Two receivers fried after being plugged into the same outlet

Discussion in 'Solid State' started by Roboturner91, Jun 12, 2018 at 11:59 AM.

  1. N8Nagel

    N8Nagel AK Subscriber Subscriber

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    Hair dryer on high heat is usually around 1300W. They're generally sized to be as powerful as possible without tripping a 15A breaker plus a little safety margin.
     
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  2. satellite

    satellite AK Subscriber Subscriber

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    Wow! I had no idea. I underestimated the hair-dryer. That voltage drop on the circuit seems normal then!
     
  3. toxcrusadr

    toxcrusadr AK Subscriber Subscriber

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    At 1200-1300W is what, about 10 amps at 120V? Vacuum cleaners, oddly enough, are often rated in 'amps' for marketing purposes, which always seemed odd to me, but in any case they are often in the range of 10A so about the same current draw as the average hair dryer.
     
  4. satellite

    satellite AK Subscriber Subscriber

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    Yup, 1300 watts @ 120V gives 10.83 amps.
    my vacuum is rated 12amps, so about the same.
    The vacuum is rated in amps because it's a motor load.
     
  5. toxcrusadr

    toxcrusadr AK Subscriber Subscriber

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    Yeah it just doesn't tell you very much about the performance of the vacuum, was my point. It's like advertising a car by just saying it uses gallons of gas.
     
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  6. mhardy6647

    mhardy6647 AK Subscriber Subscriber

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    There's this thing called power factor...
     
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  7. petehall347

    petehall347 the brandy coffee man Subscriber

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    voltage drop is caused by the wires carrying the supply .. plus of course the demand on the supply . i would lose 10 volts or more with a load like a vacuum cleaner .. i wouldn't expect much drop at all in a building . unless of course of long runs of cables without a proper ring main .
     
  8. N8Nagel

    N8Nagel AK Subscriber Subscriber

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    We don't do ring mains here in the US. All branch circuits.
     
  9. Roboturner91

    Roboturner91 AK Subscriber Subscriber

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    Yeah, I had attached it with the screw.

    hate to think that I blew up two receivers because of a stupid $2 grounding adapter. Expensive lesson learned, I won't mess with those any more. I had every intention of changing the outlet but a spare half-hour is hard to come by these days.

    I'm replacing the speaker wire and rebuilding the crossovers to be absolutely certain, but I was going to do that soon anyway.
     
  10. N8Nagel

    N8Nagel AK Subscriber Subscriber

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    So the box is grounded and you have an old 1-15R receptacle? Just on age alone those should be replaced, because my memory says that it was only a brief period in the 50s where grounded boxes were required but not the grounding receptacles. I mentioned in another thread that I would really prefer to use "spec grade" receptacles wherever possible when replacing.

    Probably not relevant to your receiver issues but have you confirmed that the box is in fact grounded, either through a grounding conductor in Romex or through the shield of BX/armored cable? If not, you've either got more work to do or else you shouldn't use a grounding receptacle unless the circuit is GFCI protected.
     
  11. petehall347

    petehall347 the brandy coffee man Subscriber

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    probably because of lower voltage . but then again cables need to be twice as thick even with ring main . i make that 4 times as thick for same performance on branches . or is that branches off a ring ? like what we call spurs ?
     

     

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  12. Roboturner91

    Roboturner91 AK Subscriber Subscriber

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    Box is fed by a ribbed metal conduit that I assume is BX. I have a GFCI on the other outlet in the room now that is on the same circuit.
     
    Last edited: Jun 13, 2018 at 8:24 PM
  13. N8Nagel

    N8Nagel AK Subscriber Subscriber

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    Nope, just one run from the breaker box. We use 14AWG for 15A, 12AWG for 20A (roughly 2 and 3.3 mm^2 respectively) So it's all "spurs" here.

    Not sure how you do it there but typical residential branch circuit is nominal 120VAC but that's all on one conductor, the other is a "neutral" (at ground potential, but insulated and separate from the actual safety ground) typical residential service entrance and breaker box is two 120VAC legs 180 degrees out from each other so high draw devices can get 240VAC by using two breakers. As a result of this an unbalanced load on the two phases within a residence combined with a loose neutral connection at the panel, service entrance, pole, etc. can cause the voltage on one phase to go down and the other to go up hence the mention by several people to have that checked out.
     
  14. N8Nagel

    N8Nagel AK Subscriber Subscriber

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    OK that's good, please do verify that you have a solid ground there however, the bonding strap is clean and making good contact etc.

    If you use a "spec grade" recep as I mention above most of them are self grounding, so that saves you from having to drill and tap the box for a grounding screw for a ground pigtail.
     
  15. Roboturner91

    Roboturner91 AK Subscriber Subscriber

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    I think it is, but I don't trust myself enough to make that determination on my own. I will definitely ask the electrician to check that out when he comes.
     
  16. woodj

    woodj Super Member

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    Even if the outlet was changed, without change in polarity result would be the same.
    That speaks to the error of arbitrarily adding a ground in pre existing equipment.
     

     

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  17. woodj

    woodj Super Member

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    Actually, if the extra ground had not been added to the gear, all would probably have been fine
     
  18. toxcrusadr

    toxcrusadr AK Subscriber Subscriber

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    Reading this literally made me think of this:

    [​IMG]

    Wonder how much voltage sag if this guy tried to run a vacuum cleaner. He looks like he's straining just with the light bulb.
     
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  19. Grenadeslio

    Grenadeslio Super Member

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    This guy? That's Jackie Coogan AKA uncle Fester lol.
     
  20. dr*audio

    dr*audio Fish fingers and custard!

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    Do you have a tv with cable or anything else that is grounded or plugged into a properly wired outlet connected to this system? If not, then the polarity of the outlet doesn't matter.
     

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