AC disconnect requirement

Brent
Brent Solar Expert Posts: 64 ✭✭✭✭
in PV Installers Forum - NEC, Wiring, Installation #1
Hoping someone can point me in the right direction, Under existing CEC regs is it required to have a separate AC disconnect switch [throw handle type] in the circuit between the inverter AC output and load side connection to the service panel or is the service panel PV backfeed breaker sufficient for that purpose? The inverter does not have an AC disconnect capability and our utility company does not require a throw switch for AC disconnect.

Thanks,

Brent
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: AC disconnect requirement

    Code covers electrical safety. The breaker alone is a sufficient disconnect to meet this requirement.

    However in some jurisdictions an external 'accessible' disconnect may be required even though it serves no real purpose. This is because a lot of bureaucrats, inspectors, utilities, and fire departments do not understand that if you cut the grid to the house the GTI goes down.

    Now, in the case of a hybrid inverter they may be justified in having this separate disconnect so that no inverter-driven AC is available anywhere.

    In other words you have to check local code requirements.
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #3
    Re: AC disconnect requirement

    Yes my jurisdiction required it and requires it be labeled correctly as well
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  • Brent
    Brent Solar Expert Posts: 64 ✭✭✭✭
    #4
    Re: AC disconnect requirement

    Thanks for the quick reply. Our AHJ does not require a stand-alone AC disconnect so it looks like the backfeed breaker will do.

    Brent
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  • solarix
    solarix Solar Expert Posts: 713 ✭✭
    #5
    Re: AC disconnect requirement

    Around here, its required by the utility. They, being unionized, have safety regulations to the max and require an AC disconnect for lock-out, tag-out purposes.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #6
    Re: AC disconnect requirement

    from dave's pic seeing the holes for a lock present i am wondering if they allow for a lock on it to prevent vandals from throwing the switch. fireman and other workers that would have need to throw the switch should certainly be able to pop the lock.
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #7
    Re: AC disconnect requirement
    niel wrote: »
    from dave's pic seeing the holes for a lock present i am wondering if they allow for a lock on it to prevent vandals from throwing the switch. fireman and other workers that would have need to throw the switch should certainly be able to pop the lock.

    Actually that picture was taken before the Utility put a lock on it, note the remnants of the green AHJ sticker. The locks/PV meter seals appeared one day about a month after commissioning. I had problems with the disconnect not engaging properly once and had to pry the cover back as the utility said 4 days for service and if that was not my issue then a charge would ensue. I tested the line at the only 2 accessible points, the back-feed breaker and the AC combiner. The breaker showed 240 volts phase to phase, but the combiner did not. It was the problem and by prying the cover back it was easy to see that the arms were not fully engaged on one leg. We are still not sure who turned it off and then didn't slam the switch home, but it had to be the utility as they have the key. Of course they didn't admit anything. Really not sure why they even needed a lock on the disconnect but maybe it is the vandal issue, but the breaker panel is still fully accessible so that is a bit wrong headed.

    It was within a month or 2 after commissioning and someone at the utility probably got a bug about the bill dropping like a stone and their records were probably not updated yet. I will try and get a picture today with the lock in place.

    Edit:

    The only reason I can think of to seal and lock all that is to prevent any changes, like adding in more PV after commissioning. Heavier wire would need to be run to do that (sort of). It would be pretty easy to add about 10 amps of additional micro-inverters at the AC combiner without really doing an overload on the line, but personally I would prefer a heavier gauge wire in that case.
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  • solarix
    solarix Solar Expert Posts: 713 ✭✭
    #8
    Re: AC disconnect requirement

    Utility locks the AC disconnect for "safety" reasons, as it is easily accessible otherwise.
    People that move here from back east can't believe the common practice here of locating the service entry on the exterior of homes where anybody has access to it.
    Fire departments like it so they can kill the juice in event of fire though.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #9
    Re: AC disconnect requirement

    seems to me you are the owner of that box and should be able to put your own lock on it or they should've given you the key if they were to put a lock on it. you have a right to shut off your own power from your own disconnect. utilities, you can't with them and the 2nd part of you can't live without them does not apply to some here.:roll:
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  • solarix
    solarix Solar Expert Posts: 713 ✭✭
    #10
    Re: AC disconnect requirement

    The utility lock doesn't lock the disconnect handle from operating, it is put on the door tab that just prevents the door being opened.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #11
    Re: AC disconnect requirement

    oh ok as i thought he meant to the switch itself as that's what i was concerned with.

    do you have a provision to lock the handle dave?
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #12
    Re: AC disconnect requirement
    niel wrote: »
    oh ok as i thought he meant to the switch itself as that's what i was concerned with.

    do you have a provision to lock the handle dave?

