Can I connect Prosine 1800 to home breaker panel for backup power?

balee123
balee123 Solar Expert Posts: 86 ✭✭
in Off Grid Solar & Battery Systems #1
Hello,

I understand that there may be some potential problems with neutral bonded to ground with some inverters when inverters are connected to a home breaker panel. I do not know whether this is a problem with the inverter I have. I have acquired a TSW Prosine 1800 that has GFCI recepticle on inverter. If a manual transfer switch is put into the breaker panel, can this inverter be wired to the panel for backup power to power 1/2 (one leg) of the breaker panel? I would use a recessed "male receptical" wired to a 20 amp breaker connected to the transfer switch, and use an extension cord from the inverter when backup power is required.

Thanks for any information you can send my way.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #2
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?

    If it has a floating neutral then you will have a problem. Other wise the is no issue with feeding one side of the buss through a transfer switch with an inverter.

    a quick, and I note quick read of a PDF suggests that it is ok, but I would certainly read the true manual for your model.

    http://www.xantrex.com/documents/Power-Inverters/PROsine/Prosine%201000-1800%20Owner's%20Manual(445-0049-01-01_Rev-B).pdf

    Good luck,

    Tony
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #3
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?

    The non-GFCI Prosine 1800 can be used as such with no problems. It's a top of the line True Sine Wave inverter and it's Neutral can normally be grounded. Yours has the GFCI, and I expect the GFCI will trip off if the neutral is grounded at your panel, which is the usual way home breaker panels are wired. If it doesn't cause your GFCI to trip, you're home free.
    The "floating neutral" is mostly only an issue with MSW inverters, and grounding one of the MSW inverter AC output legs usually creates an instant smoke screen, however this can usually be cleared by opening the windows. Unfortunately, once a MSW inverter has produced a smoke screen, it will no longer produce any AC output. :D
    On another point, if you wire the Prosine's output to your manual transfer switch so it feeds both legs of the switch (assuming it's a two pole switch that totally transfers your panel from Grid to inverter), then when you switch over to inverter power, the inverter will feed in on BOTH legs of your breaker panel, providing 115 volts for everything in the house except for those items wired for 220 volts, which will then consume no power at all, as both legs will be the same in phase voltage.
    The only possible problem would be the GFCI tripping because of the neutral being bonded to ground in the panel. If you can bypass the GFCI, or if the Neutral is not grounded any place AFTER the GFCI, there would be no problem.
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  • Dill
    Dill Solar Expert Posts: 170 ✭✭
    #4
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?
    waynefromnscanada wrote: »
    The non-GFCI Prosine 1800 can be used as such with no problems. It's a top of the line True Sine Wave inverter and it's Neutral can normally be grounded. Yours has the GFCI, and I expect the GFCI will trip off if the neutral is grounded at your panel, which is the usual way home breaker panels are wired. If it doesn't cause your GFCI to trip, you're home free.
    The "floating neutral" is mostly only an issue with MSW inverters, and grounding one of the MSW inverter AC output legs usually creates an instant smoke screen, however this can usually be cleared by opening the windows. Unfortunately, once a MSW inverter has produced a smoke screen, it will no longer produce any AC output. :D
    On another point, if you wire the Prosine's output to your manual transfer switch so it feeds both legs of the switch (assuming it's a two pole switch that totally transfers your panel from Grid to inverter), then when you switch over to inverter power, the inverter will feed in on BOTH legs of your breaker panel, providing 115 volts for everything in the house except for those items wired for 220 volts, which will then consume no power at all, as both legs will be the same in phase voltage.
    The only possible problem would be the GFCI tripping because of the neutral being bonded to ground in the panel. If you can bypass the GFCI, or if the Neutral is not grounded any place AFTER the GFCI, there would be no problem.


    Wayne is spot on, I have a similar setup with a 1500 watt Samlex inverter in my garage along with a Reliance Controls transfer switch with remote input. It works great, and I can move circuits between inverter and grid power as my battery levels rise and fall. The GFCI outlet on the inverter caused me grief so I replaced it with a standard electrical outlet.
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  • balee123
    balee123 Solar Expert Posts: 86 ✭✭
    #5
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?
    waynefromnscanada wrote: »
    ...On another point, if you wire the Prosine's output to your manual transfer switch so it feeds both legs of the switch (assuming it's a two pole switch that totally transfers your panel from Grid to inverter), then when you switch over to inverter power, the inverter will feed in on BOTH legs of your breaker panel, providing 115 volts for everything in the house except for those items wired for 220 volts, which will then consume no power at all, as both legs will be the same in phase voltage.
    The only possible problem would be the GFCI tripping because of the neutral being bonded to ground in the panel. If you can bypass the GFCI, or if the Neutral is not grounded any place AFTER the GFCI, there would be no problem.

