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Thread: How to Trouble shoot this???

  1. #16
    Licensed Electrical Contractor Speedy Petey's Avatar
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    Quote Originally Posted by Carl Simmo
    My question is how is this a danger for linemen if the MAIN and a couple others are thrown prior to plugging cable and starting generator? Is'nt the power isolated at that point?
    There are probably thousands of these widow maker setups out there. It only takes one mistake to kill a lineman. It can and DOES happen annually. Do YOU want to be responsible if someone messes with your setup and someone is hurt or killed???
    THAT is why this is an unacceptable setup.

  2. #17

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    You guys are the pro's so that's why I posted here and value your opinions. With that being said, I have an appointment w\ a local electrian for Sat.. He is gonna go over the transfer switch pricing with me and look at my other problem. What should I expect to pay for a install?

  3. #18
    DIY scratch-pad engineer leejosepho's Avatar
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    Quote Originally Posted by molo
    Could he also hire a responsible electrician ...?
    Well, I suppose so, but the work would not get done!

    Quote Originally Posted by Carl Simmo
    My question is how is this a danger for linemen if the MAIN and a couple others are thrown prior to plugging cable and starting generator? Is'nt the power isolated at that point?
    That was my own logic when I had a similar setup, but no, total isolation cannot be guaranteed as long as even only the common is still connected. I do not know why that is, and maybe someone else here can explain. However, the bottom line is that the simplest "Oops!" would send power out to the utility line and possibly cause damage or death.

    Look back at the link in HandyAndy's post. That kind of disconnect might be the least expensive way to go.

  4. #19
    Engineer Furd's Avatar
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    It is not a problem with the "common" lead (I think you meant to write neutral) but that there is no positive method of ensuring that the main breaker might not be closed when the generator is supplying power to the panel.

    The connecting cable between the generator and the panel, having a male plug on each end, is also a hazardous situation in that the possibility exists that it could be disconnected from the panel while the generator is running or disconnected from the generator when the panel is energized from the utility and either action would leave hazardous voltage on the male plug.

    Using a more conventional "extension cord" between the gennie and the panel is little better because in this case there would be a male plug or inlet connector that is connected to the panel by only a circuit breaker and the possibility exists that this "generator only" breaker could be closed while the panel is energized in the normal manner from the utility.

    In the above scenarios if the utility power is applied to the generator it will in all likelihood destroy the generator and in the process quite possibly severely hurt, or kill, anyone in the area.

    People will try to justify using such an arrangement as the original poster described by telling themselves, and anybody that will listen, that they would never make that mistake.

    People are far too often wrong.

    The ONLY acceptable method is one where the generator and the utility power can NEVER be connected at the same time. There are several different ways to do this and they include a 3-position transfer switch, a separate transfer panel and a circuit breaker interlock kit.

  5. #20
    In the Trades mattbee24's Avatar
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    If backfeeding through the neutral is a problem, then wouldn't a seperate panel with a breaker interlock be equally as dangerous?

  6. #21
    In the Trades Bob NH's Avatar
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    Square D sells a UL Listed interlock kit that permits the generator connection to be SAFELY backfed to the panel. It is available on E**y for about $70 + shipping.

    The neutral is not disconnected from the utility, and it is not disconnected in any of the "whole house" transfer switch installations that I have seen.

    You can also insert a disconnect outside there the generator connection will be make. The outdoor rated disconnects that are often used for Air Conditioner installations are quite inexpensive.

    The link below will take you to the other thread on this subject.

    http://www.terrylove.com/forums/showthread.php?t=15067

  7. #22
    DIY Member enosez's Avatar
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    Default Three phase two position disconnect???????????

    What about a three phase two position disconnect? Not that its code, but you can have utility power on one side, and generator power on the other. The three phase will let you disconnet even the neutral. Will get quite expensive though.

  8. #23
    Forum Admin, Expert Plumber Terry's Avatar
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    I bought a generator last Winter when we lost power for days.
    It was pretty inconvenient running cords everwhere.

    It's on my "to do" list to have an electritian come out and install a transfer switch on my panel.

    Last year I disconnected the furnace from the house wiring, and then when the power came back on, I had to rewire it.
    Yep, need a transfer switch.
    That would have been so much nicer.

  9. #24
    Rancher
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    You don't want to break the neutral, because it is also the ground at the power entrance panel, or if you do break it you need another ground rod at the disconnect switch.

    Rancher

  10. #25
    DIY Member MarkHash's Avatar
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    I once got a little tingle when I grabbed my camper pop up door at a campground. Thinking that was pretty strange, and before I let my wife enter the camper I got out my meter and poked one lead into the ground and the other to the door knob. I read the full 120 volts! It turned out that the electrician upstream had reversed the hot/neutral connection after wiring in a new rental cabin. I saved the day but this is certainly not an unheard of possibility with a back up generator setup.
    Last edited by MarkHash; 10-03-2007 at 09:47 AM.

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