    Solarix is right it just locks the box. There is a provision to lock the handle in the off position, but with a drill you could easily add an on position lock, it is just missing the hole to pass the lock through..

    Now I am glad I went and looked, damn cheap plastic flex connector has failed on the run to the back-feed breaker. Guess I need to call APS to get access to repair it. This is the only remaining piece of flex left from the original install, I hire Dodge Electric to replace all the rest of it with rigid. Guess I should have had this one done at the same time. :cry::cry::blush: Duh!

    :devil: Might be a prime time to upgrade the wiring back to the combiner box! ;) LOL
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #13
    Re: AC disconnect requirement

    Just wrap some duct tape around the gap.
    (Canadian standard repair.) :p:D
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  • peakbagger
    peakbagger Solar Expert Posts: 341 ✭✭✭
    #14
    Re: AC disconnect requirement

    I have one on my older system, The utility used to require them, but doesn't anymore for less than 10 KW. I need to hang a meter off my combined systems to sell SRECS so I plan to hook the new export meter off the disconnect box since it is mounted outdoors.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,637 admin
    #15
    Re: AC disconnect requirement

    Will your utility be "reading" the meter--Or do you self report?

    If the utility will be reading/using the meter, check with them for any additional charges--Second meters can really impact utility bills.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #16
    Re: AC disconnect requirement
    BB. wrote: »
    Will your utility be "reading" the meter--Or do you self report?

    If the utility will be reading/using the meter, check with them for any additional charges--Second meters can really impact utility bills.

    -Bill

    I know on mine they asked for a read once a year for the first couple years via a 3X5 post card, nothing since.
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  • SkiDoo55
    SkiDoo55 Solar Expert Posts: 414 ✭✭✭
    #17
    Re: AC disconnect requirement

    I would not think that the utility or the Fire Department would want a pad lock on the disconnect in the "ON" position. Here in PG&E country a A/C disconnect is not required, they will just pop the meter out of the socket to disconnect the whole house if needed.
    GT3.8 w/4600W Trina 230W, TX5000 w/5000W ET-250W, XW4024 w/1500W ET-250W, 4 L16, 5500W Gen. (never had to use) Yet!!
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  • peakbagger
    peakbagger Solar Expert Posts: 341 ✭✭✭
    #18
    Re: AC disconnect requirement

    With regards to my installation, the utility has no involvement with the "sell" meter I am currently net metered. NH requires an independent auditor to review the system to ensure that the meter accurately measures the generation and then after that I will need to send him a dated photo of the meter on occasion so he can report it. THe state also allows him to accept the web information available with many micro inverters.
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  • DarkAlchemist
    DarkAlchemist Registered Users Posts: 12 ✭
    #19
    Re: AC disconnect requirement
    SkiDoo55 wrote: »
    I would not think that the utility or the Fire Department would want a pad lock on the disconnect in the "ON" position. Here in PG&E country a A/C disconnect is not required, they will just pop the meter out of the socket to disconnect the whole house if needed.
    I always wondered about that first part but with darn children and pranksters around you need one and as far as the second part that is the way to go if you ask me. I am afraid of 240vac so when I work on replacing the main breaker I always pull the meter by breaking their tag (it is a tag that is there just to see if someone tampered with it) off and the next month they gripe at me then all is fine for 15 to 20 years more until I have to replace that breaker again.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #20
    Re: AC disconnect requirement

    You do not have to pull the meter to change a main breaker. Just switch everything (including the main) off. Nothing connected = no current flow = no problem. Yes the contacts will be live, but the risk of your actually touching them is minimal, and reasonable insulation measures (i.e. gloves and rubber soles) should do.