    Thanks for the info. I was reading somewhere that there could be potential problems feeding both legs off one power source (same 120V source). Something about if one circuit on each leg shares a neutral (apparently a common thing?), that the neutral line "could be overloaded".......I'm not sure exactly what this means, since aren't all neutrals "shared" as they are tied to each other and the ground in the panel? If someone understands this can they describe what it would look like?
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  • Dill
    Dill Solar Expert Posts: 170 ✭✭
    #6
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?

    this isn't possible with your inverter because it's maximum output is 15 amps at 120 volts. The situation you mentioned can occur by sharing a neutral line with 2 hots, therefore putting more than 15 amps on that neutral line, but as I mentioned above, the maximum output of your inverter is only 15 amps so that cannot happen.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #7
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?
    Dill wrote: »
    this isn't possible with your inverter because it's maximum output is 15 amps at 120 volts. The situation you mentioned can occur by sharing a neutral line with 2 hots, therefore putting more than 15 amps on that neutral line, but as I mentioned above, the maximum output of your inverter is only 15 amps so that cannot happen.

    EXACTLY!
    If however your power supply was powerful enough to overheat household wring when under full load, then yes, two hots sharing one neutral could well be a problem, but that's not a worry with the Prosine 1800 and smaller inverters.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #8
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?

    A simple way to look at the shared neutral issue.

    Take this situation. Let's say you have 2 15 amp circuits each wired on opposite busses if a split phase panel, wired with a home run of 14/2 romex. Each hot leg could carry 15 amps, but the neutral would carry only 15 amps at any one time because each load would be 180 degrees out of phase, leaving a net (max)load on the neutral of only 15 amps.

    Now, if these two circuits were energized by the same buss (same phase) each hot could carry 15 amps, while the neutral COULD carry a full 30 amps, because each hot is in the same phase. In the case of your inverter, you could energize both from the same leg, but because the inverter only produces LESS than 15 Amps, there is no danger of overloading the neutral.

    I suspect it is not a strictly "legal" installation, but assuming the inverter CANNOT produce more power than the wire is rated for, then it would certainly be a "safe" installation. The problem, as I see it, would be if you wire it that way, and at some point in the future increase the size if the inverter without remembering how 3 wire circuits were wired, you could conceivably overload the neutral(s).

    Clear as mud?

    Tony
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #9
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?
    balee123 wrote: »
    Thanks for the info. I was reading somewhere that there could be potential problems feeding both legs off one power source (same 120V source). Something about if one circuit on each leg shares a neutral (apparently a common thing?), that the neutral line "could be overloaded".......I'm not sure exactly what this means, since aren't all neutrals "shared" as they are tied to each other and the ground in the panel? If someone understands this can they describe what it would look like?

    I don't think your actual question about how this happens has been answered yet, (You snuck in as I was writing, Tony/icarus) so here goes:
    **** Super Moderators all look the same to me*****
    Imagine a 240 volt panel, with two 120 volt hot line terminals, L1 and L2, and common neutral. In normal grid connected use, the worst case current on the neutral will be when all loads are on one side, say L1. Then the entire current that flows out of L1 must return on the neutral, N. Same if all of the loads are only on L2.
    Then when you add either 240 volts loads (wired L1 to L2) or a balance of loads on L1 and L2 the current through the neutral will go DOWN, because the phase of the return currents in N from L1 and L2 are opposite so the currents subtract. You can think of this as the current just flowing from L1 to L2 and not through N at all.

    But when you connect both L1 and L2 to the same 120 volt phase two things happen:
    1. 240 volts loads will not work, because they see only 0 volts from L1 to L2, and
    2. The balanced 120 volt loads on L1 and L2 both produce current in N which no longer cancels. Potentially you have twice the current in N as you have in either L1 or L2. Since the circuit breakers are in L1 and L2 only, there is nothing to protect N from the 2X overload.

    As has been stated, if the capacity of the alternate power source is entirely within the current rating of the N wire, there is no problem.

    On the house side of the distribution panel, there may be what is called a multi-wire branch circuit in which two sets of 120 volt outlets or wired loads, one connected to L1 and one connected to L2 share a common Neutral wire. The same problem of a 2X overload can happen there.
    Multi-wire branch circuits (MWBC) (also called Edison circuits) are not as common in residential wiring as they used to be, as the savings in wire cost is minimal that the maintenance problems are irritating. (For example of you turn off the L1 side breaker of a MWBC, thinking that you have de-energized the circuit, and then open the shared neutral wire, you will suddenly find 120 volts from L2 on the neutral wire. Bad for the electrician, worse for the DIY'er!) Shared neutrals also cannot be used with GFCI circuit breakers.
    SMA SB 3000, old BP panels.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #10
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?

