Solar Guppy Discussion Forum :: Electrical grounding of Unirac SunFrame rails : All Things Hardware For Solar Installations

Their literature states: "Specialized teeth on the washer are constructed to embed into anodized aluminum and establish a gas-tight electrical connection." Breaking the anodized layer anyplace where is is not gas tight, will allow O2 to get in and corrode it. Self-taping threads into aluminum are fairly gas tight (if the pilot hole is not too big).

From your PDF, Apx G.
" The Belleville washer provides
uniform tension, and a torque screwdriver should be used for all electrical connections. See
Figure G-2. Some new grounding lugs have been listed for use without the anti-oxidant
compound since the design of the lug penetrates the oxidation. It is not acceptable to use the hexhead,
green grounding screws (even when they a have 10-32 threads) because they are not
suitable for outdoor exposure and will eventually corrode. The same can be said for other screws,
lugs, and terminals that are not suitable for outdoor applications."

What they did not cover was to skip abrading the aluminum frame, if you use the SPECIAL toothed washer, at the proper torque, as prescribed by the Mfg. A dab of anti-ox before the install won't hurt, but I doubt that stuff lingers long in the weather outdoors.

In the spacecraft industry, we use either gold plate over the aluminum housing, or something called "Chemfilm" which is a clear conductive coating over the entire part, applied somewhat the same way as anodizing. I suspect in the future, the official panel grounding point, will either have a clear chemfilm coat, copper/tin electroplate or gold flash, to insure a long lived, good contact.

I contend that using the WEEBLug http://www.we-llc.com/WEEBLug_story.html parts, or an equivalent, will give the best grounding, over 25 years, and certainly much better results after several years of weather, over a bolt/anti-ox/bare aluminum.

Or we may just continue to disagree. Aluminum holds up for about 5 years in my area (coastal Los Angeles) and then, generally turns to powder, unless it's been protected somehow. I've seen hollow I & L beams, where tooling has sat outdoors in a storage yard, and the anodized skin lasts, but the inner core rots out. Very light weight though!

Author:	rickeolis [ Thu Sep 25, 2008 5:13 pm GMT EthGMT ]
Post subject:	Re: Electrical grounding of Unirac SunFrame rails
Scott, This solution was purposed to me by an engineer at Unirac: Using the lugs designed for the SunFrame (identical stye as Weeb.) Drill a hole throuth the cross section of the rail that will pass through the cavity hole in the rail and then use a stainless nut and bolt to attach the lug. The lug has cutting nubs that penetrates the anodization and gives a solid mount. -Rick-

Author:	niel [ Thu Sep 25, 2008 7:29 pm GMT EthGMT ]
Post subject:	Re: Electrical grounding of Unirac SunFrame rails
rick, maybe scott knows what you're talking about, but i'm thinking some pics might be helpful in letting me visualize what that solution entails. edit to add that now i picture in my mind what they are proposing so nevermind the pics.

Author:	mike90045 [ Fri Sep 26, 2008 10:11 am GMT EthGMT ]
Post subject:	Re: Electrical grounding of Unirac SunFrame rails
Their literature states: "Specialized teeth on the washer are constructed to embed into anodized aluminum and establish a gas-tight electrical connection." Breaking the anodized layer anyplace where is is not gas tight, will allow O2 to get in and corrode it. Self-taping threads into aluminum are fairly gas tight (if the pilot hole is not too big). From your PDF, Apx G. " The Belleville washer provides uniform tension, and a torque screwdriver should be used for all electrical connections. See Figure G-2. Some new grounding lugs have been listed for use without the anti-oxidant compound since the design of the lug penetrates the oxidation. It is not acceptable to use the hexhead, green grounding screws (even when they a have 10-32 threads) because they are not suitable for outdoor exposure and will eventually corrode. The same can be said for other screws, lugs, and terminals that are not suitable for outdoor applications." What they did not cover was to skip abrading the aluminum frame, if you use the SPECIAL toothed washer, at the proper torque, as prescribed by the Mfg. A dab of anti-ox before the install won't hurt, but I doubt that stuff lingers long in the weather outdoors. In the spacecraft industry, we use either gold plate over the aluminum housing, or something called "Chemfilm" which is a clear conductive coating over the entire part, applied somewhat the same way as anodizing. I suspect in the future, the official panel grounding point, will either have a clear chemfilm coat, copper/tin electroplate or gold flash, to insure a long lived, good contact. I contend that using the WEEBLug http://www.we-llc.com/WEEBLug_story.html parts, or an equivalent, will give the best grounding, over 25 years, and certainly much better results after several years of weather, over a bolt/anti-ox/bare aluminum. Or we may just continue to disagree. Aluminum holds up for about 5 years in my area (coastal Los Angeles) and then, generally turns to powder, unless it's been protected somehow. I've seen hollow I & L beams, where tooling has sat outdoors in a storage yard, and the anodized skin lasts, but the inner core rots out. Very light weight though!

