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    Inverters and 110.26

    Greetings all we frequently install SMA 'Sunny Boy' inverters.
    I have always considered inverters to fall under 110.26 rules for working clearance, and it usually is not a problem to meet 110.26.
    Currently we have a project where a inverter is going to be installed in a laundry room in a multi family complex and the 'best' place to put the inverter is on the wall behind a cloths washer.
    Now that PV systems have a Rapid Shutdown/DC disconnect initiator and I am wondering if 110.26 applies to inverters any more? (or ever did) as you would could safely de-energize the inverter from both AC and DC before servicing it.

    I guess my question is two part
    A) does a 'DC disconnect initiator' qualify as a 690 Part III. Disconnecting Means:
    690.13 "Photovoltaic System Disconnecting Means. Means
    shall be provided to disconnect the PV system from all wiring
    systems including power systems, energy storage systems, and
    utilization equipment and its associated premises wiring.
    (A) Location. The PV system disconnecting means shall be
    installed at a readily accessible location."
    and
    B Are there any other provisions in 690 that require working space around an inverter?
    Thanks in advance.
    Comments based on 2017 NEC unless otherwise noted.

    #2
    Yes, it applies to the inverter, always has. Behind the washer is not going to be code compliant.

    Comment


      #3
      Originally posted by pv_n00b View Post
      Yes, it applies to the inverter, always has. Behind the washer is not going to be code compliant.
      Thanks for the reply are you just going off 110.26 in general?
      I was just looking at 705.70:

      705.70 Interactive Inverters Mounted in Not Readily Acces-
      sible Locations. Interactive inverters shall be permitted to be
      mounted on roofs or other exterior areas that are not readily
      accessible. These installations shall comply with (1) through (4):
      (1)A dc disconnecting means shall be mounted within sight
      of or in the inverter.
      (2)An ac disconnecting means shall be mounted within sight
      of or in the inverter.
      (3)An additional ac disconnecting means for the inverter shall
      comply with 705.22.
      (4)A plaque shall be installed in accordance with 705.10.
      Comments based on 2017 NEC unless otherwise noted.

      Comment


        #4
        705.70 has nothing to do with working space.

        With most string and central inverters it strains credulity to argue that you will never have to examine them while energized. Just about any trouble shooting will require taking voltage readings in an open disconnect section. Microinverters are an exception since there's nothing to open up.

        Comment


          #5
          Originally posted by tortuga View Post
          Thanks for the reply are you just going off 110.26 in general?
          I was just looking at 705.70:
          There's a big difference between it being in a "not readily accessible location" because you have to remove obstacles, vs because you have to get a portable ladder to get to it. Especially an appliance that is a 2-person job to move out of the way. We all see nature fill the vacuum of working space from building user habits, but it should at least start correctly without any intentional device occupying the space.


          That article about inverters in "not readily accessible locations" was meant for inverters in locations, where you need a portable ladder to get to the inverter. Flat roof systems where you need a portable ladder to get through the hatch, or carport column where it is intentionally out of reach from the general public. Not inverters where an appliance is in the way.

          Comment


            #6
            Thanks for both of your thoughts I admit its not an ideal situation, buts its the owners preference and its a public laundry room for a multifamily complex, not a residential laundry room.
            The only other location it could go (with proper working space) would make it a likely head knocker with a low washer door bordering the side of the working space.

            Or at greater expense to the owner putting it outside.

            I can make the case 110.26 sub paragraph (A) does not apply, as its unlikely it would need to be accessed while energized. There are two disconnects you can stand in front of and take voltage readings.
            If you got DC going in and no AC coming out, the inverter is likely getting replaced.
            One would not need to reach the inverter quickly during a emergency, as its just equipment at this point since there are "Readily Accessible" disconnects to de-energize it within sight.

            110.26, the first paragraph seems to require general access to equipment but not ready access:
            110.26 Spaces About Electrical Equipment. Access and working space shall be provided and maintained about all electrical
            equipment to permit ready and safe operation and maintenance
            of such equipment.
            .
            The case that would would need to be made is that the inverter is 'accessible' as defined by the NEC if all you need to do is move a large washer out of the way.



            While it makes a great deal of common sense as you both point out to put the inverter in a 110.26(A) location I am not seeing a specific NEC requirement (in the 705) for an inverter to be "Readily Accessible".
            And I think that behind a washer it will get no tampering from the public.

            Currious if you all have more thoughts?
            Thanks
            Comments based on 2017 NEC unless otherwise noted.

            Comment


              #7
              Originally posted by tortuga View Post
              Thanks for both of your thoughts I admit its not an ideal situation, buts its the owners preference and its a public laundry room for a multifamily complex, not a residential laundry room.
              The only other location it could go (with proper working space) would make it a likely head knocker with a low washer door bordering the side of the working space.

              Or at greater expense to the owner putting it outside.

              I can make the case 110.26 sub paragraph (A) does not apply, as its unlikely it would need to be accessed while energized. There are two disconnects you can stand in front of and take voltage readings.
              If you got DC going in and no AC coming out, the inverter is likely getting replaced.
              One would not need to reach the inverter quickly during a emergency, as its just equipment at this point since there are "Readily Accessible" disconnects to de-energize it within sight.

