Max,
Is the Minerallac clamp really rated as a bonding device? I don’t think so. It may make an electrical connection, but I don’t think it is nearly as good as a ground bushing. It is also made of cad-plated steel and I don’t think it is as durable as EMT or a ground bushing with a cad plated fastener. It probably doesn’t matter too much if it is just protecting conductors and a bonding conductor between two rails, but I would not want to rely on this for any circuits containing the final equipment grounding conductor or main circuit conductors. Not something I would lose a whole lot of sleep over—there are far bigger issues to solve. Of far more significance is the overall wire management of USE-2 conductors in the array. Structure suppliers still do a terrible job of providing an effective means of controlling and protecting conductors—this is nearly a decade after the first commercially available system was developed. Is anyone else ticked off about this??? Bill. From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Max Balchowsky Sent: Wednesday, October 14, 2009 2:59 PM To: RE-wrenches Subject: Re: [RE-wrenches] Rooftop wiring methods between multiple subarrays Bill, as you know, if the array is on a tilted roof (tile track bkts or fast jacks) and the array is monolithic, all the wires go directly from under the panels to the junction box ( I mis-spoke when I said Combiner box, I too don't see the need for combiner boxes on residential systems ).We go directly from the weeb ground lug into the junction box then down. The panels are bonded to the rails with the Weeb Bonding Clips. If the array consists of tilted rows, we've used either a bare copper wire tie wrapped to the EMT between rows or run in the EMT (most rows are 18-24" apart depending on angle). What I've done on the last couple of tilted row residential jobs is used the mineralac clamps and EMT between rows (inspector has bought it as a "bond" between rows then used the ground lug on the last row to take the ground into the junction box and down.......... Max _____ From: Bill Brooks <billbroo...@yahoo.com> To: RE-wrenches <re-wrenches@lists.re-wrenches.org> Sent: Tuesday, October 13, 2009 7:59:13 AM Subject: Re: [RE-wrenches] Rooftop wiring methods between multiple subarrays Max, I’m not sure I understand your scenario completely. The WEEB-Lug, superior to the ILSCO product, is intended for grounding the rack to the equipment grounding conductor. Each rail gets a WEEB-Lug and an EGC ties all those rails together and takes the ground to the j-box to enter the conduit system (don’t like combiner boxes on residential rooftops). The key is how to effectively bond metal conduit. Bonding bushings or box fittings are the only means I know of to do this. As others have pointed out, the bushings currently on the market are often not designed for outdoor use. This is particularly of concern in high corrosion areas (where EMT is not recommended). My experience is that it is better to bond with indoor lugs than not to bond at all. When I check old lugs in the field with cad-plated set screws, they often still have a good bond even though the screw is fully rusted. The key is the bond between the conductor and the lug, and the between the lug and the metal it is attached to. If both surfaces are tight and no oxygen is getting to the interfaces, the bond will stay for a very long time—possibly the life of the system in a lower corrosion environment. The set screw is mechanical pressure, not the bonding point—rust locks it.. It is best to use outdoor-rated equipment, but in some cases, it may be impossible because the equipment may not be manufactured, since the market is too small. Oh the joys of exterior wiring. Bill.
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