[RE-wrenches] definition of "areas of physical damage"

Ray ray at solarray.com
Mon Sep 18 09:50:20 PDT 2017 

That's one rule I don't fully understand.  As you mentioned, "subject to 
physical damage" is not well defined, and second Sch 40 PVC itself is 
tough.  I've purposely run over it with a. 3/4 ton truck, and it only 
ovals, it didn't break.  I've rarely seen broken PVC conduit, but what I 
have seen is broken couplings, male adapters, and especially LBs.  They 
are made from a more brittle plastic. I also see many failed glue jobs, 
too.

The other problem I find is not using expansion couplings for stub ups 
out of the ground.  The trench settles over the years, and pulls the 
conduit out of the MA, or breaks the MA.  Again, Schedule 80 doesn't 
solve that problem either.  I think better glue, stronger fittings, and 
expansion couplings are needed as well as Sch 80 to insure long term 
protection.

Ray Walters

Remote Solar


On 9/18/17 9:53 AM, cpickard aladdinsolar.com wrote:
>
> You should always specify Sched 80 for those stubs out of the ground. 
> Makes sense to me that an AHJ requires it -- protect the conductors 
> from maintenance tractor, lawn mower, weed whip, show shovel 
> (Minnesota), and temperature differentials (transitioning from 
> underground temps to air). But I haven't ever seen a formal definition 
> of "subject to physical damage" in the code. 230.5 describes a few 
> examples of physical damage areas for protection (although is 
> specifically talking about service entrance conductor locations) which 
> includes exactly your conductor locations. Also review Articles 300.4 
> and 300.5.
>
>> On September 13, 2017 at 3:02 PM Dana <dana at solarwork.com> wrote:
>>
>> Same rule enforced here in Idaho & Colorado. In Idaho we even have to 
>> use Sched 80 anywhere above the finished floor even the attic and in 
>> walls [if required].
>>
>> ----------------------------------------------------------------------------
>>
>> Dana Orzel                       Great Solar Works, Inc.
>>
>> *208.721.7003 dana at solarwork.com*
>>
>> Idaho Contractor - # 028765          Idaho PV # 028374
>>
>> NABCEP # 051112-136 www.solarwork.biz
>>
>> _"Responsible Technologies for Responsible People since 1988" _
>>
>> *P* Please consider the environment before printing this email.
>>
>> *From:* RE-wrenches 
>> [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On Behalf Of 
>> *Jerry Caldwell
>> *Sent:* Wednesday, September 13, 2017 11:03 AM
>> *To:* RE-wrenches <re-wrenches at lists.re-wrenches.org>
>> *Subject:* [RE-wrenches] definition of "areas of physical damage"
>>
>> Dear Wrenches,
>>
>> I have a residential ground mounted installation that did not pass 
>> inspection due to schedule 40 PVC conduit stubbing up from a trench 
>> to the inverters and subpanel.  The inverters and subpanel are hung 
>> on Unistrut, which is attached to the rear posts of the ground rack.  
>> There is a second subpanel next to the main on the side of the house 
>> with schedule 40 stubbing up into it as well.
>>
>> The inspector insists that conduit stubbing out of the ground is 
>> subject to physical damage and needs to be replaced with schedule 80 
>> even though it is not in an area where vehicles or mobile equipment 
>> are used.  Is there a generally accepted definition of "areas of 
>> physical damage" as seen in 350.10 (F)?
>>
>> The inspector has said he would consider my argument if I can provide 
>> language from the Code to back up my position.
>>
>> Any help is greatly appreciated.
>>
>> Jerry Caldwell
>>
>> On Saturday, October 4, 2008 8:28 AM, Geoff Greenfield 
>> <geoff at third-sun.com <mailto:geoff at third-sun.com>> wrote:
>>
>> thanks for input Bill, and also for tip on zipties. We have dealt 
>> with intermittent groundfaults caused by faulty xlp!  Had to spray 
>> water on array to "find" it.  PITA!  Almost makes me want to submerge 
>> the spool next time and do my own test.
>>
>> For a brighter energy future,
>>
>> Geoff Greenfield
>>
>> President
>>
>> Third Sun Solar & Wind Power Ltd.
>>
>> 340 West State Street, Unit 25
>>
>> Athens, OH 45701
>>
>> 740.597.3111   Fax 740.597.1548
>>
>> www.Third-Sun.com <http://www.Third-Sun.com>
>>
>> Clean Energy - Expertly Installed
>>
>> ----- Bill Brooks <billbrooks7 at yahoo.com 
>> <mailto:billbrooks7 at yahoo.com>> wrote:
>>
>> > Geoff,
>>
>> > 
>>
>> > SS zip ties are good, but you must be very careful not to pull them tight.
