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Wiring nema 5-15 to L14-30?

Discussion in 'Electrical Engineering' started by Wes Newell, Jun 15, 2008.

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  1. Wes Newell

    Wes Newell Guest

    My small generator only has 5-15 receptacles with common 120v output and I
    need to wire this to a L14-30 receptacle on a transfer switch to provide
    120v power to both sides of the switch so I can use all 10 circuits. I
    don't see a problem with this but I can't find anything about it after
    many hours of searching the web. So what I plan is to use 2 120v outputs
    from the generator and just double up the neutral and ground and then put
    each hot lead on the separate hot leads of the the L14-30 thus giving the
    same 120v to each side of the transfer switch. The generator is only 2300W
    max, so I'm sure there won't be a problem using 12 or 14 AWG scrap
    extension cord (SOJT 600V) for this. I'm trying to confirm I'm not missing
    something. The generators ground is not common with neutral and the
    transfer switch is a Connecticut Electric EGS107501A. I've already wired
    the switch in and it works fine from the line side. Just need to get the
    generator side hot.
     
  2. Guest

    | My small generator only has 5-15 receptacles with common 120v output and I
    | need to wire this to a L14-30 receptacle on a transfer switch to provide
    | 120v power to both sides of the switch so I can use all 10 circuits. I
    | don't see a problem with this but I can't find anything about it after
    | many hours of searching the web. So what I plan is to use 2 120v outputs
    | from the generator and just double up the neutral and ground and then put
    | each hot lead on the separate hot leads of the the L14-30 thus giving the
    | same 120v to each side of the transfer switch. The generator is only 2300W
    | max, so I'm sure there won't be a problem using 12 or 14 AWG scrap
    | extension cord (SOJT 600V) for this. I'm trying to confirm I'm not missing
    | something. The generators ground is not common with neutral and the
    | transfer switch is a Connecticut Electric EGS107501A. I've already wired
    | the switch in and it works fine from the line side. Just need to get the
    | generator side hot.

    Is the generator producing only 120V or is it producing 120/240V?

    If the power source is 120V only, then in theory, by attaching that 120V
    source to both sides of a 120/240V system, the neutral could see the sum
    current of both legs. OTOH, your generator is so small that, even if it
    is just 120V only, we're looking at no more than 20A. As long as you use
    AWG #12 CU, it should be OK to connect your 120V hots to both sides of
    the system at the transfer switch. The switch MUST be an open-transition
    switch, which all small ones are. I can hardly imagine you getting one
    that is a closed-transition switch.

    Not that you'd even want to operate them on a 2300W generator, but I am sure
    you know this means your 240V appliances will see no voltage difference to
    speak of, if your generator is 120V only.

    FYI: my comments are not so much for the OP (he knows this stuff and is just
    looking for little things he may have overlooked like one duck out of row)
    but rather, for the newbies that might be reading this thread.

    BTW, isn't SOJT only 300V? Without the J then it would be 600V. But you
    aren't putting in 480/277 so the SOJT should be OK for 120V or 120/240V.
     
  3. Wes Newell

    Wes Newell Guest

    Only 120. Otherwise there wouldn't be a problem. I could just wire in a
    L14-30R on the panel.
    I didn't wire in any 240v circuits to the switch. Even If I replace the
    generator with a larger 240V one, I don't plan on wiring in any 240v house
    circuits. All I really care about is my frig, computer and TV circuits
    which I've already run off this generator for several days without any
    problems using pita extension cords. Hopefully, I can also get it to run
    at least one 5000BTU window AC that's rated at about 560W. If it will do
    that, I may put off getting a larger generator. I'm looking at a 6500W one
    that should run everything I really want without a problem. Basically, I'm
    feeling out what size I will eventually get. I could just get an 8KW one,
    but that sure seems like a waste for the amount of use it will get. Other
    than the 3 days without power about a year ago, we've never been without
    for more than 8 hours in the last 20 years here. I just want something
    easier than running extension cords when it's out for a few hours.
    Sorry, the cord is embossed "SJTO OIL RESISTANT 600 VOLTS E-18082". The
    wire appears to be 14. Certainly no smaller. Should be plenty big enough
    either way with no more than 15A on any one at a time. And the neutral and
    ground will be doubled to equal a lot more than needed. I should get the
    L14-30 Monday and will test it before the end of the week. Will let you
    know if there's a problem

    http://www.advdirect.com/index_003.htm

    Thanks for the reply.
     
  4. Wes Newell

    Wes Newell Guest

    Just a short follow-up. Got the L14-30 and wired it to the two 5-15's as
    described. Also determined the extension cord I had was indeed #12 wire.
    With the 2000W generator can run 2 small 5000BTU AC's (or one 12000BTU),
    Frig, and computer gear, and TV. Pretty much maxes out the 2000W but it's
    enough in an emergency. Enough that I'll wait til I can get a super deal
    on a larger one anyway.
     
