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  1. #1
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    Default Generator wiring

    I am trying to get an understanding of this system, but am a little confused. FYI - all of this wiring has permits, per the seller.

    We have the serive panel, the distribution panel, which is attached to the swtich panel for the generator.

    There is a 50 amp breaker in the service panel for the generator switch. It was hot - tested at 136 degrees when the rest of the box was 97 degrees. It cooled down later once the AC unit was turned off. I have two questions on this:

    1. Is this too hot for this breaker?
    2. What would cause it to run so hot? My thinking is that that there is a loose connection or wire somewhere.


    When they wired the distribution panel with the generator, they disconnected all the wires from the service panel, and now the service panel is being used as a raceway for these wires. Everything I know tells me that this is wrong. I am looking for verification and support on this.

    The distribution panel would be improperly bonded, as the grounds and neutrals are on the same bar.

    Any ideas on what else I might be missing. By the way, I did not test the generator. I put that outside the scope of my inspetion and suggested that an electrican test and verify the system.

    Thanks guys.

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    Bill Siegel
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  2. #2
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    Default Re: Generator wiring

    Bill,

    I'll address it this way as that is hard to follow (and I am missing finding where all the circuits go into the house, I was expecting to see it in the service equipment toward the bottom, but did not).

    There is an overhead service which is attached to the mast and goes to the meter.

    To the left of the meter is the service equipment, which includes the main disconnect and a service panel.

    (For now ignore the existing wiring involving the generator and that panel, instead presuming that those circuits are still in the service panel as was originally.)

    There are three small conduits which exit the bottom of the service equipment enclosure - where do all the other circuits go out at?

    Okay, follow that?

    (continued on next post)

    Jerry Peck, Construction / Litigation Consultant
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  3. #3
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    Default Re: Generator wiring

    Okay, from the above post an electrician comes in and sets a new panel to the left of the existing service equipment panel and an automatic transfer switch to the left of that.

    Being as that is not an automatic transfer switch with a built-in panel, it all needs to be wired per code, if that contained a built-in panel its wiring would be included within its listing and could have been quite different, making the wiring much easier to accomplish.

    The feeders from the service equipment to the automatic transfer switch should not have gone through the new panel, it should have been run directly to the automatic transfer switch.

    The generator has a disconnect breaker in it, as that is the power source and that breaker is the main disconnect for that power source, that main breaker in the generator becomes the service disconnect for the generator power.

    That makes the new panel not service equipment, so the neutral should not be bonded to ground at that panel (it is connected to the same terminal bar as ground).

    Also, I don't see any neutral conductors in that new panel for the 120 volt circuits which are in that panel - the neutral conductors are required to be run with the hot conductors. That is a big problem as to run the neutral conductors through that conduit it will exceed conduit fill, if it is not already exceeding conduit fill anyway.

    One of the problems you are commenting on is the branch circuit conductors for the emergency panel are now supplied by the generator and are running through the main service equipment panel, and that is not good (as you stated). Those circuits should be routed from the emergency panel to inside without going through the service equipment and its panel.

    It is wrong to run out of the panel from a breaker to another panel and then run back into and through the first panel, it is even more wrong to do so when the other panel is energized and the first panel is de-energized (supposedly - those conductors could easily re-energize the de-energized panel and back feed to not only the rest of the house but back into the overhead service - which is a BIG NO-NO.

    The more I look at that the more I see wrong with it - too many things to try to cover here.

    Jerry Peck, Construction / Litigation Consultant
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  4. #4
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    Default Re: Generator wiring

    Jerry,

    How then, could the city of Miami Shores have issued and passed this set up??

    Do you have any comments on the breaker being so hot?

    Bill Siegel
    Florida Home Inspection Team Inc.

  5. #5
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    Default Re: Generator wiring

    How then, could the city of Miami Shores have issued and passed this set up??
    WS: It is called "selective code enforcement".


  6. #6
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    Default Re: Generator wiring

    Quote Originally Posted by william siegel View Post
    Jerry,

    Do you have any comments on the breaker being so hot?
    Compressor could be drawing high current, might be on its way out!


  7. #7
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    Default Re: Generator wiring

    Doesn't look like the transfer switch is between the the SEC and the generator/service panel. Very dangerous!

