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Thread: Fuse question

  1. #1
    Join Date
    Nov 2010
    Location
    kentucky
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    186

    Fuse question

    Suppose you find one blown fuse in 3 phase disconnect, repair problem that caused fuse to blow. I have always just replaced the fuse that was blown. Coworker said all three need to be replaced because remaining fuses that did not blow were strained. Never heard such a thing before, but I learn something every day. Any thoughts??

  2. #2
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,563
    That's all that I do. Change the one that is blown and go.

    I'm hard pressed to buy the "strained" fuse theory without some real science to back it up.

  3. #3
    Join Date
    Mar 2009
    Location
    Mid-Mo
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    3,595
    Agreed, change the one out. Sales tactic? I'd be more worried about the motor that possibly single phased than the other fuses....

  4. #4
    Join Date
    Jul 2011
    Location
    East coast USA
    Posts
    962
    yup i agree. The fuse is either good or not. a bad fuse may ohm ok, but wont work if its blown....otherwise i would have a pile of almost blown fuses as spares

  5. #5
    Join Date
    Oct 2003
    Location
    las vegas
    Posts
    1,505
    when i come on that situation i always turn the good fuses upside down
    because i believe the powder around the fuses may be setteling &
    causing the fuse strip to develope a hot spot.
    i was told this many years ago by an old electrician.
    if you take an old fuse & shake it sometimes you can feel or hear the
    powder or what ever it is moving around.

  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    67,903
    Unless the other fuses look weather worn, I only change the blown fuse.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  7. #7
    Join Date
    Jun 2006
    Posts
    203
    Quote Originally Posted by marvin View Post
    when i come on that situation i always turn the good fuses upside down
    because i believe the powder around the fuses may be setteling &
    causing the fuse strip to develope a hot spot.
    i was told this many years ago by an old electrician.
    if you take an old fuse & shake it sometimes you can feel or hear the
    powder or what ever it is moving around.
    Never heard of that .It sounds good, but i would think they pack them good enough to prevent that.Still like that idea.

  8. #8
    Join Date
    Oct 2008
    Location
    Ohio, USA
    Posts
    175
    We change all three for good measure, and leave the old 2 in the box as emergency spares.

  9. #9
    Join Date
    Nov 2004
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    up in the hizzy
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    1,376
    Quote Originally Posted by Dolman View Post
    We change all three for good measure, and leave the old 2 in the box as emergency spares.
    same here, I always replace all 3, got a callback once for not doing it.

  10. #10
    Join Date
    Oct 2011
    Location
    Springfield, Missouri
    Posts
    18
    I've changed the blown fuse after checking system out if everything was normal I would try my luck on the old fuses but if it happened again then I knew to completely check out the system. I have power quality recorders along with remote monitoring boxes I built myself that has 4 channels for pressure readings. 8 inputs for low voltage recording. 6 inputs for high voltage monitoring (above 50 volts AC/DC) and. 6 control channels so I can remotely interrupt the contact signals in case of a abnormal reading and 4 of them run on cellular data with two way radio telemetry control the others are two way radio control only. So I don't have to babysit a system but I can still catch the problem that is taking place. Once I know it has went a week trouble free I change out the other fuses and hope for the best lol

  11. #11
    Join Date
    Nov 2002
    Location
    NJ - WORK IN NYC AREA
    Posts
    1,445

    Smile

    Replace all three.
    "My hands are for sale"

  12. #12
    Join Date
    Jan 2010
    Posts
    6,229
    Buy stock in a fuse company then always replace all three.
    Otherwise NO

  13. #13
    Join Date
    Apr 2012
    Location
    Paper Street Soap Company
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    2,304
    I almost NEVER find just one fuse on a 3 phase disconnect bad.

    What happens to the two remaining legs in terms of AMP draw if you drop one leg ??


    Unless it's one of the legs that feed the primary on the control transformer which for some reason isn't in my case it will cause all 3 phase motors to single phase.



    So I usually just replace the TWO that are bad and leave the third good fuse alone.

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