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-   -   3-prong generator & 4-prong power cord (https://www.askmehelpdesk.com/showthread.php?t=261271)

  • Sep 16, 2008, 07:50 PM
    vegasSteve
    3-prong generator & 4-prong power cord
    My 5kw Coleman Powermate generator has two 110v receptacles and two 220v receptacles. Both of the 220v receptacles are the 3-prong blade type. My six circuit Reliance ProTran transfer switch has the 4 prong female twist lock. Both ends of my 30amp 4-wire cord are twist lock. The end for the transfer switch is no problem. My Coleman manual states if I am going to use the 220v receptacle to power up any 110 circuits, I have to use the transfer switch. It also says I have to have an adapter plug inserted into one of the 110v receptacles. Something I didn't understand about floating and bonded grounds. It says the ground and neutral terminal on the adapter plug has to have a jumper wire connecting the two together.
    I was going to buy a three blade male plug that fits the configuration of the 220v receptacle on the generator. I thought I could cut off the male end of the 30amp power cord and hook the wires up to the new plug. My plan was to just connect the white neutral wire and the ground together on the new plug. Will this be the same thing as making an adapter plug and pluging into one of the 110v circuits? Will it work? Any other alternatives? Thanks, Steve
  • Sep 17, 2008, 07:02 AM
    KISS
    I'm only slightly confused.

    GIVENS
    With the 240 receptacles you have 2 hots and a ground.
    In order to get the neutral, you have to get it from the 120 V outlets.

    Let's assume that all the grounds of the receptacles are tied together and assume that the transfer switch does not switch the neutral.

    EDUCATION
    A system requires that ground an neutral be tied together at one place. In the home there is one place where the neutral and ground and a ground rod come together.

    Generally when a generator is used to power a house the neutral/ground bond is removed and that takes place in the house.

    CONFUSION

    As I see it. If the transfer switch is used alone then the ground and neutral need to be bonded together at the generator.

    If the transfer switch is used in combination with a household panel where there already should be a bond between ground and neutral, you need to get the neutral and ground from the 120 V receptacle and get the two hots from the 240 V receptacle.

    So, in this case the ground will be bonded to the neutral in the same place that the house bond occurs.

    It is important that this bond occurs, but occurs only once.
  • Sep 17, 2008, 11:08 AM
    vegasSteve
    Thanks, I intend to use the transfer switch wired into the main panel to power up 6 circuits in the event of a power failure. What I need to know, given the configuration as stated, is what do I need to do to the one end of the power cord to get it to work with the 240v blade type receptacle on the generator. The cord is a male twistlock 4-wire, that I thought I could cut off and wire into a new 3-prong male blade type plug. Do I still need to make up an adapter plug to stick in one of the 110v receptacles or not, if I incorporate the white and green wires together on the new plug
  • Sep 17, 2008, 01:14 PM
    KISS
    This explains things a little more than I can:

    Portable generator neutral rewiring

    I just checks on the Coleman site and nothinng there can help me.

    I'd suggest to do the neutral ground check as outlined above. No neutral ground bond.

    If it fails, then your in good shape providing the transfer switch does not switch the neutral. High probabbility.

    You will then need to make a "Y" cord that grabs the two hots from the 240 recptacle and the ground. You will then connect the neutral wire to the 120 V recepacle.

    In your best interest, I think it's best interst to mount a 4 wire twist lock on the generator.

    Then for portable operation wire a twist lock plug with ground and neutral jumpered together, so you comply with code.

    That takes care of it.
  • Jan 1, 2013, 03:45 PM
    rschlack
    I have a very similar question but my generator is 3500 watts with a 3 prong 120v 30amp female. My house has a 4 prong twist lock going into a 30 amp circuit breaker.

    Can I just take the end of my 4 prong cord off, tie the neutral and ground together and put on a 3 prong male end?
  • Jan 1, 2013, 04:19 PM
    stanfortyman
    That is not what makes it a 3-prong.
    The generator is 120V, the house inlet is 120/240V.
    You can make a cheater cord but it will only provide 120V to the house so you will have to shut off any 240V breakers.
  • Jan 1, 2013, 04:30 PM
    rschlack
    Yes, I will only use it to power a few 120v items. But I just don't want to o anything that would cause bad things to happen. Am I correct in thinking that I can tie the neutral and ground together to get just a few essential items up and running?
  • Jan 1, 2013, 04:32 PM
    stanfortyman
    But why do you think you need to do this?? The N & G are separate in both the generator and the house inlet.
  • Jan 1, 2013, 04:38 PM
    rschlack
    The cord has 4 wires, 2 hot, N and G. The generator has 3 prongs. So I just thought that 1 of the 4 wires has to go.
  • Jan 1, 2013, 04:41 PM
    stanfortyman
    Right. Your generator has ONE hot, neutral and ground.
    You need to jump out the two hots at the house end of the cord.
  • Jan 1, 2013, 04:47 PM
    rschlack
    Thanks for the advice.

    Rob
  • Jan 1, 2013, 04:48 PM
    rschlack
    Thanks for the help

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