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-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@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
goso...@villagepower.com
Voice: 413-259-3750
Fax: 413-825-0703
65 Schoolhouse Rd
Amherst, MA 01002
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