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  8. #8
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    Default Re: Generator wiring

    Quote Originally Posted by william siegel View Post
    How then, could the city of Miami Shores have issued and passed this set up??
    Not being familiar enough with generator installations.

    I was confused about them too until I installed one at our house in South Florida, then the light came on and I understood it.

    Do you have any comments on the breaker being so hot?
    The breaker is not that hot, and isn't that the breaker which feeds all the circuits in the emergency panel?

    Jerry Peck, Construction / Litigation Consultant
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  9. #9
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    Default Re: Generator wiring

    Quote Originally Posted by Vern Heiler View Post
    Doesn't look like the transfer switch is between the the SEC and the generator/service panel. Very dangerous!
    Vern,

    That is one way to connect a generator ... if the generator is capable of supplying the ENTIRE load of the structure.

    When the generator is not capable of supplying the entire load of the structure, selected loads are supplied by an emergency panel, which is supplied by either utility power (under normal conditions) or generator power (under loss of utility power conditions).

    The key in this condition is TO NOT run back through the utility power panel and potentially risk energizing that panel, as that would do exactly what you said and would be VERY DANGEROUS to the utility company workers repairing the utility lines.

    There are panels made in which the panels themselves are designed to be operated from either utility power or generator power and, when on generator power, are self-adjusting in load distribution so as to not overload the capacity of the generator. Those are UL tested, listed, and labeled electrical equipment and are suitable for that use. They are also quite expensive.

    Jerry Peck, Construction / Litigation Consultant
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  10. #10
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    Default Re: Generator wiring

    Jerry, after closer look I see the sub-panel left of the service panel is supplied by the 240 breaker at the top left of the service. The sub is supplied by a back fed 240 breaker comming from the switch. I'd have to assume the switch is between the service and the sub. So the circuits in the sub-panel are the only circuits with back-up power. Ok with me on that. Don't know about rats nest of wires though?


  11. #11
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    Default Re: Generator wiring

    Quote Originally Posted by Vern Heiler View Post
    Jerry, after closer look I see the sub-panel left of the service panel is supplied by the 240 breaker at the top left of the service. The sub is supplied by a back fed 240 breaker comming from the switch. I'd have to assume the switch is between the service and the sub. So the circuits in the sub-panel are the only circuits with back-up power. Ok with me on that. Don't know about rats nest of wires though?
    Vern,

    Actually, it is not a "sub-panel" and not only because it is not in a submarine but also because it is THE panel when under generator power.

    It is, simply put, wired wrong.

    Jerry Peck, Construction / Litigation Consultant
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  12. #12
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    Default Re: Generator wiring

    Quote Originally Posted by Jerry Peck View Post
    Vern,

    Actually, it is not a "sub-panel" and not only because it is not in a submarine but also because it is THE panel when under generator power.

    It is, simply put, wired wrong.
    Ya got me .


  13. #13
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    Default Re: Generator wiring

    It may have been like a situation I had a couple of weeks ago. New home, intalled a manual switch for future use of a generator, I didn't know what size the generator was going to be and the new owner stated it would be a year or so before he purchased the generator.

    This might be the same scenario. They may have installed a generator that is not capable of supplying the amount of watts needed. That may be causing the breaker to overheat.


  14. #14
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    Default Re: Generator wiring

    "The breaker is not that hot, and isn't that the breaker which feeds all the circuits in the emergency panel?"

    Yes it is

    Bill Siegel
    Florida Home Inspection Team Inc.

  15. #15
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    Default Re: Generator wiring

    Quote Originally Posted by william siegel View Post
    "The breaker is not that hot, and isn't that the breaker which feeds all the circuits in the emergency panel?"

    Yes it is

    Bill,

    That means everything supplied by the emergency panel is running through that breaker when under utility power.

    Jerry Peck, Construction / Litigation Consultant
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  16. #16
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    Default Re: Generator wiring

    Quote Originally Posted by Jerry Peck View Post
    Bill,

    That means everything supplied by the emergency panel is running through that breaker when under utility power.
    As it should be. I take it from the earlier post, the this breaker running 30 degress hotter than the rest of the box is not a problem.

    Bill Siegel
    Florida Home Inspection Team Inc.

  17. #17
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    Default Re: Generator wiring

    Quote Originally Posted by william siegel View Post
    As it should be. I take it from the earlier post, the this breaker running 30 degress hotter than the rest of the box is not a problem.
    I would expect it to be hotter as it is carrying the load of the emergency panel circuits through it.

