dc volt affecting ac outlet

I've blown 2 ac outlets and couldn't figure out why. The outlet just upstream of it was fine but this one outlet at then end of the line has blown twice. Both times since I changed a wire from the charge controller to the batteries. I think though that I figured out why they blew (fried, went capput, stopped working). I thought at first it must be a mouse chewing threw the wire, but then I looked at the wiring and noticed my CC to Battery wire was wrapped around the ac line. So, my thought is that a DC field was setup around the AC wire and somehow caused the outlet to blow. My question is, does this sound like a plausible explanation or not. Am I on the right track or am I just dreaming that such a field could be generated enough to blow the outlet? I unwrapped the wire from the AC line and will put another outlet in tomorrow and see if it blows. But before I go through yet another outlet, is this even possible? Any help would be greatly appreciated. Thanks.

Tim

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: dc volt affecting ac outlet

    What is "blowing"? GFI? Ground connection over heating?

    Wrapping the DC around the AC wiring--if it can induce circulating currents into the ground wire--It is certainly concivable that you could over heat a ground wire--or trip a GFI outlet...

    DC inverter input is not pure flat DC current. There is 120 HZ of ripple current--which could be coupled into other wiring if wound correctly (or incorrectly).

    I don't understand "...changed a wire from the charge controller to the batterieschanged a wire from the charge controller to the batteries" each time it "blew"?

    I do not see any "connection" between your AC problems and the charge controller wiring (is this a solar charge controller, or an AC battery charger, or what?).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • bobdog
    bobdog Solar Expert Posts: 192 ✭✭
    Re: dc volt affecting ac outlet

    Sorry for the confusing diatribe. What I meant to say is that there was a wire running from the charge controller (positive wire) to the circuit breaker and then to the batteries. This wire was wrapped around the AC wire that runs to the outlet at the end of the ac run. The outlet stopped working for some reason. So, I changed the outlet. Then the new outlet stopped working as well. So, I had a thought that it was the DC wire wrapped around the AC wire that was causing the outlet to not work.

    So, I unwrapped the dc wire from around the AC wire. Now it gets even better.

    After a few minutes I have now noticed that the outlet is working again. Weird. So my question is, could the DC wire being wrapped around the AC wire cause the outlet to stop working? If so, then could unwrapping the DC wire cause the outlet to start working again? Now I'm just curious because it sure seems that way.

    Tim

    edit: The CC is a Tristar Mppt 45 used in a solar system
  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: dc volt affecting ac outlet

    AC outlets (non GFI) don't "blow". You might burn the clips the plugs slide into for electrical contact if the plug is carrying heavy current and/or the plug is not making good contact inside the receptacle , but other than that, there's nothing to "blow".
    It sounds very much like an intermittent electrical connection between the last outlet in the string that always works, and the ones further downstream which sometimes work and sometimes don't. This has to be tracked down, otherwise with the intermittent receptacles under load, wherever the bad connection is could start arcing and cause a fire. As you describe it, it has nothing to do with the DC cables wrapped around anything. Start inspecting the connections at the last outlet that always works. The problem will be there, between there and the first outlet that's intermittent in the string, or at that first outlet in the string that's intermittent.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: dc volt affecting ac outlet

    As described? Not that I can think of.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • john p
    john p Solar Expert Posts: 814 ✭✭✭
    Re: dc volt affecting ac outlet

    Ithink you have somehow damaged the AC connection to the outlets . its all it can really be as its very unlikely there could be enough effect from the DC cable current effecting anything.
    But why was the 12/24 DC cable run wrapped around the 120v AC cable anyway?? that is a very dangerous thing to do .:confused: As wires rated for 12/24v etc are not rated to be used for 120v AC.. well thats the electrical laws in Australia.. its forbidden.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: dc volt affecting ac outlet

    You are not doing something "strange" like using salvaged aluminum wiring or very fine copper wiring?