    No accounting for clumsiness, though. :D
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  • DarkAlchemist
    DarkAlchemist Registered Users Posts: 12 ✭
    #21
    Re: AC disconnect requirement
    Cariboocoot wrote: »
    You do not have to pull the meter to change a main breaker. Just switch everything (including the main) off. Nothing connected = no current flow = no problem. Yes the contacts will be live, but the risk of your actually touching them is minimal, and reasonable insulation measures (i.e. gloves and rubber soles) should do.

    No accounting for clumsiness, though. :D
    Better safe than sorry and when I say main breaker I mean there is nothing between the meter and my death. I prefer to err on the side of safety than to err 6 feet under.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #22
    Re: AC disconnect requirement

    Pulling meters (without permission) isn't a good idea either; the contacts in there are just as live as the ones in your panel box so the electrocution hazard is the same.

    Around here BC Hydro will accommodate you for any service work that requires power disconnect. And if you accommodate yourself by breaking the seal they'll pull the meter for you and never give it back. Might even drop the lines just to be sure.
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  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    #23
    Re: AC disconnect requirement
    Cariboocoot wrote: »
    Pulling meters (without permission) isn't a good idea either.

    And it must be a seal on the meter. If you break it, the electric company may claim you stole their electricity.
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  • DarkAlchemist
    DarkAlchemist Registered Users Posts: 12 ✭
    #24
    Re: AC disconnect requirement

    No electrocution hazard and I have done this across several electrical companies and not an issue. They can claim anything but then they would need to back it up AND I claim a kid did it. Works every time and way less hassle than having them do it because they charge.
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  • SkiDoo55
    SkiDoo55 Solar Expert Posts: 414 ✭✭✭
    #25
    Re: AC disconnect requirement
    DarkAlchemist wrote: »
    I always wondered about that first part but with darn children and pranksters around you need one and as far as the second part that is the way to go if you ask me. I am afraid of 240vac so when I work on replacing the main breaker I always pull the meter by breaking their tag (it is a tag that is there just to see if someone tampered with it) off and the next month they gripe at me then all is fine for 15 to 20 years more until I have to replace that breaker again.

    I am using they as in the fire department or the utility. Not the consumer. As mentioned if you break seal on meter then becomes issue with utility. Don't need to pull meter for main breaker change. Why are you changing main so offten? Call utility and they will pull it for you and reinstall and reseal without issue.
    GT3.8 w/4600W Trina 230W, TX5000 w/5000W ET-250W, XW4024 w/1500W ET-250W, 4 L16, 5500W Gen. (never had to use) Yet!!
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,637 admin
    #26
    Re: AC disconnect requirement

    I think he said it is 20+ years between pulling meter events... Perfectly normal. And my utility (Northern California) has never given me a hard time--I just call them and ask them to "reseal" the meter.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • DarkAlchemist
    DarkAlchemist Registered Users Posts: 12 ✭
    #27
    Re: AC disconnect requirement
    SkiDoo55 wrote: »
    I am using they as in the fire department or the utility. Not the consumer. As mentioned if you break seal on meter then becomes issue with utility. Don't need to pull meter for main breaker change. Why are you changing main so offten? Call utility and they will pull it for you and reinstall and reseal without issue.
    15 to 20 years outside and they give nothing but hassles and anything past the meter is my issue not theirs so they will pay for nothing past that meter.
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  • SkiDoo55
    SkiDoo55 Solar Expert Posts: 414 ✭✭✭
    #28
    Re: AC disconnect requirement
    DarkAlchemist wrote: »
    15 to 20 years outside and they give nothing but hassles and anything past the meter is my issue not theirs so they will pay for nothing past that meter.

    Had to change mine out at 42 years, Zinco breaker/load center mounted outside. Main buss bars corroding (coated aluminum) guess my climate is a little dryer. If you are just changing main breaker don't need to pull meter, unless you are changing the whole load center. At my location would require a permit so would have utility pull meter, no charge for that, then reinstall when completed.
    GT3.8 w/4600W Trina 230W, TX5000 w/5000W ET-250W, XW4024 w/1500W ET-250W, 4 L16, 5500W Gen. (never had to use) Yet!!
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