    Jerry Peck, Construction / Litigation Consultant
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  18. #18
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    Default Re: Generator wiring

    Quote Originally Posted by Jerry Peck View Post
    Bill,

    That means everything supplied by the emergency panel is running through that breaker when under utility power.
    Actually when under any power!

    The point that was made is that it cooled after the A/C was turned off. Merits investigation of the A/C current draw.


  19. #19
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    Default Re: Generator wiring

    Quote Originally Posted by Vern Heiler View Post
    Actually when under any power!
    Nope.

    The utility power energizes the automatic transfer switch from that breaker in the utility service power service equipment.

    When utility power is no longer present, the power to that breaker goes away, which allows the automatic transfer switch to "drop out" (it is basically a large contactor which is "held in" by the utility power), this now automatically switches from the utility power terminals to the generator power terminals, which now have power (the generator is now running) and supply those circuits in the emergency panel.

    There is no power through that breaker when running on generator power, i.e., the utility power service equipment is "dead" ... er ... SUPPOSED to be "dead", but now those circuits run back through that service equipment and therein lies the potential to re-energize parts of that utility power service equipment, and if any part of that utility power service equipment is re-energized, the service entrance conductors are re-energized, the meter is re-energized, the overhead service conductors are re-energized, and- through the transformer - the utility power lines are now re-energized.

    Yikes! To any utility worker working on restoring power!

    That is why plugging a generator into the dryer or range receptacle can be deadly for those workers - the house is re-energized (some circuits only if the homeowner thinks about what they are doing) and the service entrance conductors are re-energized, as is everything back out to, AND INCLUDING, the utility service. Only if the homeowner understands what is happening and what can potentially happen would they even think of turning the main breaker off and disconnecting the entire house from utility power are the utility lines not re-energized.

    That is why "transfer" switches are installed - automatic or manual - and they switch the neutral as well as the two hot legs ... this prevents any back feeding to the utility lines. Transfer switches "transfer" the complete path of power from one source to another.

    Many transfer switches where made which did not transfer the neutral, allowing for current to be sent back through the utility neutral, and when current goes through a resistance/inductance (the power lines, transformers, etc.) voltage is dropped across those items - meaning there is both voltage and current out there for the utility workers to grab onto, step onto, touch, etc.

    NOT GOOD!

    Jerry Peck, Construction / Litigation Consultant
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  20. #20
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    Default Re: Generator wiring

    Jerry, if you look at the pic's I think you will see that the power to the transfer switch comes from the double breaker on the left side of the service panel, goes into the bottom of the sub, then takes a hard left into the transfer switch. The red & black wires coming from the transfer switch feed the top left (back fed) main breaker in the sub. If this breaker does not get power there is no power to any of the circuits in the distribution panel (did that for you ). I agree that there is no way the xfer sw is switching the neutral and is not a good thing but don't see that as a very dangerous voltage path back to the SEC. That is the way it is in the diagram I found and posted.


  21. #21
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    Default Re: Generator wiring

    Oops! Just realized the breaker he was shooting with IR is in the main panel. I was talking about wrong breaker.


  22. #22
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    Default Re: Generator wiring

    not switching the neutral in considered a solid neutral - switching the neutral is called a serarately derived system.
    Start getting into separately derived systems and then you must get into grounding and bonding. This is because a separately derived system is considered another service. (Now you have a real complicated set up )


    You will find most emergency transfer switches are solid neutral - not switched.


  23. #23
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    Default Re: Generator wiring

    Quote Originally Posted by ken horak View Post
    not switching the neutral in considered a solid neutral - switching the neutral is called a serarately derived system.
    Start getting into separately derived systems and then you must get into grounding and bonding. This is because a separately derived system is considered another service. (Now you have a real complicated set up )


    You will find most emergency transfer switches are solid neutral - not switched.

    Looks like mine did NOT have a switched neutral as I remembered it as having (it's been 3-1/2 years since we moved - is that an acceptable excuse for not having remember correctly? ): we had the 13 kW NG / 15 kW LP model running on LP http://www.guardiangenerators.com/PublicPDFs/0D8846.pdf

    Jerry Peck, Construction / Litigation Consultant
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