Location of disconnect

morrisrv
morrisrv Registered Users Posts: 13 ✭
in Advanced Solar Electric Technical Forum #1
I will be installing a 10kw grid tie system soon(maybe) The house has an underground service, coming from the transformer pad located about 400' from house, meter is also located at this location. This so happens to be where th homeowner wants the array and is the best location, sun wise. Do to the large array anyway, I would like to tap into the "line" side of the service disconnect, as per 690.64 (A). I plan to come from the inverters to a fused disconnect then to the meter pan location and tap to the load side of meter, with either the proper tap connector or if lucky to the load side lugs if they are suitable for 2 wires. It will make the whole installation much more simple. Is there any issues with PV disconnect being located that far from the house service disconnect?
Thanks for any input in this issue,
Bob
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  • Roderick
    Roderick Solar Expert Posts: 253 ✭✭
    #2
    Re: Location of disconnect

    The authority on this matter seems to be the local utility company, not the usual City or Country inspectors.

    I'm no expert, but my lay expectation would be that if I turn off the main service disconnect at a residence, that everything is disconnected. I believe there is something in the NEC that says you should have a plaque or sign with a directory of all generating sources on the premises. Maybe that would cover this.

    PG&E *previously* had a requirement that the AC disconnect be within 10 feet of the meter, and clearly accessible (not behind a fence, locked door, etc). The requirement for an AC disconnect has since been waived for UL-1741 compliant inverters, but who knows what requirements another utility would still have in place? Also, I have to wonder, that in waiving the AC disconnect, someone had in their minds that the utility could always throw the main breakers open to disconnect everything if they had to, like for instance, to change the meter.

    Also, watch carefully for some threshold where the installation will be treated differently over a certain power level. Again, this depends on the jurisdiction. There might be a difference in the rules between a 9999-watt system, and a 10,000-watt system. Heaven forbid you get technically classified as a small wholesale generator. (I think for PG&E in California, the limits are much higher, for the record).
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #3
    Re: Location of disconnect

    Why couldn't you do a mobil home type service entrance. Ie Have the meter base and the main service disconnect at the transformer, and then have the main panel in the structure with another service disconnect. I don't know of any problem having redundant service disconnect.

    Icarus
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #4
    Re: Location of disconnect
    Roderick wrote: »
    someone had in their minds that the utility could always throw the main breakers open to disconnect everything if they had to, like for instance, to change the meter.

    So Cal Edison wanted my disconnect near the meter. I have underground feed from a pole in the yard. Flipping breakers in my panel, still leaves the meter energized, but with no current thru it. I had to screw a plaque to the breaker panel, and to the PV disconnect, stating it was fed from an "alternate" source.
    photo:
    http://forum.solar-electric.com/attachment.php?attachmentid=23&d=1188853683
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
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  • morrisrv
    morrisrv Registered Users Posts: 13 ✭
    #5
    Re: Location of disconnect

    Icarus, It is an existing house. If I put a new service disconnect out by the meter pad, then I must run a fourth wire into the house, very difficulte at this point. I am trying to interprete the NEC rule about having all the disconnects for a dwelling, up to 6, at the same location?
    Thanks everyone for your input,
    Bob
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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #6
    Re: Location of disconnect

    Bob,

    Here are John Wiles' comments on this issue from his "Photovoltaic Power Systems and the 2005 National Electical Code: Suggested Practices":
    MULTIPLE POWER SOURCES
    When multiple sources of power are involved, the disconnect switches shall be grouped and identified [230.72, 690.14(C)(5)]. No more than six motions of the hand will be required to operate all of the disconnect switches required to removeall power from the system [230.71]. These power sources include PV output, the battery system, any generator, and any other source of power. Multi-pole disconnects or handle ties should be used to keep the number of motions of the hand to six or fewer.

    Article 230 in the NEC allows each structure to have more that one source of supply. The sources might be a utility connection and a PV system. The disconnects of these two sources of supply do not have to be grouped [230.2, 230.71]. However placards are required showing where all of the disconnects are located [230.70, 690.54, 705.10].
    My take is that since you have multiple sources of power (utility and PV), but only one source of supply (the utility and PV system both feed the house via the same feeder line), the utility and PV disconnects will have to be grouped.
    HTH,
    Jim / crewzer
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  • morrisrv
    morrisrv Registered Users Posts: 13 ✭
    #7
    Re: Location of disconnect

    Jim,
    I had read the same article, thats when I started to get concerned!! I may call the utility and see if installing the proper signage will be OK. Really hoping not to dig up 400' of lawn to just put the PV AC disconnect at the house. As it is now, the design will have it next to utility meter.
    Thanks, Bob
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #8
    Re: Location of disconnect

    my general take on the same remote location shouldn't be a problem as long as how you do it all doesn't pose a problem to the utility and is all marked. this makes it easier on them and your local fire dept having everything in 1 spot as well as easier on you, but that last part of the equation they never cared about.
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  • Roderick
    Roderick Solar Expert Posts: 253 ✭✭
    #9
    Re: Location of disconnect

    Just musing.

    One way to avoid anyone possibly misunderstanding that the disconnect by the utility meter is just for the PV, and not the whole house, is to make it for the whole house. This could be done by using a really big switch, and connecting both the solar and the house to the load side of the switch, with the line side going back through the meter to the grid. This is where you ask the power company if this is a good plan or not, And besides, if you want to do it, you'll want them to send one of their people over to remove the meter temporarily, so you won't be working on live wiring when you install this big switch.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #10
    Re: Location of disconnect

    so you're thinking 2 switches then? kind of redundant, but i don't think they would object as it gives you a means of external disconnection in addition to their official disconnect. you never know with utilities though as one may say yes to that and another say no. utilities are free to go farther than the nec if they wish as are municipalities and cities so you can't just say to them anything reciting the nec as being law. some elect to not go by the nec at all too imposing their own rules. the point is, always check with the local government and the utilities as reason isn't always in a mix.
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