    Some other suggestions... Many "cheap" outlets seem to not last very long or work well on well used plugs.

    And check your plugs--Many are actually a "U" shape that are supposed to have a gap in the middle to make the blade "thicker"... If it has been "flattened"--you can (carefully) take a knife blade and spring the blades back out again.

    -Bill "knives, stitches, and bandages" B. :blush::roll::cry:
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: dc volt affecting ac outlet
    bobdog wrote: »
    I've blown 2 ac outlets and couldn't figure out why. The outlet just upstream of it was fine but this one outlet at then end of the line has blown twice. Both times since I changed a wire from the charge controller to the batteries. I think though that I figured out why they blew (fried, went capput, stopped working). I thought at first it must be a mouse chewing threw the wire, but then I looked at the wiring and noticed my CC to Battery wire was wrapped around the ac line. So, my thought is that a DC field was setup around the AC wire and somehow caused the outlet to blow. My question is, does this sound like a plausible explanation or not.

    It's very unlikely. Look for loose connections and/or shorts.
  • Windsun
    Windsun Solar Expert Posts: 1,164 ✭✭
    Re: dc volt affecting ac outlet

    There is no such thing as a "DC field". A field results from the current changing, as in AC.

    Not sure what you mean by "blowing" an AC outlet. To actually blow one, you would need on the order of 30 to 50 amps at least for a 15 amp outlet.
  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: dc volt affecting ac outlet
    Windsun wrote: »
    There is no such thing as a "DC field". A field results from the current changing, as in AC.
    Not true, actually. When you were a kid didn't you ever wrap wire around a nail and hook it to a battery to make an electromagnet? You won't affect AC current with a DC magnetic field, but they exist.
  • bmet
    bmet Solar Expert Posts: 630 ✭✭
    Re: dc volt affecting ac outlet
    ggunn wrote: »
    Not true, actually. When you were a kid didn't you ever wrap wire around a nail and hook it to a battery to make an electromagnet? You won't affect AC current with a DC magnetic field, but they exist.

    And in fact, doesn't the EM field propagate in a direction 90 degrees to the flow of electrons? I seem to remember the military showing me a picture of a closed-fist with a 'Thumbs Up' as an illustration.
  • boB
    boB Solar Expert Posts: 1,030 ✭✭✭✭
    Re: dc volt affecting ac outlet
    bmet wrote: »
    And in fact, doesn't the EM field propagate in a direction 90 degrees to the flow of electrons? I seem to remember the military showing me a picture of a closed-fist with a 'Thumbs Up' as an illustration.

    An EM plane wave, (radio, light etc.), has its electric field is at right angles to the magnetic field. The changing AC electric and magnetic fields cause the combination to propagate.

    Check out this animation. There's quite a bit of info like this on the web. Usually as flash animations like this one...

    http://webphysics.davidson.edu/physlet_resources/bu_semester2/c22_EM.html


    DC electric fields are also valid. That's what static electricity is, how capacitors can store a DC charge, etc. There's lots of good stuff about this online and in physics classes.


    boB
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: dc volt affecting ac outlet

    Make sure you are wiring to the outlets screw terminals, not the push in holes in the backside.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
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  • SUNUP
    SUNUP Registered Users Posts: 24 ✭✭
    Re: dc volt affecting ac outlet
    Windsun wrote: »
    There is no such thing as a "DC field". A field results from the current changing, as in AC.

    Then how do you explain the field coils in a DC motor or Generator? they have series and shunt fields.

    or the field generated in an ignition coil for spark plugs?

    :confused:
  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: dc volt affecting ac outlet
    SUNUP wrote: »
    Windsun wrote: »
    There is no such thing as a "DC field". A field results from the current changing, as in AC.

    Then how do you explain the field coils in a DC motor or Generator? they have series and shunt fields.

    or the field generated in an ignition coil for spark plugs?

    :confused:

    We have already beat that one up. ;)