X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    Originally posted by Sunking View Post

    Your Installer will provide a Down Conductor(s) to bond the frames with and run them outside the house to your utility service ground. By installing to code is more than sufficient protection against lightning.
    How the requirement is interpreted will vary from one AHJ to the next. Around here, the interpretation of 2014 690.47(D) for roof mounted arrays seems to be that exception 2 allows the EGC from the array to the inverter to serve all grounding needs if it meets GEC standards. This didn't change much in 2017 NEC, again with only the EGC for fault protection required, and an auxiliary electrode (and conductor) being permitted by 690.47(b), but not required.

    If the OP wants a short, fat, straight down conductor, outside the structure, it is not safe to assume the installer will put one in, especially since the home run (including the egc) is being run through the attic and the walls.
    Last edited by sensij; 08-08-2017, 11:48 PM.
    CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

    Comment


    • #17
      Originally posted by JRqwertyui View Post
      ....
      I'm also requesting the conduit be run inside the attic space below the upper roof where the panels will be installed, down a chase way over the garage and out to the subs and main panel... any concerns regarding the conduit runs inside the house instead of over the roof, through the eave, and down along side of the house (which I consider unappealing) ?.........
      If you are worried about lightning, I would NOT run (invite the lightning path) the conduit inside the building envelop. Think of lightning like a Slot Car (remember them?) You want smooth easy routing from the roof to the ground rod. Where there is a sharp bend, the charge will ignore it (cable bends are "inductors" at high frequencies) and "jump the track" and continue to Earth the way it wants to.

      Powerfab top of pole PV mount (2) | 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 ||
      || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

      solar: http://tinyurl.com/LMR-Solar
      gen: http://tinyurl.com/LMR-Lister

      Comment


      • #18
        Originally posted by sensij View Post
        How the requirement is interpreted will vary from one AHJ to the next. Around here, the interpretation of 2014 690.47(D) for roof mounted arrays seems to be that exception 2 allows the EGC from the array to the inverter to serve all grounding needs if it meets GEC standards. This didn't change much in 2017 NEC, again with only the EGC for fault protection required, and an auxiliary electrode (and conductor) being permitted by 690.47(b), but not required..
        Wow your local AHJ did not amend 690.47 out of the local code?

        First AHJ I have heard that will let you use EGC. That is flat out dangerous, not to mention stupid. .

        MSEE, PE

        Comment


        • #19
          Originally posted by Mike90250 View Post
          If you are worried about lightning, I would NOT run (invite the lightning path) the conduit inside the building envelop.
          Ditto, you just sat out the Welcome Sign for Lightning to come on in and make yourself at home.

          MSEE, PE

          Comment


          • #20
            Originally posted by Sunking View Post
            Wow your local AHJ did not amend 690.47 out of the local code?

            First AHJ I have heard that will let you use EGC. That is flat out dangerous, not to mention stupid. .
            Remember the two rules. Still, if I ever thought something an inspector said or wanted changed produced a dangerous situation, and we couldn't work it out, I'd start climbing the chain of command after advising the inspector of my intentions. Done that a couple of times, both of which were for pressure vessel equipment designs requiring nuclear stamp. I batted 0.500 in that league.

            Comment


            • #21
              Originally posted by J.P.M. View Post
              Remember the two rules. Still, if I ever thought something an inspector said or wanted changed produced a dangerous situation, and we couldn't work it out, I'd start climbing the chain of command after advising the inspector of my intentions. Done that a couple of times, both of which were for pressure vessel equipment designs requiring nuclear stamp. I batted 0.500 in that league.
              Not so much talking about a person. Local Jurisdictions, say San Diego, can accept or reject any NEC codes. They can even make up their own rules as many cities like Chicago do.

              690.47(D) is the only code written known to be dangerous to public safety. That is what happens when you let advocates get involved with something. In thi scase John Wiles from NMSU and Sandia National Labs. John pretty much srote 690. Anyway 690.47(D) intention is to save the homeowner significant installation cost. That is it plain and simple. If that option is used just makes the system extremely dangerous. We are talking major property damage, fire, and death dangerous. Most Jurisdictions arre aware of the Danger and have amended 690.47 out of local codes because they know it is dangerous.

              That is why I was surprised, especially a city the size of San Diego left it in.

              But yeah I remember the two rules well. I have gone to battle twice. won one war, lost another. The one that I won was in King of Prussia Pennsylvania on a large data center we built. The Inspector wanted a Emergency Power Disconnect Button at every egress point. We call those disgruntled Installer Button. So as you walk out the door, hit the button and the room goes ark and quite along with knocking out all communications in a city. Anyway there are some leniencies in the code that allow you not to use Emergency Disconnect. That little button he wanted was a $3 million dollar button.

