[RE-wrenches] Megometers

Nick Soleil nicksoleilsolar at yahoo.com
Tue Nov 24 20:06:42 PST 2009


Hello Wrenches:
    I have read a few of the archives on this subject, and have a couple questions.  I have been testing arrays with an insulation tester, and have found that some module types have more leakage than other modules.  Bill mentioned Amorphous being really bad.  
    I have found my less expensive tester to work for me, but read in another post about the value of a .001 M ohm tester.  Is that level of accuracy need?  
    I was testing a Sanyo array today, and was told that ~20M ohms on the series string to ground was not a problem.  With the strings isolated, the array conductors commonly have voltage readings of 260V+ to ground, but it dissipates with the meter connected.  Is this induced voltage caused by the leakage current that the manufacturer called 'normal?'

 Nick Soleil
Project Manager
Advanced Alternative Energy Solutions, LLC
PO Box 657
Petaluma, CA 94953
Cell:   707-321-2937
Office: 707-789-9537
Fax:    707-769-9037




________________________________
From: Hans Frederickson <hans at fredelectric.com>
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Sent: Tue, November 24, 2009 4:32:11 PM
Subject: Re: [RE-wrenches] wiring the Soladeck

The "2-hole strain relief" is called a cable gland. T&B makes a line that
includes 2-hole, 3-hole, 4-hole etc. The part numbers all begin with
CC-NPT-*. The 2-hole gland is CC-NPT-12-G-2. You can find the complete
selection on the last page of this PDF:
http://tnblnx3.tnb.com/emAlbum/albums//tc_us/tc_1_ltnonmettalicflex.pdf

Be aware the diameter of the wires (USE or PV-wire) that you're running
through the gland and make sure you order a part that has the right size
holes. I like to run my #6 copper EGC through a gland or cord grip as well.
The T&B cable glands are not UV resistant, so you don't want to use them
where exposed to sunlight (i.e. keep the Soladeck under the array). I've got
a collection of UV-resistant cable glands but I can't remember the
manufacturer. The problem with those is that they aren't UL listed. If it's
not one problem, it's another...

The manufacturer of the Soladeck is RSTC Enterprises:
http://www.rstcenterprises.com/pdf/soladeck_brochure.pdf

I spoke with them a while back when I was getting sorted out with cable
glands and the guy I talked to claimed he was working on getting a line of
cable glands to sell with the Soladeck. I haven't seen this from any of the
suppliers however.

Regards,
-Hans


________________________________

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Mick Abraham
Sent: Tuesday, November 24, 2009 2:43 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] wiring the Soladeck


I drill where the "dimples" are in the sheet metal, then punch for .5" trade
size, then install one of the plastic two hole strain relief clamps as are
available from AEEsolar and others.

I feel that one must not rely on the foam lid gasket to sufficiently "clamp"
the power leads. That just seems like asking Murphy to impose the Law.

The conductor for grounding the metal array parts can just exit through a
drilled hole in the box with no strain clamp, because there's a metal loop
that this wire can first loop through to give some tug prevention.

Jolliness,

Mick Abraham, Proprietor
www.abrahamsolar.com

Voice: 970-731-4675



On Tue, Nov 24, 2009 at 3:12 PM, Dave Click <daveclick at fsec.ucf.edu> wrote:


    Wrenches-
    
    How are folks wiring the Soladeck boxes? It seems that the intent is
to use cord grips in the south end of the box, but I just saw another
installation where the wires just came directly in through the space at the
south end. Seems like the foam is included to keep bugs out rather than
provide strain relief to those incoming conductors, so I guess I'm just
looking for a reality check here.
    
    Thanks and happy Thanksgiving!
    DKC
    _______________________________________________
    


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