Author:	solartek [ Fri Sep 26, 2008 2:16 pm GMT EthGMT ]
Post subject:	Re: Electrical grounding of Unirac SunFrame rails
mike90045 wrote: Their literature states: "Specialized teeth on the washer are constructed to embed into anodized aluminum and establish a gas-tight electrical connection." Breaking the anodized layer anyplace where is is not gas tight, will allow O2 to get in and corrode it. Self-taping threads into aluminum are fairly gas tight (if the pilot hole is not too big). From your PDF, Apx G. " The Belleville washer provides uniform tension, and a torque screwdriver should be used for all electrical connections. See Figure G-2. Some new grounding lugs have been listed for use without the anti-oxidant compound since the design of the lug penetrates the oxidation. It is not acceptable to use the hexhead, green grounding screws (even when they a have 10-32 threads) because they are not suitable for outdoor exposure and will eventually corrode. The same can be said for other screws, lugs, and terminals that are not suitable for outdoor applications." What they did not cover was to skip abrading the aluminum frame, if you use the SPECIAL toothed washer, at the proper torque, as prescribed by the Mfg. A dab of anti-ox before the install won't hurt, but I doubt that stuff lingers long in the weather outdoors. In the spacecraft industry, we use either gold plate over the aluminum housing, or something called "Chemfilm" which is a clear conductive coating over the entire part, applied somewhat the same way as anodizing. I suspect in the future, the official panel grounding point, will either have a clear chemfilm coat, copper/tin electroplate or gold flash, to insure a long lived, good contact. I contend that using the WEEBLug http://www.we-llc.com/WEEBLug_story.html parts, or an equivalent, will give the best grounding, over 25 years, and certainly much better results after several years of weather, over a bolt/anti-ox/bare aluminum. Or we may just continue to disagree. Aluminum holds up for about 5 years in my area (coastal Los Angeles) and then, generally turns to powder, unless it's been protected somehow. I've seen hollow I & L beams, where tooling has sat outdoors in a storage yard, and the anodized skin lasts, but the inner core rots out. Very light weight though! I don't think we disagree as much as you think we do. I'm already employing the WeebLug product to ground the mounting rails on systems installed using Unirac's SolarMount rails. I don't do any removal of the anodization on these rails and rely on the puncturing of the anodization provided by the WeebLug. But for the panels themselves I do employ the method outlined in Appendix G. Quoting their recommended procedure for the panels more fully... "For those situations requiring an equipment-grounding conductor larger than 10 AWG, a stainless-steel #10 screw, nut, flat washers, Belleville spring and lock washers can be used to attach an ILSCO GBL4 DBT, Burndy CL50-DB-T, or equivalent lug to the module frame at the point marked for grounding. See Figure G-1. Before attaching the lug to the module, a stainless- steel brush should be used to remove any anodization or oxidation from the aluminum module frame, and a thin coat of anti-oxidant film should be placed on the clean aluminum surface. Burndy Penetrox A-13 or equivalent should be used. The flat washers are required to prevent the lock washers from digging into the soft copper or aluminum. The Belleville washer provides uniform tension, and a torque screwdriver should be used for all electrical connections. See Figure G-2. Some new grounding lugs have been listed for use without the anti-oxidant compound since the design of the lug penetrates the oxidation. It is not acceptable to use the hex- head, green grounding screws (even when they a have 10-32 threads) because they are not suitable for outdoor exposure and will eventually corrode. The same can be said for other screws, lugs, and terminals that are not suitable for outdoor applications." Now I have a system where I'm going to mount the panels using Unirac's SunFrame rails instead of Solarmount rails. And I want to electrically ground the rails. I would use the WeebLug if it was possible, but it is not readily compatible with the SunFrame. So my original question was how are other people grounding SunFrame rails. One possibility I suggested was applying the same method to the rails that I do to the panels. Another might be trying to use the WeebLug. In either case there is no good solution that doesn't involve drilling a hole in the SunFrame rail. And if you object to the method of grounding the rails I suggested, which is equivalent to the grounding method I'm using for the panels, then I guess you think that my method of grounding the panels is also suspect. Scott.

