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Inverter wiring

Discussion in 'Off Topic Threads' started by Calkidd, Jul 23, 2012.

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  1. Calkidd

    Calkidd Well-Known Member

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    I am hoping that I may find some help on here.

    I have a Harbor Freight 2000 watt inverter that I attempted to install into my RV travel trailer. I am having an issue, but let me explain how I have it wired.

    I have 4AWG cable for both positive and negative sides of the inverter that go directly to the batteries on the trailer. I took a 12AWG extension cord, cut off the female end and ran it into the trailer's control panel. After stripping the extension cord I put the white to common, green to ground, and black to the 30 amp breaker on the 120v side and plugged in the male plug into the inverter.

    When I first fired up the inverter I unpluged the 120v cord (that leads to the control panel) and turned on the inverter with just 12 volt power and nothing plugged into the 120v receptacles. The inverter powers up and runs fine however my VOM only shows 99 volts. My next step I plug in 120v cord to the inverter, but turned off the 30 amp breaker for cautionary reasons and turned on the inverter. As soon as soon as I turned on the inverter it powers up, but then the amp meter (built in) pegs to 200 amps and the alarm sounds and the inverter goes in to over load.

    Once the above is done the inverter powers on the same way with or without it being plugged in to the 120v source. Once it turns on it goes into over load.

    Does anyone have any suggestion of what I might have done wrong? By the way this happened with two of the same inverters. Was my wiring in to the control panel wrong? I have no experience with inverters.

    Bryan

    If it helps I can take photos to show wiring.
     
  2. HSLDS

    HSLDS Well-Known Member

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    You don't say what the power supply is feeding... BUT, a 30 amp breaker is designed for a load of 3600 watts, and the feed wire for same should be 10 gauge (12 gauge is rated for a 20 amp feed - 2400 watts).

    One thing to try is turning off everything that the panel feeds - then slowly add them one at a time and see what happens. Read on, in that there are some things to verify before doing this.

    So you might be overloading the draw capacity of the unit (I do note that it is rates to peak of 4,000 watts, but it is the 2,000 watt continuous you are fighting).

    The output voltage of 99V leaves me suspect as well... Are you sure you are drawing 12 volts?? (Many camper set ups use two six volt batteries to store extra amperage) I would verify 'full voltage' feeding the unit - typically this will be about 13.5 V.

    You may also be exceeding the battery's(ies') ability to provide raw amperage to supply the inverter as opposed to voltage. Have you tried it with the engine running to see if that will raise the output of the unit??

    -

    Simple formula: Watt = Amp X Volt

    For you W = 30 X120 = 3,600
     
  3. halfmile

    halfmile Well-Known Member

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    "The inverter powers up and runs fine however my VOM only shows 99 volts."

    You should have a potential of 117 VAC without a load. At this point either you don't have enough battery (as stated should be 13.5 no load) or the inverter is not doing its job. I also do not know inverters, but I don't think the 99 volts is usable.

    If you have microwave or air in your setup you need some snot to run those babies. I run a generator, and the microwave will not omake popcorn if the air is on. Mind you this is a contractor 6500 watt unit.

    Go talk to an RV specialty place and you may get some very negative reports on harbor freight electronics. I bought 2 little dremel type tools and they quit turning when you touch the work.

    The best things you can buy from HF are inert objects like hammers or trailer hitches.

    HM
     
  4. Calkidd

    Calkidd Well-Known Member

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    I think I found my issue. While looking at other inverters I found this warning.

    <i>Do not connect the Inverter to RV or household AC distribution wiring, to an AC load circuit
    or where the neutral conductor is connected to the negative terminal of a DC power source.
    Connecting to these circuits could cause damage to the Inverter and/or create a spark.</i>

    I believe once the inverter is plugged into the RV AC source it is being back fed because the RV's DC and AC utilized the same ground.
     
  5. HSLDS

    HSLDS Well-Known Member

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    You're mixing terms here.

    Do you mean the 'neutra'l or the 'ground?'

    The white wire on AC is called the neutral, the bare copper/green is the ground, the black will be the load. For the DC red will be '+' and black will be '-' (ground).

    The power distribution box, as set up for your camper SHOULD have these two legs (neutral and ground) isolated from one another (in a typical primary house pannel they can share the same screw down points - any secondary panels should also have the grounds and neutrals isolated). If not there is a risk of a 'ground fault' and power can flow the wrong way - risk of shock with that...

    SO - to answer the question, in the power panel for the RV the black wire should feed the breaker side of the circuit, the white should tie the neutral returns together, and the bare copper/green should be isolated by itself (isolated from the white neutrals) and lead to a true ground.
     
  6. E. Beaver

    E. Beaver Member

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    I have a 750 watt Harbor Tool and Freight inverter.

    The no load voltage is 95 and goes up as more of a load is applied.

    Called Harbor tech support and they confirmed that the voltage would be 95 or so.

    I purchased an Ames 1250 watt inverter and its no load voltage is 115 and holds steady when more of a load is applied.

    Charlie
     
  7. halfmile

    halfmile Well-Known Member

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    Ah, good things from the Beav.

    And the ground loop info too.

    HM
     
  8. MBT-99D

    MBT-99D TS Member

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    For you W = 30 X120 = 3,600

    This would only apply if you truly had 120 volts and knew amprage draw.

    You know your voltage is 99 lets say your amprage (load) is 20 amps

    there for you would only be loading your inverter to partial load.

    20x99=1980 watts. as opossed to having a true 120 volts it would be 20x120=2400 if your inverter has a load capability of 2000 watts running ad 4000 peak you will need to take an amperage reading on the RV load to see if this inverter is even big enough to do the job.if you read 28 amps true load on RV even at 120 volts you would have 28x120=3360true load

    Most electronic devices are designed with under/over voltage protection also. If you are only getting 99 volts out i would look at what voltage is coming in, I don't think you have a inverter issue i would be suspect of the source voltage. If your battery is old and getting weak it may show a good 13.4 volts but collapse when you engage a load such as the inveter. You will need to check your battery voltage while the inverter is on and under load.
     
  9. E. Beaver

    E. Beaver Member

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    Purchase a Kill A Watt at Home Deopt etc, for about $30.00.

    Plug it into your inverter, then plug in what you want to run into the Kill A Watt.

    The Kill A Watt will show voltage and amperage and wattage. It will even track what you use over time. It is a very useful device.

    Charlie
     
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