    Hey Tony! He's calling you a "coot"! I wouldn't take that if I were you! :p
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #11
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?

    I resemble that remark!

    It takes a lot more to insult me,,,

    Tony
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  • balee123
    balee123 Solar Expert Posts: 86 ✭✭
    #12
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?

    So for arguement sake.................if you had two Prosine 1800's and used them to energize one leg each, could this cause issues?

    If shared neutrals exist.............there could be problems, right?

    Assuming no shared neutrals........... shouldn't be a problem, correct?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #13
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?

    Yes--In theory, you could have the two inverters in phase instead of 180 degrees out of phase--meaning the currents of the shared neutral will add... In practice--don't know how precise the frequency is on the inverters and they probably will not start in a "known" phase relationship--and sometimes electronics can beat against each other and achieve a sort of phase lock (again--don't know if in/out/random phase lock or not).

    The can share a common neutral bus bar/ground strap--But the hots to load and neutral to loads should be run in Hot/Neutral pairs, not two hots and a neutral because of the lack of known/controlled phasing between the two independent 120 VAC inverters.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • balee123
    balee123 Solar Expert Posts: 86 ✭✭
    #14
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?
    Dill wrote: »
    Wayne is spot on, I have a similar setup with a 1500 watt Samlex inverter in my garage along with a Reliance Controls transfer switch with remote input. It works great, and I can move circuits between inverter and grid power as my battery levels rise and fall. The GFCI outlet on the inverter caused me grief so I replaced it with a standard electrical outlet.

    Wayne and Dill were right. My GFCI outlets trip when I try to energize my breaker panel. I thought I would try to swap out the GFCI outlet for a standard one, however, after opening up the Prosine 1800, it does not look that easy. The wiring to this outlet does not appear to be standard and looks difficult to remove.

    Are there other ways to prevent the GFCI outlet from tripping? What other options do have?

    Is there a way to still use the GFCI outlet on this inverter and still energize the breaker panel?

    Thanks in advance.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #15
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?
    balee123 wrote: »
    Wayne and Dill were right. My GFCI outlets trip when I try to energize my breaker panel. I thought I would try to swap out the GFCI outlet for a standard one, however, after opening up the Prosine 1800, it does not look that easy. The wiring to this outlet does not appear to be standard and looks difficult to remove.

    Are there other ways to prevent the GFCI outlet from tripping? What other options do have?

    Is there a way to still use the GFCI outlet on this inverter and still energize the breaker panel?

    Thanks in advance.

    Remove the GFCI outlet. Problem ended.
    They aren't the miracle safety device some might have you believe.
    The reason they put them on these small inverters is because they expect you will just plug something in to the outlet. In that situation you have a GFCI protected outlet much as you would find in any home. Trying to run everything else through it ... becomes a problem. Slight variations causes by all that extra wiring adds up to differences that are enough to trigger the GFCI.
    If you need the ground-fault protection (outlets at wet sites) put it where it is used. It will work better that way.
    And note that this is not the same as a GFCI breaker in a service panel which is protecting one circuit only.
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  • balee123
    balee123 Solar Expert Posts: 86 ✭✭
    #16
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?

    Thanks for the reply. From reading other threads, this does appear the best thing to do, however, when I open the Prosine, the GFCI outlet seems tied/soldered to small circuit board. Also, the hot and neutral lines are not attached to the side connection screws. To me it seems like it would be difficult to remove.

    Can I bypass the GFCI in some other way, without physically removing it?

    I'm guessing something like this would not work, or cause other problems, or even be dangerous?


    Attachment not found.
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #17
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?
    balee123 wrote: »
    Thanks for the reply. From reading other threads, this does appear the best thing to do, however, when I open the Prosine, the GFCI outlet seems tied/soldered to small circuit board. Also, the hot and neutral lines are not attached to the side connection screws. To me it seems like it would be difficult to remove.

    Can I bypass the GFCI in some other way, without physically removing it?

    I'm guessing something like this would not work, or cause other problems, or even be dangerous?


    Attachment not found.

    Yes, absolutely, ground lift blocks can be dangerous.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #18
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?
    ggunn wrote: »
    Yes, absolutely, ground lift blocks can be dangerous.

    The only other way I can see to make this work, without tapping into the inverter directly for hard-wiring, would be to add a second neutral bar to the breaker panel so that you can remove jumper wires and isolate the two sets of neutrals from each other and from ground.