Author:	solartek [ Fri Sep 26, 2008 2:19 pm GMT EthGMT ]
Post subject:	Re: Electrical grounding of Unirac SunFrame rails
rickeolis wrote: Scott, This solution was purposed to me by an engineer at Unirac: Using the lugs designed for the SunFrame (identical stye as Weeb.) Drill a hole throuth the cross section of the rail that will pass through the cavity hole in the rail and then use a stainless nut and bolt to attach the lug. The lug has cutting nubs that penetrates the anodization and gives a solid mount. -Rick- Rick, When you say use the lugs designed for the SunFrame, I was not aware that there were grounding lugs available for the SunFrame rails that worked like the WeebLug does for the SolarMount rails. Or are you just suggesting I use the WeebLug via a hole drilled into the SunFrame rail below where the panels sit? Scott.

Solar Guppy Discussion Forum http://solar-guppy.com/forum/

Electrical grounding of Unirac SunFrame rails http://solar-guppy.com/forum/viewtopic.php?f=4&t=693	Page 2 of 2

Author:	rickeolis [ Mon Sep 29, 2008 4:51 pm GMT EthGMT ]
Post subject:	Re: Electrical grounding of Unirac SunFrame rails
Hi Scott, Yes, that's right, drill a hole just below the frame holder and put a S.S. nut and bolt there to hold the lug which will then penetrate the anodizing. Sorry I don't have pic's... -Rick-

Author:	niel [ Thu Oct 23, 2008 1:43 am GMT ErdGMT ]
Post subject:	Re: Electrical grounding of Unirac SunFrame rails
thanks for posting that. looks like tight clearance to fit the connector making the point of the drilling critical or you'd get a hole too big and if drilled too low it could weaken the rail.

Author:	mike90045 [ Thu Oct 23, 2008 10:07 am GMT ErdGMT ]
Post subject:	Re: Electrical grounding of Unirac SunFrame rails
Dang, that looks like it all mill finish aluminum. but worse, I don't see any fancy lug that digs into the aluminum, or is it hidden between the rail and ground adapter ? All I can see is a split ring lock washer, which can't be a good UL ground. Mike (coastal kalifornia fog belt where this stuff will be swiss cheese in 7 years) 90045

Author:	solartek [ Thu Oct 23, 2008 11:31 am GMT ErdGMT ]
Post subject:	Re: Electrical grounding of Unirac SunFrame rails
Mike, The rail is anodized aluminum. The WeebLug is tin-plated. You can just make out the thin sheet of material which has the raised holes to puncture the anodization and give a gas-tight contact between the lug and the rail. This is the standard WeebLug procedure just attached in a different place on the SunFrame rails as opposed to the SolarMount rails. Scott.

Page 2 of 2	All times are UTC - 5 hours [ DST ]
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group http://www.phpbb.com/