  5. Guest

    | On Sun, 15 Jun 2008 20:43:32 +0000, Wes Newell wrote:
    |
    |> Sorry, the cord is embossed "SJTO OIL RESISTANT 600 VOLTS E-18082". The
    |> wire appears to be 14. Certainly no smaller. Should be plenty big enough
    |> either way with no more than 15A on any one at a time. And the neutral
    |> and ground will be doubled to equal a lot more than needed. I should get
    |> the L14-30 Monday and will test it before the end of the week. Will let
    |> you know if there's a problem
    |>
    | Just a short follow-up. Got the L14-30 and wired it to the two 5-15's as
    | described. Also determined the extension cord I had was indeed #12 wire.
    | With the 2000W generator can run 2 small 5000BTU AC's (or one 12000BTU),
    | Frig, and computer gear, and TV. Pretty much maxes out the 2000W but it's
    | enough in an emergency. Enough that I'll wait til I can get a super deal
    | on a larger one anyway.

    If this hurricane season passes with not a single named storm approaching,
    then maybe some of those generators will be available cheap.
     
  6. numeric

    numeric Guest

    Hurricane Wilma knocked out power here for about 18 days and used almost 40
    gallons (running for about 8 hours a day) of gas for a 5500W 110/220 volt
    generator. I could run the refrigerator, a few lights and the one of the
    following:

    1. Hot water heater. Took about an hour to heat up the water, but a warm
    shower is priceless.
    2. Use one "small burner" on the electric stove.
    3. Multiple 110 devices (lamps, ceiling fans, computer, garage door opener,
    1000 watt microwave, toaster oven) and most important, my 61 inch HDTV set
    ;-). I did not use the microwave and toaster oven at the same time. To save
    gas, used only what was necessary.

    The house AC would not run, need about 10 KW.

    I used a four conductor #6 gauge 25 foot cable to connect from the generator
    to the 220 volt dryer outlet; which powered the whole house. Threw the CB's
    off for the dryer, AC and a few others that need not be powered. Do not
    forget to throw the main circuit breaker off before connecting the
    generator. In an emergency you do what you got to do; however, I would like
    to find a better "whole house" power transfer system.
     
  7. numeric

    numeric Guest

    Oops.
    Un-plugged the dryer and left the circuit breaker on.
     
  8. Wes Newell

    Wes Newell Guest

    Unfortunately, there's no main breaker in my house. That's why I got the
    transfer switch. It works nicely for most of the house (6 15A, and 4 20A
    circuits).
     
  9. numeric

    numeric Guest

    Not even an outside circuit breaker after the power meter?
     
  10. Guest

    |
    | |> I didn't wire in any 240v circuits to the switch. Even If I replace the
    |> generator with a larger 240V one, I don't plan on wiring in any 240v house
    |> circuits. All I really care about is my frig, computer and TV circuits
    |> which I've already run off this generator for several days without any
    |> problems using pita extension cords. Hopefully, I can also get it to run
    |> at least one 5000BTU window AC that's rated at about 560W. If it will do
    |> that, I may put off getting a larger generator. I'm looking at a 6500W one
    |> that should run everything I really want without a problem. Basically, I'm
    |> feeling out what size I will eventually get. I could just get an 8KW one,
    |> but that sure seems like a waste for the amount of use it will get. Other
    |> than the 3 days without power about a year ago, we've never been without
    |> for more than 8 hours in the last 20 years here. I just want something
    |> easier than running extension cords when it's out for a few hours.
    |>
    | Hurricane Wilma knocked out power here for about 18 days and used almost 40
    | gallons (running for about 8 hours a day) of gas for a 5500W 110/220 volt
    | generator. I could run the refrigerator, a few lights and the one of the
    | following:
    |
    | 1. Hot water heater. Took about an hour to heat up the water, but a warm
    | shower is priceless.
    | 2. Use one "small burner" on the electric stove.
    | 3. Multiple 110 devices (lamps, ceiling fans, computer, garage door opener,
    | 1000 watt microwave, toaster oven) and most important, my 61 inch HDTV set
    | ;-). I did not use the microwave and toaster oven at the same time. To save
    | gas, used only what was necessary.
    |
    | The house AC would not run, need about 10 KW.
    |
    | I used a four conductor #6 gauge 25 foot cable to connect from the generator
    | to the 220 volt dryer outlet; which powered the whole house. Threw the CB's
    | off for the dryer, AC and a few others that need not be powered. Do not
    | forget to throw the main circuit breaker off before connecting the
    | generator. In an emergency you do what you got to do; however, I would like
    | to find a better "whole house" power transfer system.

    A transfer switch. The problem is this is difficult with "main breaker panels"
    as you would have a length of unprotected feed from the utility that you would
    be inserting the transfer switch into.

    One solution is a separate main breaker box. A transfer switch can be inserted
    between that box and the branch breaker panel. I'd ground this at the transfer
    switch, but I'm not sure a literal (or liberal) interpretation of the code would
    allow that (some inspectors might insist on grounding at the main breaker box
    since it is technically the service entrance).

    Another possibility is the double breaker transfer switch that locks out having
    both breakers on at the same time.

    This doesn't address automatic transfer switch systems. Those are more expensive.
     
  11. Wes Newell

    Wes Newell Guest

    Nope. Really sucked when I found this out. And I'd have had to do
    extensive work to add one. The transfer switch was cheaper and easier.
     
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