Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

A circuit breaker does not work properly?

  1. Jul 21, 2015 #1
    I live in Egypt where we use 220V AC / 10 A.
    When I turn light off at a circuit breaker, all lights turn off but both mains ( hot & neutral ) become hot.
    When I test them, they both have electricity (live), so I afraid to touch them.
    I would expect that they both become neutral ... Why does that happen ? and what is the solution ?
    Thanks in advance,
     
  2. jcsd
  3. Jul 21, 2015 #2

    DEvens

    User Avatar
    Education Advisor
    Gold Member

  4. Jul 21, 2015 #3
    I don’t know the exact answer, of course. However I presume in Egypt the rated system voltage is 380/220 V indeed.Most of the dwellings are single-phase supplied.

    In my opinion again, it has to be a short circuit or a large receiver in installation.

    The circuit breaker will trip for 3 times rated current in 10 seconds.

    In 10 sec. at 30 A a10 A circuit breaker could be hot.

    If the lights are off -let's take these as incandescent bulbs- it could be at least 50% drop.

    If at the end of a 100 m conductor of 1.5 mm^2 copper you'll connect a 3300 W receiver you'll get 30 A at the circuit breaker and a voltage drop of 50% [that means 110 V] for at least 10 seconds before it trips.
     
  5. Jul 21, 2015 #4
    Make sure that the circuit breaker box is properly grounded. If is is not the neutral wires can become "hot" due to feedback from other circuits.
     
  6. Jul 21, 2015 #5
    No, My house is a single-phase supplied. In Egypt, We have two mains only (hot and neutral). We don't have the third wire (ground) which is for safety.
     
  7. Jul 21, 2015 #6

    berkeman

    User Avatar

    Staff: Mentor

    You need to consult a licensed electrician to figure out your problems with your house wiring. Thread is closed.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: A circuit breaker does not work properly?
  1. Circuit Breaker (Replies: 1)

Loading...