"I've also wondered if we should be fusing these things. One hand says definitely yes, on the other hand, a big lightning strike would trip the fuse, before the Delta could do its job."
I think a big lightning strike would jump the fuse like it wasn't there. So the fuse would really make no difference at all. Midnite has an arrestor coming that looks like it has some good possibilities and a UL listing! It also has a light system to show if it has been activated. I also have seen lightning damage and the delta seemed unharmed each time. We need to keep in mind that there is some luck involved; NOTHING is going to stop a lightning bolt that just traveled 10 or 20 miles across the sky, so it jumping a meter socket or fuse / breaker would not be hard to understand. Later, Bob From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of R Ray Walters Sent: Thursday, September 02, 2010 3:42 PM To: RE-wrenches Subject: Re: [RE-wrenches] Delta LA's I know, as Bill pointed out, that the Deltas are supposed to be mounted on the exterior to allow the damage to stay outside of the combiner box. But I've also seen a lot of old Deltas damaged by the sun, and seen them cracked off at the 1/2" nipple attachment point, which then leaves exposed THHN conductors against the edge of the knock out. Just bumping one with your foot or shoulder could crack the plastic. We just finished a project with BOS combiners, and I mounted the Deltas to the backing plate inside using a 2" PVC conduit clamp. In this case, the AHJs were very concerned with sealing all KOs on the sides of jboxes, so we would have had to mount the Deltas on Myer's Hubs. Clunky, and we didn't have 1/2" hubs. If conditions allow, I do prefer to hang them off the bottom of a box, as long as they're protected from physical abuse. Side mounting is definitely asking for trouble in many situations, they're just too easy to snap off. I've also wondered if we should be fusing these things. One hand says definitely yes, on the other hand, a big lightning strike would trip the fuse, before the Delta could do its job. BTW, with over 200 projects in lightning territory, I've never actually had a Delta blow itself while protecting the system. Plenty of lighting damage, though, with the Delta still just sitting there. Anyone using the DIN rail mountable equipment from Citadel? R. Walters r...@solarray.com Solar Engineer On Sep 1, 2010, at 6:32 PM, Dave Palumbo wrote: I am concerned with Delta LA 600VDC cans being mounted exterior from J-boxes (or disconnect switches) on ground mounts. I remember hearing from an old hand that these devices can fail in a manner that could possibly expose the wiring to human hands. The wires would have high voltage DC potential. Not something we need in our industry. Am I worrying about something that can't happen? Or should these be in PVC boxes? David Palumbo Independent Power LLC Offices in Lamoille and the Champlain Valley, Vermont 802.888.7194 www.independentpowerllc.com <http://www.independentpowerllc.com/> NABCEP Certified Solar PV InstallerT Vermont RE Incentive Program Partner From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of North Texas Renewable Energy Inc Sent: Tuesday, August 31, 2010 10:07 PM To: RE-wrenches Subject: Re: [RE-wrenches] Testing LSAs For the first time since 2004 we got a residential PV red tag for non-listed surge supressors. I just took them off and replaced them after we got the green tag. Of course he also red-tagged the copper ground plate because it was not thick enough. Go figure.... Jim Duncan North Texas Renewable Energy -----Original Message----- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org]on Behalf Of Andrew Truitt Sent: Tuesday, August 31, 2010 8:09 PM To: RE-wrenches Subject: Re: [RE-wrenches] Testing LSAs Question: Since the Delta lightning arrestors are not UL Listed, do they threaten the UL compliance of the PV system as a whole? - Andrew Truitt Currently of Standard Solar Free agent in the Denver area as of 10/6/10 On Tue, Aug 24, 2010 at 6:02 PM, Peter Parrish <peter.parr...@calsolareng.com> wrote: I would think that an ohmmeter set to the 10 Mega-ohm setting (or the highest setting possible), would be the first test. I would like to see something on the order of 750 k-ohms (3/4 of a mega-ohm). But the system should be tested at a higher voltage, than that available from a DMM. Apply 240 Vac and measure the RMS current. It should be should be 0.3 mA or less. Finally, these puppies really need to be tested at much higher voltages, perhaps someone knows how to use that megohmmeter to test? What does the manu recommend, "if suspect, throw it away and buy a new one"? - Peter Peter T. Parrish, Ph.D., President California Solar Engineering, Inc. 820 Cynthia Ave., Los Angeles, CA 90065 CA Lic. 854779, NABCEP Cert. 031806-26 peter.parr...@calsolareng.com Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885 ________________________________________ From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Kristopher Schmid Sent: Tuesday, August 24, 2010 1:30 PM To: 'RE-wrenches' Subject: [RE-wrenches] Testing LSAs What is the best method for testing the integrity of a DC and/or AC lightning surge arrestor? Specifically, i use the Delta LA units. I know they should be replaced if they look Bar-B-Qued, but otherwise...? Thanks, Kris Schmid Legacy Solar 864 Clam Falls Trail Frederic, WI 54837 715-653-4295 sol...@legacysolar.com www.legacysolar.com <http://www.legacysolar.com/> _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org <http://www.members.re-wrenches.org/> -- "Don't get me wrong: I love nuclear energy! It's just that I prefer fusion to fission. And it just so happens that there's an enormous fusion reactor safely banked a few million miles from us. It delivers more than we could ever use in just about 8 minutes. 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