    The neutrals from one Line/phase bus would go to one bar and the neutrals for the other would go to the new bar. You would then have to make the neutral to ground bond at each of the inverters.

    But that would be so counter to NEC with the jumpers removed that it could be a bad idea. Forget to put them back in when returning to POCO power, and all sorts of bad things could happen.
    SMA SB 3000, old BP panels.
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  • balee123
    balee123 Solar Expert Posts: 86 ✭✭
    #19
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?
    Cariboocoot wrote: »
    Remove the GFCI outlet. Problem ended.
    They aren't the miracle safety device some might have you believe.
    The reason they put them on these small inverters is because they expect you will just plug something in to the outlet. In that situation you have a GFCI protected outlet much as you would find in any home. Trying to run everything else through it ... becomes a problem. Slight variations causes by all that extra wiring adds up to differences that are enough to trigger the GFCI.
    If you need the ground-fault protection (outlets at wet sites) put it where it is used. It will work better that way.
    And note that this is not the same as a GFCI breaker in a service panel which is protecting one circuit only.

    Here are a couple of pictures of the back of the GFCI outlet. The small circuit board that I mentioned is shown prominently. The hot and neutral lines in picture #1 on the right hand side come from the inverter proper. Any idea what this circuit board is for?

    If I can remove the outlet, should I just wire the hot and neutral lines coming directly from the inverter to the new outlet and ground the new outlet to the chassis?

    Attachment not found.

    Attachment not found.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #20
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?
    waynefromnscanada wrote: »
    The non-GFCI Prosine 1800 can be used as such with no problems. It's a top of the line True Sine Wave inverter and it's Neutral can normally be grounded. Yours has the GFCI, and I expect the GFCI will trip off if the neutral is grounded at your panel, which is the usual way home breaker panels are wired. If it doesn't cause your GFCI to trip, you're home free.

    The off-the-shelf solution to your problem (not counting just running lots of extension cords :-)) is to use a circuit-by-circuit transfer panel similar to the ones available from Generac.

    For these you can run the hot leads disconnected from each circuit breaker, a wire going to the breaker, AND the neutral lead for the corresponding circuit into the switch panel and transfer them both to one or the other Prosine depending on how you wire it. The standard Generac panel does not switch the neutrals, as I recall, so you would have to customize something and then the NEC would be out the window anyway.

    Since you either do not need 240 loads or will not be able to power them anyway, using one inverter for both legs of the main panel would avoid the problem. But would limit your power correspondingly.
    SMA SB 3000, old BP panels.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #21
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?
    balee123 wrote: »
    Here are a couple of pictures of the back of the GFCI outlet. The small circuit board that I mentioned is shown prominently. The hot and neutral lines in picture #1 on the right hand side come from the inverter proper. Any idea what this circuit board is for?

    If I can remove the outlet, should I just wire the hot and neutral lines coming directly from the inverter to the new outlet and ground the new outlet to the chassis?

    These pictures appear to be a standard GFCI outlet wired through the "poke-and-hope" connections with a circuit board in-between. The board seems to have three small caps on it? Probably wired across Hot-Neutral, Hot-Ground, and Neutral-Ground. They might be MOV's to nip transients. My eyes are too old to see them clearly. Looks like they ran the wiring through a ferrite choke too, trying to cut some noise perhaps?

    So it's a matter of how comfortable are you with disconnecting 120 VAC wires?
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  • balee123
    balee123 Solar Expert Posts: 86 ✭✭
    #22
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?

    Thanks to all that contributed to answering my questions. With some difficulty I was able to remove the GFCI outlet and replace it with a standard outlet that had those "poke and hope" holes that were mentioned. It was a pain with my larger hands, but after screwing around this afternoon, I finally got it put together and it works to energize the breaker panel, at least one leg for now. Not tripping.............Another problem I had was finally realizing that there was a lot of this "solidified goop" kind of like cured silicone caulk that had stuck to the GFCI in several places. Had to cut through this stuff with an Exacto blade to finally get the sucker removed.

    Again thanks to all. Happy Camper here :D
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #23
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?
    balee123 wrote: »
    Are there other ways to prevent the GFCI outlet from tripping? What other options do have?

    Is there a way to still use the GFCI outlet on this inverter and still energize the breaker panel?
    You can solve your problem with an isolation transformer. I mention this only because you asked. Replacing the GFCI (which I see you have done) is much more cost effective.
    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • Dill
    Dill Solar Expert Posts: 170 ✭✭
    #24
    Re: Can I connect Prosine 1800 to home breaker panel for backup power?

    glad it worked out for you, I did the same thing, unsoldered the GFCI outlet..
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