Hot and Ground continuity in Panasonic FV-20NLF1?

Discussion in 'Electrical Forum discussion & Blog' started by srtefaninla, Apr 2, 2021.

  1. srtefaninla

    srtefaninla New Member

    Joined:
    Apr 2, 2021
    Location:
    Los Angeles
    Hi All...
    First time poster, long time lurker. :) Hoping someone can answer this bizarreness...

    I installed an FV series inline fan. EVERYTHING WORKS... Let me repeat - everything is working.
    But - i'm getting continuity between the Hot and the Ground at the switch. I can disconnect the Hot and power the fan with just the Ground and Neutral or just the Hot and Neutral with ground disconnected.
    Isn't this a classic Ground Fault/short circuit that should result in a blown fuse, sparks, lots of cursing, etc.??? None of this is happening. It works. No blown fuses, all the other switches on the same circuit are fine, etc.
    I don't want to finish this up with a hot ground (which seems to be what i have here), of course - so I'm trying to figure out what the heck is going on. Why hasn't stuff blown up?
    Thanks in advance!
     
  2. fitter30

    fitter30 Well-Known Member

    Joined:
    Feb 2, 2020
    Occupation:
    Retired service tech
    Location:
    Peace valley missouri
    Are you using a ohm meter and whats its reading. Sounds like the ground and the hot shorted together blew the ground wire going back to the panel and switch side welded itself to the hot. At the switch hot and ground should be 0 volts now. When turning off breaker what other things turn off might have a problem at a receptacle.
     
    Last edited: Apr 2, 2021
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  4. srtefaninla

    srtefaninla New Member

    Joined:
    Apr 2, 2021
    Location:
    Los Angeles
    Right?! But no - none of that drama happened.

    If I disconnect all wire to switches, house, etc... - so that I just have the wire running to the fan, I get continuity between Hot and Ground, like zero resistance - the Fan itself is what is completing the circuit. I disconnected the ground from the fan body and - no continuity - infinite.
    And everything still works...
     
    Last edited: Apr 2, 2021
  5. wwhitney

    wwhitney Well-Known Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    Maybe the fan has an internal short to ground, and your circuit EGC is defective? (EGC broken, or you're missing the neutral-ground bond in your service panel).

    If you have a light socket with pigtails, or a low impedance meter you can do some simple tests. [Always turn off power when reconfiguring the circuit.] First test would be to temporarily connect the light socket from source hot to source EGC in your switch box (with the fan disconnected), and turn the breaker back on--the bulb should light. If not, you have a bad EGC (since you seem to have enough evidence that your hot conductor is intact).

    Second test would be to connect the light between the source neutral and the EGC in the cable going to the fan (temporarily disconnected from your source EGC) with the fan connected. With the fan off, the light should be off. If turning the fan on gives causes the bulb to light, you know the fan is defective with a hot-case fault. [Your resistance readings are probably already sufficient to conclude this.]

    Cheers, Wayne
     
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
    Sep 2, 2004
    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
    Most of today's digital multimeters have a very high impedance and voltage measurements can be easily misinterpreted, but resistance should be more straight forward for most. If ground is connected to the hot, you should not be able to turn the breaker back on if the end at the panel is attached - it should immediately trip. How many ohms do you measure between the hot and ground? Don't use your fingers to hold the wire to the probe tip, use a clip or some other means to make contact (i.e., keep your body out of the equation!).

    A ground fault circuit does not need a ground in the electrical connection. IT is only looking at the hot and neutral, and comparing the current on each. Everything that goes out on one lead should return on the other after going through the device. WHen they differ, it's assumed that some got shunted off to ground, which is a fault, and why it's called a ground fault...current is going to ground that should be only on the power conductors (hot and neutral).

    Some of the Panasonic fans with built-in moisture sensors are essentially 'on' all of the time, but only the sensor is being powered until it senses it should turn the motor on. If you're using one of their moisture sensing wall switches, the same applies...some part of it is always on.
     
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