1/4" x 20 is no more the 10 ftlbs (120 inlbs) and a good 1/4" impact should be able to get you over 30 ftlb. When you overtorq bolts and nuts you put undue and irreversible stretching and or tearing of the material not to mention warping or bending of the plates, and rails, loosening and retorqing is a wait as if damage is done its done, the best solution is to replace all the stressed hardware. I have seen unirac "T" bolts crack the the rails with a bad result, so the question is how far do you want to dig and risk to take. Regarding cracked glass, I have only seen this with incorrect use of the clamps but over torqing will also crush the frames. I have inspected arrays after high wind events that resulted in destruction of the array and the manufacture in all cases used over torq as thier out so warranty are only as good as the installers. Jerry NABCEP PV inspector
On Sun, Sep 5, 2021, 8:56 PM Corey Shalanski <coreso...@gmail.com> wrote: > August, > > Thanks for your feedback.The racking model is EcoFoot2+ > <https://ecolibriumsolar.com/ecofoot2plus/> by Ecolibrium Solar (now part > of Unirac). These module clamps are also self-grounding with teeth to bite > into the module frame. I reached out to the manufacturer, who confirmed > that the clamp material is aluminum extrusion and the hardware is stainless > steel. > > The modules were installed about 2 weeks ago, so not very much time has > elapsed to be able to observe potential resultant damage. We haven't seen > any problems so far. > > -- > Corey > > > On Fri, Sep 3, 2021 at 6:35 AM August Goers <aug...@luminalt.com> wrote: > >> >> Hi Corey - >> >> For many years we used Pro Solar racking and Unirac Solarmount and >> tightened the clamps with impact drivers. At some point maybe roughly 8 >> years ago, Unirac switched its mid clamps to stainless steel self grounding >> clamps with teeth to bite into the module frame. We continued to use >> impacts with no issue. Then, starting around 4 years ago, we started to >> have module glass failures with our SunPower commercial systems and these >> Unirac clamps. We immediately switched to torque wrenches for tightening >> the clamps. However, the failures continued. My guess is that the poor >> design of the Unirac mid clamps in conjunction with thinner “weaker” module >> frames exasperated the issue. We now have stopped using those mid clamps >> and continue to hand tighten all clamps. We primarily install SunPower, and >> their residential module frames have a lip so all the pressure from the >> clamp doesn’t go to the glass. >> >> Getting to your question - what kind of mid clamps do you have? If they >> are aluminum, there may be less risk than the stainless clamps. I would be >> worried that the process of loosening and then re-tightening might cause >> more damage than good if there aren’t any problems that have occurred to >> date. It’s a good question. >> >> August >> Luminalt >> > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org > >
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