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APC hums (buzzes) when hair dryer is run in another room

Discussion in 'Electronic Repair' started by BE, Nov 22, 2006.

  1. Hi!
    It's probably nothing to worry about. I had a PS/2 Model 80 whose power
    supply made a noticeable buzzing noise every time the power floor cleaner
    attachment was used on a household vacuum.

    What you are probably hearing is the vibration of a transformer. I don't
    know specifically about the Back-UPS Pro models, but the Smart UPS and Back
    UPS RS models have voltage correction circuits built into them. These can
    adjust high or low line voltage without going to battery. Your unit could be
    doing this. If it is, you won't hear any beeping. The only sign of it is an
    entry in the PowerChute software--if you are using that and have a version
    that keeps an event log. (PowerChute Plus and the APC network management
    cards (only for the Smart-UPS) do have an event log. I don't know about
    PowerChute Personal or Business editions.)

    I don't think you'll find that any damage is happening to the UPS or your
    computer. However, you really should try to ground the UPS somehow. For its
    internal surge protection to be effective, you may have to do so.

  2. <snippety-two>

    You really, REALLY need to run new wiring if you expect to be able
    to safely run modern equipment. If I were in your situation, I wouldn't
    run anything more modern than a desk lamp until I'd brought everything
    up to current code.

    No UPS was ever designed to run ungrounded. I won't be at all
    surprised if the APC's 'Site Wiring Fault' warning light is on
    continuously. At the very least, you need to run a proper ground for the
    thing, and that will also have the effect of properly grounding
    everything you attach to it.

    With an eventual upgrade in mind: Many states allow homeowners to
    do their own electrical work IF it is inspected after said work is done.
    Honestly, it's not that hard. I replaced our entire breaker panel
    (upgraded from 125-amp main to 200), and it passed inspection on the
    first try.

    Your biggest issues are to use approved wire (non-metallic sheath
    cable, recommend #12 all around so you can do 20-amp outlets by
    default), and to make sure whatever breaker panel replaces the fuse box
    has enough spots for everything you want to do.

    Do yourself a favor: Ground that APC now, and make upgrading the
    house wiring a major priority.

    Happy tweaking.
  3. Meat Plow

    Meat Plow Guest

    It didn't and that was 15 years ago.
  4. BE

    BE Guest

    Like I said earlier, it is not possible. I am a renter in this house; the
    house is located in a very desirable location of my city (among the best
    schools in the nation) and its unimproved condition allows us to pay very
    low rent. The landlord is sitting on a huge windfall if he sells because
    he's owned this property since 1969 and we don't want to push him to sell by
    making such a request (not that it would). We hope to stay at least 2 more
    years in this house. In the sense that it might make it harder to sell, the
    recent real estate downturn (and glut of unsold properties) is a good thing
    for us (but at the same time not good because my wife is a realtor).

    Hence, an upgrade to the wiring is _impossible_.
    Yes, that light is continuously on.

    I will search Google for instructions of how to prepare a ground.
    I think after using my equipment this way for nearly 10 years I can make the
    assumption that if something bad was going to happen it would have by now.

    The unit does keep our equipment running when the power goes out or dips -
    it has never failed (except when the UPS's batteries need to be replaced).
    Thanks for your considerate advice!

  5. It is rare indeed that no ground beats a good solid one.
  6. DON'T ground to a gas pipe! Your library will have a code book - well worth
    reading on grounding.
  7. CJT

    CJT Guest

    While true, I'm not sure that "good solid" applies to the ground system
    described (i.e. rods driven into the earth on opposite ends of a house,
    each grounding a portion of the outlets in said house).
  8. Meat Plow

    Meat Plow Guest

    I don't recall saying that and if I did, I didn't mean it. I only did it
    to one circuit where my elctronics are located.
  9. A ground rod is often a good ground unless the soil is very poor and dry.
  10. Sorry but you are incorrect. I have used various APC UPS models from a
    smart-ups 300 to a 1500, an old APC power cell model, and also APC Back-UPS
    1200 and a Back-ups pro 500 without a ground. All of these models will
    function without a ground.
  11. Guest

    Guest Guest

    mine has light that indicates "Grounded". when it is initially plugged in
    and the light is out, the thing doesnt run.

    even with full battery charge.
  12. huh.. what model do you have?
  13. Oh and by the way on all of mine the wiring fault light lights up when
    ungrounded, but they still function. Maybe your model is newer than all of
    mine and they have changed how they work.

    Thats intresting that they changed that, but it also makes good sense.

    - Mike
  14. jakdedert

    jakdedert Guest

    I think he said the ground light comes on while the unit is POSTing,
    then goes out. During that period of time, there is no output.

    He didn't say it wouldn't operate without a ground, and doesn't indicate
    that he's ever tried it that way. He's attributing the ground light
    issue with an actual *grounding* issue.

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