[RE-wrenches] SS zip ties

[Jeff Clearwater, Village Power Design]

Hi Bill and all,

I've been searching for an alternative to plastic wire ties for some 
time as I'm not sure they are going to hold up over the system life 
of 20-30+ years and it'll be an ugly site to have all those wires 
drop onto the roof.

But for a flush rooftop array, an assumption to replace broken ones 
with an O&M plan as Bill suggests is prohibitive unless you want to 
pull modules and rewire all over again.  Way too much labor.

At first I was glad to see the SS ties too - but they just don't work 
that well and I too worry about the sharp edges with all the 
contraction and expansion that goes on in an aluminum based racking 
system.

On many commercial jobs we've used our own home made wire loom by 
splitting liquidtight non-metallic on a table saw.  We then use a 
self tapper and washer to screw through the back of the inside of the 
split LT to the array frame and then use one-hole straps to hold the 
wire from coming out of the slot where we want to.  I shared this 
method way back on this list and at 
http://www.home.earthlink.net/~clrwater  It's code since it's outdoor 
rated wire anyway.

I sometimes even run the LT home to a LT fitting after stopping the 
split (after providing a drain loop/low spot).  Not exactly covered 
by the code but I see no inherent violation.

I'm glad to see UniRac coming out with a zip bundle that slides into 
their rail slot  but that does only some of the job as there are many 
places we need to attach that are not directly along their rails.

I've told the folks at UniRac, DP&W, ProSolar, AEE etc. that the 
first racking company that comes out with an integrated loom or wire 
handling system will rule.  That was 2 years ago.

Still waiting!

Thanks,

Jeff Clearwater
NorthEast Solar/Village Power Design




>Folks,
>
>I'm a bit sour on SS ties. These are easy to overtighten and have caused
>numerous ground faults in the field. My recommendation is to use
>UV-resistant black wire ties and install 2-3 times as many as necessary.
>Sure some will fail over time, but we are much less likely to have ground
>faults, and proper O&M says that we maintain the wire supports over time and
>replace broken ties as need. Proper tension is a must and people have to be
>shown how to do it properly and checked up on in the field to make sure they
>are not getting them too tight.
>
>Bill.
>
>-----Original Message-----
>From: re-wrenches-bounces at lists.re-wrenches.org
>[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of William
>Miller
>Sent: Wednesday, December 10, 2008 9:52 PM
>To: RE-wrenches
>Subject: Re: [RE-wrenches] SS zip ties
>
>Kent:
>
>To tighten:  1. Pull tie snug by hand.  2. Cut tail about 20 mm from
>clasp.  3. Roll tail with needle-nose pliers, like a sardine can lid.  This
>tightens tie and hides sharp end.
>
>See
>http://mpandc.com/practices/Technical_Procedures/PV_wiring/PV_wiring.html
>for photos.
>
>Do not over-tighten to avoid wire damage.
>
>William
>
>
>At 09:25 PM 12/10/2008, you wrote:
>>Fastenal has stainless ties is various lengths
>>
>>http://www.fastenal.com/web/products/detail.ex?sku=0710242
>>
>>For those that haven't used these before, beware that it is difficult to
>>tighten them.
>>
>>Kent Osterberg
>>Blue Mountain Solar
>
>
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-- 
~~~~~~~~~~~~~
Jeff Clearwater
Senior Design Engineer
NABCEP (tm) Certified Solar PV Installer
http://www.nabcep.org/
Village Power Design/NorthEast Solar Design
Turnkey Solar Design & Installation for the Commercial Sector
http://www.villagepower.com
gosolar at villagepower.com

Voice: 413-259-3750
Fax: 413-825-0703
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Amherst, MA 01002
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