              110.26, the first paragraph seems to require general access to equipment but not ready access:

              .
              The case that would would need to be made is that the inverter is 'accessible' as defined by the NEC if all you need to do is move a large washer out of the way.



              While it makes a great deal of common sense as you both point out to put the inverter in a 110.26(A) location I am not seeing a specific NEC requirement (in the 705) for an inverter to be "Readily Accessible".
              And I think that behind a washer it will get no tampering from the public.

              Currious if you all have more thoughts?
              Thanks
              All I can say is that I do not believe that such an installation would pass inspection with any of the AHJs I deal with.

              Comment


                #8
                Thanks ran this by the AHJ, awaiting him to contemplate it also.
                I am not enough of a solar guru to point to a code section that prohibits it.
                Comments based on 2017 NEC unless otherwise noted.

                Comment


                  #9
                  Originally posted by tortuga View Post
                  Thanks ran this by the AHJ, awaiting him to contemplate it also.
                  I am not enough of a solar guru to point to a code section that prohibits it.
                  This has little to do with solar per se.

                  Comment


                    #10
                    Originally posted by ggunn View Post
                    This has little to do with solar per se.
                    Well the interactive inverters marketed for solar often contain AFCI's and other overcurrent devices.
                    What my AHJ and I have concluded is an interactive inverter does not require working space as long as its:
                    1) Accessible without the use of tools
                    or modifying building finish.
                    2) Not likely to require examination, adjustment,
                    servicing, or maintenance while energized.
                    3) Contains no fuses or circuit breakers including AFCI's.
                    Comments based on 2017 NEC unless otherwise noted.

                    Comment


                      #11
                      As I said above, (2) is going to be hard to come by.

                      Comment


                        #12
                        Originally posted by jaggedben View Post
                        As I said above, (2) is going to be hard to come by.
                        Well this case is closed for me now, AHJ approved.
                        Some of these interactive inverters are kinda of a set it and forget it system, you could put one up in a drop ceiling like a transformer IMO. They have a ethernet port and just plug in to a buildings network. All the settings you need from a web interface.
                        The key word the AHJ looked at in 110.26(A) is "likely".
                        There was nothing in the inverter manual about regular maintenance while energized.
                        There would be no need for an emergency responder to access the inverter quickly.
                        With all the new requirements around DC rapid shutdown there is not really much NEC concern about the inverter.

                        Now an Outback Power off grid inverter, like I used to see thats another story, they had built in over-current devices, those are basically a mini load center.
                        Comments based on 2017 NEC unless otherwise noted.

                        Comment


                          #13
                          I can't tell you how many times I've had to service an inverter and troubleshoot it with either AC or DC energized and the cover off. You're working with an AHJ who's ignorant about solar, is about all I have left to say. Lucky for you, I guess. Man, if our company could have the money back from every time we failed an inspection over the years because our installers didn't diligently measure the working space...

                          Comment


                            #14
                            Originally posted by jaggedben View Post
                            I can't tell you how many times I've had to service an inverter and troubleshoot it with either AC or DC energized and the cover off. You're working with an AHJ who's ignorant about solar, is about all I have left to say. Lucky for you, I guess. Man, if our company could have the money back from every time we failed an inspection over the years because our installers didn't diligently measure the working space...
                            Likewise. We'd never have gotten away with that one in any jurisdiction I know of.

                            Comment


                              #15
                              Originally posted by jaggedben View Post
                              I can't tell you how many times I've had to service an inverter and troubleshoot it with either AC or DC energized and the cover off. You're working with an AHJ who's ignorant about solar, is about all I have left to say. Lucky for you, I guess. Man, if our company could have the money back from every time we failed an inspection over the years because our installers didn't diligently measure the working space...
                              While I agree some inverters may need to be examined while energized, and as a field electrician your the one doing all of this quite often (hopefully with proper PPE!).

                              In my opinion for 110.26(A) to legally apply with the 2017 NEC as it stands, it would have to be likely that most inverters would need to be examined while energized, like you would a service disconnect or a battery bank.

                              There are many things electricians may choose to examine or test while energized, junction boxes,transformers, motors, phase converters and none of them require 110.26(A) working space.
                              If a piece of equipment is having a problem you can de-energize the equipment from a 110.26(A) location and do what you need to do to create a safe working space to re-energize for examination and testing.

                              The AHJ has seen quite allot of solar, however there is a law in Oregon that inspectors have to cite a particular section of code if they are going to fail an inspection, and the state makes code interpretations on a state wide basis. I would never try to pull one over on him, that would ruin our relationship. He knows that if I am the designer on a job I am going to push hard for what our client wants, and our client is a small solar company.

                              All this being said, I really appreciate both of your input as it gives me a sense of standard practices around the country, and Ill press for a common sense location as it was just a plan that got approved.
                              Comments based on 2017 NEC unless otherwise noted.

                              Comment

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