+ Reply to Thread
Page 1 of 3 123 LastLast
Results 1 to 10 of 27
  1. #1
    Join Date
    Jan 2008
    Posts
    27

    Default Main Circuit Breaker Voltage Reading

    I tested the voltage of the two main hot wires going into my main circuit breaker (the circuit breaker was off). The voltage read 124V on each. I then turned the circuit breaker on and re-tested the voltage. One wire tested at 0V and the other tested at 122V. Does this mean I have a bad main circuit breaker?

  2. #2
    Join Date
    Aug 2007
    Location
    The deep South
    Posts
    459

    Default Re: Main Circuit Breaker Voltage Reading

    Did you read 0 volts on the load side of the breaker ?
    If you did , " excercise " the breaker a couple of times and recheck . Make sure all connections are tight ( use extreme caution ) .

  3. #3
    Join Date
    Jan 2008
    Posts
    27

    Default Re: Main Circuit Breaker Voltage Reading

    I don't know what you mean by load side of breaker. I will go take a picture.

  4. #4
    Join Date
    Jan 2008
    Posts
    27

    Default Re: Main Circuit Breaker Voltage Reading

    Here is the picture. Do you see where it says "MAIN" it has two wires. I tested each wire. When I went back to take the picture I tested it again. The wire on the left read 60V and the wire on the right read 122V.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	mcb.jpg 
Views:	294 
Size:	24.7 KB 
ID:	844  

  5. #5
    Join Date
    Aug 2007
    Location
    The deep South
    Posts
    459

    Default Re: Main Circuit Breaker Voltage Reading

    That looks like the wires coming from the meter base . Possibly a bad connection in there or anywhere back to the transformer secondary . If everything is clean and tight in the breaker box , then it's time to backtrack . That will involve an electrician and possibly your power company. I would start with the power company . They won't charge you for checking out their connections .

    What started this investigation ?
    Last edited by djohns; 03-16-2008 at 11:01 AM.

  6. #6
    Join Date
    Jan 2008
    Posts
    27

    Default Re: Main Circuit Breaker Voltage Reading

    Thanks! Another question, should it be reading 120V on both sides? Is it possible the breaker is bad? Is it possible one side of a breaker can go bad?

  7. #7
    Join Date
    Jan 2008
    Posts
    27

    Default Re: Main Circuit Breaker Voltage Reading

    What prompted the investigation? Last night I lost power to certain parts of my house and outlets. Occasionally the power would come back on and then go off again. None of the breakers were tripped.

  8. #8
    Join Date
    Aug 2007
    Location
    The deep South
    Posts
    459

    Default Re: Main Circuit Breaker Voltage Reading

    Yes , one side of a 2 pole breaker can fail . Are you losing the voltage on the LOAD side of the breaker or on the incoming wires ? Big difference .

  9. #9
    Join Date
    Jan 2008
    Posts
    27

    Default Re: Main Circuit Breaker Voltage Reading

    I believe its what you call the load side. Here's a better description.

    Ok guys, here is a picture of what I am working with. I think I know what's wrong. I am only touching the breaker that says "main" in the photo. Do you see those two screws on the breaker that says "main"? That's where I am taking my voltage measurements using a multimeter.



    Scenario 1: "main" breaker is set to "off" position. I put one multimeter lead on a ground and the other on the left side screw of the "main" breaker. Multimeter reads 120V. Next I put one multimeter lead on a ground and the other on the right side screw of the "main" breaker. Multimeter reads 120V.



    Scenario 2: "main" breaker is set to "on" position. I put one multimeter lead on a ground and the other on the left side screw of the "main" breaker. Multimeter reads 4V. Next I put one multimeter lead on a ground and the other on the right side screw of the "main" breaker. Multimeter reads 120V.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	mcb2.jpg 
Views:	161 
Size:	22.6 KB 
ID:	845  

  10. #10
    Join Date
    Aug 2007
    Location
    The deep South
    Posts
    459

    Default Re: Main Circuit Breaker Voltage Reading

    Check your PM box .

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •