circuit braker tripping

Discussion in 'General Electronics Chat' started by samjesse, Jul 19, 2018.

  1. samjesse

    Thread Starter Senior Member

    Sep 14, 2008
    212
    0
    Hi

    The house wall plug has 3 wires. I jumped the green "earth" and either of the red or black but did not trip the circuit breaker. Isn't that considered a short to ground and thus suppose to trip the fuse?

    The reason I did that is because few weeks ago, I mistakenly jumped the red and the black and that tripped the circuit breaker.

    Thanks
     
  2. dendad

    Well-Known Member

    Feb 20, 2016
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    It sounds like there is an open earth now.
    Is there power on that outlet?
    With a meter, measure the volts from active to neutral, and it should be the same as active to earth.
    If the circuit has earth leakage protection, a lamp from active to earth should drop the power.
    It is never a good idea to just loop the active to neutral or earth.
    The breaker may be damaged now, or some connection in the circuit.
     
  3. thedoc8

    Active Member

    Nov 28, 2012
    69
    7
    Probably the breaker was already trip.
     
  4. MrChips

    Moderator

    Oct 2, 2009
    16,887
    5,200
    There are usually three wires, LINE, NEUTRAL, EARTH.

    Connecting LINE to NEUTRAL will trip the breaker.

    Connecting EARTH to NEUTRAL will not trip the breaker but ought to trip a GFCI, ground fault circuit interrupter, if one is installed.
    Connecting EARTH to LINE ought to trip the breaker. If it doesn't then it indicates that you do not have a proper EARTH wiring.
     
  5. SLK001

    Senior Member

    Nov 29, 2011
    1,166
    426
    He's in Australia, so not likely 120V.
     
  6. samjesse

    Thread Starter Senior Member

    Sep 14, 2008
    212
    0
    I took some reading:
    97V between the black and the green
    148V between the red and the green
    246V between the red and the black
     
  7. KeepItSimpleStupid

    Distinguished Member

    Mar 4, 2014
    2,841
    497
    Sounds like you have a broken ground. The 97+148 = 245 is due to a leakage path in some device that's plugged in. You will likely find that you can draw very little current (<1 mA) from that. The fact that a short between green and black didn't trip the breaker pretty much confirms the open ground.

    Your not in the US, but if you were in the US, grounds cold be daisy chained. If they are just twisted, that connection won;t be gas tight. they need something like a wire nut or terminal to make that connection.

    So, I suspect somewhere in the daisy chain process there is a bad connection. In the US, it's required to make a thru-ground connection AND a connection to a metal box and a connection to the ground (green) terminal.

    it's not a fun problem to track down.

    You need to first identify what outlets are on the circuit and hypothetically figure out it's path.

    I'd unplug everything. Unplugging something like a computer should make that voltage go away, but it does not mean the device is broken.

    Once the stray voltages go away, you can use an ohmmeter to look at ground to neutral resistance by bisecting the path. e.g. disconnect at the middle. Do a neutral to ground resistance. If none, move closer to the panel by bi-secting that path.

    The hard part is figuring out the path.

    I had a hot to ground short in a circuit that included one or 2 ceiling fixtures and some outlets. When I disconnected wires in the ceiling fixtures, I lost power to 4 outlets. The first of the 4 had the problem. In this case, I went with the first because that was messed with about a year ago.
    When i took the outlet out of the box, but still connected, the problem went away.
     
  8. dendad

    Well-Known Member

    Feb 20, 2016
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    The same applies here in Oz, with our 240VAC..
    Generally, "Line" is referred as "Active" here.
    It will be worth while getting the wiring looked at. Here, it should be only touched by a qualified electrician.
     
  9. Tonyr1084

    Well-Known Member

    Sep 24, 2015
    2,199
    485
    As "Accidents happen" I accidentally struck hot to neutral and got virtually no spark. In fact, I didn't even notice it. Turned out there was a Arc Fault Circuit Breaker (AFCB) protecting the circuit. At that time I had never experienced such a thing. Now I know about them. Don't know why they're not standard in homes. Maybe they are. Maybe they're becoming the new standard. The bad thing about old style breakers is that it takes a ton of current rush to trip them. So if you accidentally strike hot to ground or neutral you get a hot spark that can start a fire inside a wall.

    Whatever the circuitry problems you're experiencing I'd not recommend continued testing in the manor you're employing. You COULD start a fire or zap yourself. With the level of understanding you seem to have I'd recommend hiring a professional. Something I find myself doing more and more of as I continue to successfully age. Successful because I stopped doing dumb things years ago. At least I hope I did.
     
    dendad likes this.
  10. SLK001

    Senior Member

    Nov 29, 2011
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    They are now required by code on new homes and remodels. Since 2002.
     
  11. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    5,378
    1,187
    +1...
    I'm always amazed at the dumb stuff I hear people doing here to "experiment" before they have gained proper knowledge..
    Most seem to want to run before they learn to walk..
    Its easier to kill yourself than it is to learn to be safe..

    Or lets just call it population control/weeding out the weak..
     
  12. KeepItSimpleStupid

    Distinguished Member

    Mar 4, 2014
    2,841
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    The above is really hard for a novice to fathom. Where does 97 and 148 come from. 97+148 adds up to ~246 V

    I will take you to this http://farnell.com//datasheets/1576600.pdf page #2. Note the two capacitors to ground, The model for a capacitor would have a shunt resistance, that's your leakage current. The 1st page shows a leakage current around 1 mA. That's where the numbers come from.

    If you remove that ground, usually ~1/2 the mains voltage appears. Now anywhere along that cable, ground has a potential to neutral. You can't draw much current from it. It's basically a resistive divider with two caps with the same leakage. In your case, it's asymetric.

    Another way induced voltages appear is by induction. Live wires against dead ones will induce a voltage. That's more of a "phantom voltag:.

    In all likliness, there is a three pronged device with an RFI filter in it, that is placing a voltage on an unconnected ground. The problem would be found at that outlet or closer to the main panel.
     
  13. Reloadron

    Distinguished Member

    Jan 15, 2015
    3,505
    1,567
    While I can't speak for other states the way the NEC code works is like this:
    "AFCIs and the NEC
    Since the 2008 edition, the National Electrical Code has included significantly expanded requirements for AFCI protection in all new homes. However, these new provisions do not become effective unless the current edition of the Code is formally adopted into state and local electrical codes. State adoption and enforcement of the NEC with its AFCI intact is key to preventing fires, protecting homes, and saving lives.

    Home builders in some states have challenged the increased requirements for AFCI technology, claiming that these devices will significantly increase the cost of a home while making very little difference in improving safety".

    Enter the problem. I can buy a 20 Amp circuit breaker for about $4.00 USD. The same 20 amp breaker with AFCI runs about $45 to $50 USD. Roughly ten times the cost just using the Square D Homeline versions as an example.Most new construction involves a new 200 amp service panel which houses 20 to 40 circuits. Now personally I have no issue with the added safety for the cost but apparently home builders see things differently.

    My wife is out of town visiting with her cousin in PA, they are both visiting her cousin's mom, my wife's aunt. So her cousin gets a call from her husband in the Phoenix, AZ. area. Seems they had a house fire. The smoke detector woke Barry and when he investigated he saw nothing and smelled nothing. He silenced the smoke detector (I have no clue how) and went back to bed. Smoke detector goes off again as Barry complains about the sensitivity of the thing but this time he ventures out in pouring rain and sees smoke billowing from his roof. Good thing the smoke detector was persistent as sometimes Barry is not real quick on the uptake. Insurance placed the damages at $100,000 from Fire, Smoke and Water. The problem? A can light in the kitchen apparently was arcing above the ceiling. Cousin Debby is not thrilled about going home. Maybe another month in PA with her mom?

    Me? I can't help but wonder if an AFCI would have prevented all of this? While the NEC can write code they can't make states enforce what they write. Most states simply copy the NEC but they are not under any obligation to include it in their own state codes. Before I forget the above quote was taken from here. Here in Ohio new construction of residential does not require AFCI. Not unless the Ohio code has been revised and I am just not aware of it. Maybe I should suggest AFCI to Barry? :)

    Ron
     
  14. olphart

    Active Member

    Sep 22, 2012
    76
    18
    Intermittent load arcing is exactly what AFCI will trip on.
    A buddy's house had an AFCI tripping issue. Turned out the builder used the "backstab" wire method on the outlets (BAD DOG).
    Pushing the outlet into the box released the grip force on the wire. It showed up when he'd print from his system - a laser printer.
    On going active, the circuit would arc, tripping the AFCI. I changed all outlets from backstab to screw down - issue solved.

    AFCI breakers are much more $, but outlets are about same as GFCI types. In the lighting case, it's doubtful those circuits would be AFCI, so fire would still happen. Also, seems like somebody used cans not rated to be buried in insulation. Arcing in a box is a problem, but usually not a fire. Michigan requires AFCI bedroom outlets, but not lighting or other outlet circuits.
     
  15. samjesse

    Thread Starter Senior Member

    Sep 14, 2008
    212
    0
    After fixing the earth wire, I purchased RCBE but not sure if it is polarity sensitive or not "please see image".
    Does it matter which side of the unit the load is connected to?

    Thanks
     
  16. dendad

    Well-Known Member

    Feb 20, 2016
    1,972
    514
    I think the load is the bottom, "2" side.
    The side with the switch contacts is the input so when the contacts open, the power is removed from the rest of the internal circuitry, and the load.
     
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