if they get hot enough. I think most surges happen too quickly for breakers to react to protect anything before any damage is done. Breakers are very basic, dumb devices. That's why surge protectors for your electronic gear are recommended. They are designed for that.
  5. geno2k3

    geno2k3 TS Rookie Topic Starter Posts: 46

    No offence but you kinda confused me, can you dumb it up a little more for me.

  6. mailpup

    mailpup TS Special Forces Posts: 7,182   +469

    Take for example when your circuit breaker automatically tripped open. You noticed how it shut down only certain switches and plugs in different parts of the house. All of those switches and plugs are on one circuit so when it gets overloaded from too many things that are turned on, it will tend to get hot from all the current flowing through the circuit. The purpose of the circuit breaker is to shut off the current when it gets too hot to prevent a fire. They do this automatically for safety reasons. However, you have to manually reset the breaker as you know.

    Homes usually have several circuit breakers which control different circuits that are spread throughout the house. So when one circuit breaker is tripped, the others usually are unaffected since they are on separate circuits. The thing is when a circuit breaker trips, you should check to see why and shut off some of the load on the circuit so it doesn't do it again.

    Real old houses have fuses instead of circuit breakers. When those blow, they have to be replaced just like car fuses.
  7. Tedster

    Tedster Techspot old timer..... Posts: 6,002   +15

    circuit breakers will trip when there is a surge, over-current, or disturbance in the LINE it is protecting. There are several lines that run into a standard house. In the US, generally you will be running off of 1 or 2 (3 phase lines). These in turn are channeled down. The CB will trip when 1 or more of these phases are bad. If the other phases are ok, they may or may not trip. This is not necessarily bad. You should ALWAYS have a surge protector and an UPS on your computer regardless if your house uses CBs or old fashioned fuses.
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