Racking span question

[Dsspro]

I committed to 72 cell CSun 310 panels tonight, when pulling up the Unirack span design tool it wants my span at 45" or less. It's 3" short of how I planned on mounting. Any concern mounting at 48" or do I need to look at another option?

The Ironridge design tool didn't support this size panel.

[Dsspro]

FYI it's on an accessory garage in MN with a 5/12 roof.

[sensij]

You could try using the Iron Ridge tool with a panel like CS6U-320P, which is about the same size and weight. It suggests 4 ft spans are ok with the XR100 rail. Note that integrated grounding is not compatible with the CSUN panels, so you'll need to bond each panel to the EGC with a listed lug.

[J.P.M.]

I committed to 72 cell CSun 310 panels tonight, when pulling up the Unirack span design tool it wants my span at 45" or less. It's 3" short of how I planned on mounting. Any concern mounting at 48" or do I need to look at another option?

The Ironridge design tool didn't support this size panel.

I'd call Unirack and ask them. I'd also get any affirmative answer they may give you in writing. Or, change the design to reflect a 45" span or less. Or, recalc. it, (or have a qualified person do the recalc), and see if a 48" span can be made to work.

If I was asked, without a lot more of particulars about the design, and then some calcs., even if I was still working, I'd be unable to offer an opinion. I do know some other folks who would probably say "screw it, I'll chew into the factors or safety a bit", but I don't think too many P.E.s would offer such an opinion for free. If nothing else, doing so would perhaps open them up for liability problems. On a venue such as this one where the details are unknown, lots to lose. Nothing to gain.

[ButchDeal]

You could try using the Iron Ridge tool with a panel like CS6U-320P, which is about the same size and weight. It suggests 4 ft spans are ok with the XR100 rail. Note that integrated grounding is not compatible with the CSUN panels, so you'll need to bond each panel to the EGC with a listed lug.

And if the xr100 will not do the span then the xr1000 certainly will.

[emartin00]

I've noticed the same thing. I think there is something wrong with the Unirac tool. There is no reason their rail shouldn't hold up to 48" spans.
While playing around with the tool, I've had it tell me I can have a longer span with the mini rail than the standard rail.

[J.P.M.]

I've noticed the same thing. I think there is something wrong with the Unirac tool. There is no reason their rail shouldn't hold up to 48" spans.
While playing around with the tool, I've had it tell me I can have a longer span with the mini rail than the standard rail.

As I suggested, I'd call Unirac and ask them. Maybe there's a reason, maybe not. If an error, they'll be happy to hear about it.

[Dsspro]

So I had one of the engineeers at Renvu quote my system and figure out the equipment list.

He used the tool and came up with the SM rail working. He said something about the smaller rail being closed to the roof and able to support more weight and longer spans... said it didn't make sense logically but according to Unirack multiple times this was the case.

The IronRidge site doesn't support the panels as the UFO doesn't support 50mm sizes and to call them, if I use Renvus tool the xr100 works and they show different clamps that work for the 50mm panels.

[Dsspro]

I'd call Unirack and ask them. I'd also get any affirmative answer they may give you in writing. Or, change the design to reflect a 45" span or less. Or, recalc. it, (or have a qualified person do the recalc), and see if a 48" span can be made to work.

If I was asked, without a lot more of particulars about the design, and then some calcs., even if I was still working, I'd be unable to offer an opinion. I do know some other folks who would probably say "screw it, I'll chew into the factors or safety a bit", but I don't think too many P.E.s would offer such an opinion for free. If nothing else, doing so would perhaps open them up for liability problems. On a venue such as this one where the details are unknown, lots to lose. Nothing to gain.

Thanks my friend, I'll call them Monday.

[Dsspro]

You could try using the Iron Ridge tool with a panel like CS6U-320P, which is about the same size and weight. It suggests 4 ft spans are ok with the XR100 rail. Note that integrated grounding is not compatible with the CSUN panels, so you'll need to bond each panel to the EGC with a listed lug.

Do you know why it doesn't support intergrated grounding? I guess it's not the end of the world just slows it down a bit.

[J.P.M.]

Thanks my friend, I'll call them Monday.

You're most welcome. Got nothin' to lose by a phone call. Just sayin'.

[sensij]

Do you know why it doesn't support intergrated grounding? I guess it's not the end of the world just slows it down a bit.

Check out page 9 of the installation manual:

http://files.ironridge.com/pitched-roof-mounting/resources/brochures/IronRidge_Flush_Mount_Installation_Manual.pdf

UL 2703 for integrated ground is good for only the specific panels (or families of panels) that have been tested with the rack. Ironridge is actively adding to the list, and if you email them, they might be able to tell if the specific panel you are interested in is in queue.

[tyab]

About the IronRidge UFO - it does not support the 50mm panels so you have to use the slightly older end/mid clamps which do support the 50mm panels - look on the Iron Ridge site for the cut sheets which will give you the part numbers for the ones that support 50mm panels. If the grounding mid clamp approved list of modules does not list your panel - you have two choices. Use it and have a remote possibility that the AHJ will want to see the listing for that particular panel and then you are hosed - or use the older mid clamp that uses the WEEB washer. The WEEB washer setup is a generic panel approvable so a long as the panel has an anodized aluminum frame its is listed. Be aware that for older mid clamp that uses the WEEB washer - that WEEB washer is a single use only so get extras just in case you have move panels after torquing them down.