What happens if I bridge L1 and L2 on a 120 genset

Discussion in 'Electrical Forum discussion & Blog' started by chefwong, Dec 1, 2012.

  1. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,255
    Location:
    Cave Creek, Arizona
    According to the Honda manual, they make a "parallel" wiring cordset to connect two EU2000i gensets together to double the capacity. But, just connecting two 120 v. generators together will NOT give you 240 power, because they will not be 180 degrees out of phase, if that is what you are trying to do.
  2. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,511
    Location:
    Houston, TX

    They work good when they are 360 degrees out of phase.

    Still a Inverter Play Toy , Good for charging a battery.

    I would not waste money using a transfer switch.

    Extension cords are cheap and safer.
  3. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

    Messages:
    1,001
    Location:
    NY State, USA
    You've obviously never used one of these things.
  4. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,511
    Location:
    Houston, TX
    I have used one and it worked very good for what it was designed for. Not that exact model but it is a Inverter.

    I have worked on the cheap overrated ones because people expect to much, and they don't run right, or make the Advertized power, and end up frying electronics.

    Wiring something like this into your House on a main change over is the part that don't make sense.

    For no longer than it will be used a extension cord would be fine.
    It is made to use as a household outlet, Not a complete Home.

    Enjoy it while it is working. And hope you do not loose things that you forgot were plugged into some outlet in the house.

    Follow the smell and smoke and keep spare parts , and keep a smoke detector in hearing range.

    A breaker or fuse will not protect everything, It is all about timing.
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,319
    Location:
    New England
    For those uninformed, something 360-degrees out of phase is misleading, as that really means that they are perfectly IN phase. Now, any phase error other than a multiple of 360 has problems, with something 180-degrees out of phase (with the same waveform) would cancel the voltage and maximize the current and fry things quickly if connected together. It is a finely balanced dance to join multiple generators together and have everything work efficiently and without smoke.
  6. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,565
    Location:
    North Carolina
    With a three phase Delta or Wye transformer the three phases will be 120 degrees away from each other.

    In a single phase 240 volt system there is nothing that is out of phase. There will be one 240 volt phase not two 120 volt phases. Each leg of the 240 volt winding will be referenced to the middle for 120 volts.

    When we connect a scope to this midpoint ground of our panels we are doing the same thing as standing in the grass between four lanes of traffic. For the sake of this discussion let’s say that two lanes are going north and two lanes are going south. When we stand in the middle and look at the south bound lanes the traffic is coming from the right and leaving to the left. Now turn around and look at the north bound lanes. The traffic is coming from the right and leaving to the left. Just as the scope we are looking at each lane of traffic directly. The sine wave will be coming from one end and leaving the other end.

    The current through that 240 volt transformer will be no different than a two D cell flash light. While one end of that winding is on the negative sine wave the other end of the winding will be positive and should we tap the middle just as with the flash light we will have two winds of 120 volts each with the same polarity as the batteries.

    The laws of physics will not let the 240 volt winding have two different sine waves at the same time. Our home is nothing more than one 240 volt winding that has a center tap. Should we connect two 120 volt systems to our homes that were 180 degrees out of phase we would have the 4 of July going on for a couple of seconds.

Share This Page