              MSEE, PE

              Comment


              • #22
                Originally posted by Sunking View Post

                690.47(D) is the only code written known to be dangerous to public safety. That is what happens when you let advocates get involved with something. In thi scase John Wiles from NMSU and Sandia National Labs. John pretty much srote 690. Anyway 690.47(D) intention is to save the homeowner significant installation cost. That is it plain and simple. If that option is used just makes the system extremely dangerous. We are talking major property damage, fire, and death dangerous. Most Jurisdictions arre aware of the Danger and have amended 690.47 out of local codes because they know it is dangerous.

                That is why I was surprised, especially a city the size of San Diego left it in.
                Exception 2 can be interpreted in a way that means an additional electrode is not required for rooftop systems. That significantly reduces the number of systems subject to the unsafe rule, and for ground and pole mounts that remain, there are other ways to deal with it. Perhaps that is why the CEC left that code section alone, but I don't know. I've also seen some city inspection guidelines (not San Diego) state that if an auxiliary electrode is provided to ground the array, it *must* be bonded to the service electrode, without bothering to actually write or amend any codes to support it. At some level, since the AHJ is always right, the inspection checklists are as powerful as code.

                2017 NEC helped, by no longer *requiring* that auxiliary electrode for any system, but it still allows it, and still allows it to be unbonded to the GES (except through the EGC). So, for someone who really wants to create the hazard of potential between two otherwise unbonded electrodes that will drive current through the EGC, they are allowed to do it.

                Again, tying this back to the OP's question, neither the NEC, the CEC, nor Walnut Creek's city code prescribe lightning protection for PV systems, just ground fault protection. If the OP is concerned about lightning, it is probably an add-on to the existing contract, or at the very least, is a consideration to be weighed against the aesthetic desire for interior conduit runs.
                Last edited by sensij; 08-10-2017, 02:03 PM.
                CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

                Comment


                • #23
                  Originally posted by sensij View Post

                  Exception 2 can be interpreted in a way that means an additional electrode is not required for rooftop systems. That significantly reduces the number of systems subject to the unsafe rule, and for ground and pole mounts that remain, there are other ways to deal with it. Perhaps that is why the CEC left that code section alone, but I don't know. I've also seen some city inspection guidelines (not San Diego) state that if an auxiliary electrode is provided to ground the array, it *must* be bonded to the service electrode, without bothering to actually write or amend any codes to support it. At some level, since the AHJ is always right, the inspection checklists are as powerful as code.

                  2017 NEC helped, by no longer *requiring* that auxiliary electrode for any system, but it still allows it, and still allows it to be unbonded to the GES. So, for someone who really wants to create the hazard of potential between two otherwise unbonded electrodes that will drive current through the EGC, they are allowed to do it.

                  Again, tying this back to the OP's question, neither the NEC, the CEC, nor Walnut Creek's city code prescribe lightning protection for PV systems, just ground fault protection. If the OP is concerned about lightning, it is probably an add-on to the existing contract, or at the very least, is a consideration to be weighed against the aesthetic desire for interior conduit runs.
                  A better way to help reduce lightning damage is to install a high pole or tower with a rod or Linear Dissipater Array connected to a down wire to direct a strike away from your roof. It creates a "cone" protection roughly having a diameter on the ground about the height of the pole. This type is used at POCO switch-yards and can cover a much bigger area then just putting individual rods along the roof ridge or edge.

                  Of course a HOA might not like a tall pole.

                  Comment


                  • #24
                    Originally posted by sensij View Post
                    I've also seen some city inspection guidelines (not San Diego) state that if an auxiliary electrode is provided to ground the array, it *must* be bonded to the service electrode, without bothering to actually write or amend any codes to support it. At some level, since the AHJ is always right, the inspection checklists are as powerful as code.
                    That is the way it should be done.

                    Originally posted by sensij View Post
                    Again, tying this back to the OP's question, neither the NEC, the CEC, nor Walnut Creek's city code prescribe lightning protection for PV systems, just ground fault protection. If the OP is concerned about lightning, it is probably an add-on to the existing contract, or at the very least, is a consideration to be weighed against the aesthetic desire for interior conduit runs.
                    Np problem there, no LPS is required or needed. If you properly bond the frames, and take a down conductor to the building Ground Electrode System, is as good as it gets. Adding LPS does not gain you anything as the are almost the exact same thing without Air Terminals. You want an Air Terminal. put it on a Solar Panel Frame along with a Bulls Eye.

                    If it were me and I was really concerned about lightning, bond it to code and buy the best TVSS/SPD money can buy to put on the roof and at the AC Service Meter.
                    Last edited by Sunking; 08-10-2017, 02:00 PM.
                    MSEE, PE

                    Comment


                    • #25
                      I'm late to the party on this thread, but I am curious what the difference is between the SE7600-USS and the SE7600-USS2.

                      Comment


                      • #26
                        Originally posted by Relaxedchap View Post
                        I'm late to the party on this thread, but I am curious what the difference is between the SE7600-USS and the SE7600-USS2.
                        The latter is the StorEdge and capable of supporting a battery in bimodal mode.
                        OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

                        Comment

                        Working...
                        X