>>
>> > They should only be snug, not tight. These SS zip ties have been 
>> shown to
>>
>> > cause ground faults in many cases. Commercial rooftops are 
>> accessible, but
>>
>> > not readily accessible. Conductors must be supported properly and 
>> protected
>>
>> > from physical damage. The conductors must follow structural members. 
>> If they
>>
>> > leave structural members, they must be in a raceway of some kind. A 
>> variety
>>
>> > of options there.
>>
>> > 
>>
>> > Bill.
>>
>> > 
>>
>> > -----Original Message-----
>>
>> > From: re-wrenches-bounces at lists.re-wrenches.org 
>> <mailto:re-wrenches-bounces at lists.re-wrenches.org>
>>
>> > [mailto:re-wrenches-bounces at lists.re-wrenches.org 
>> <mailto:re-wrenches-bounces at lists.re-wrenches.org>] On Behalf Of Geoff
>>
>> > Greenfield
>>
>> > Sent: Friday, October 03, 2008 7:19 AM
>>
>> > To: RE-wrenches
>>
>> > Cc: Randy; Kent Phillips
>>
>> > Subject: [RE-wrenches] Protection of Conductors
>>
>> > 
>>
>> > Hey wrenchers... we have an internal debate going about a code section
>>
>> > interpretation... "subject to physical damage".  Code compliance is 
>> a must,
>>
>> > best practice is an expectation (...weighed against material and 
>> labor cost
>>
>> > (prevailing wage job)).
>>
>> > 
>>
>> > Application is a flat roof with no public access (locked hatch).  We are
>>
>> > using DP+W "Power-tube" flat roofing system for the first time... the
>>
>> > question is how to deal with the inter-row N-S wire runs... about 
>> 100 gaps
>>
>> > about 24" between the E-W rows of panels. There are plenty of 2"x2" 
>> strut
>>
>> > members running under the array N-S. We will "exit" the array field in
>>
>> > ridgid conduit to combiner boxes.
>>
>> > 
>>
>> > The flat roof system we usually use has built in wire trays... using 
>> this
>>
>> > new system has brought up this question... Our options include 
>> dressing the
>>
>> > XLP bundles with SS zip ties alongside the N-S struts, or using 
>> Galv. RMC,
>>
>> > strapped, with bushings (or S-80 PVC) at all these walkways... or using
>>
>> > Unistrut (w/cap) as a lay in wireway (to speed up labor (debatable)).
>>
>> > 
>>
>> > Below are some of the code references... the basic question seems to be:
>>
>> > does the limited access of this roof keep us out of "subject to physical
>>
>> > damage"?  What is a "Readily accessible location?"
>>
>> > 
>>
>> > Thanks everyone.
>>
>> > 
>>
>> > For a brighter energy future,
>>
>> > 
>>
>> > Geoff Greenfield
>>
>> > President
>>
>> > Third Sun Solar & Wind Power Ltd.
>>
>> > 340 West State Street, Unit 25
>>
>> > Athens, OH 45701
>>
>> > 
>>
>> > 740.597.3111    Fax 740.597.1548
>>
>> > www.Third-Sun.com <http://www.Third-Sun.com>
>>
>> > 
>>
>> > Clean Energy - Expertly Installed
>>
>> > 
>>
>> > 
>>
>> > >
>>
>> > > Next, one might argue, I suppose, that the racking system itself, acts
>>
>> > > as
>>
>> > > protection and that the conductors should therefore, not be considered
>>
>> > > to
>>
>> > > be exposed.  I disagree based on NEC definition.  That stated, I
>>
>> > > would
>>
>> > > consider these NEC references for more perspective:
>>
>> > >
>>
>> > > Pretty straightforward NEC 100 Definitions Exposed (as applied to
>>
>> > > wiring
>>
>> > > methods):  On or attached to the surface...
>>
>> > >
>>
>> > > NEC 300.4 gives various cases for protection against physical damage
>>
>> > > requirements.  Long article.  Worth a read.  Does not address our
>>
>> > > exact
>>
>> > > case, but I would say that the following methods would be appropriate
>>
>> > > based on similar cases...
>>
>> > >
>>
>> > > NEC 344.10 (A)(1) Galvanized steel and stainless steel RMC.  ...shall
>>
>> > > be
>>
>> > > permitted under all atmospheric conditions and occupancies.
>>
>> > >
>>
>> > > NEC 352.10(f) Exposed. PVC conduit shall be permitted for exposed
>>
>> > > work.
>>
>> > > PVC conduit used exposed in areas of physical damage shall be
>>
>> > > identified
>>
>> > > for the use.  FPN:  PVC conduit, Type Schedule 80, is identified for
>>
>> > > areas
>>
>> > > of physical damage.
>>
>> > >
>>
>> > > Also,
>>
>> > >
>>
>> > > NEC 690.31(A) ...Where photovoltaic source and output circuits
>>
>> > > operating
>>
>> > > at maximum system voltages greater than 30 volts are installed in
>>
>> > > readily
>>
>> > > accesible locations, circuit conductors shall be installed in a
>>
>> > > raceway.
>>
>> > >
>>
>> > > One might argue, then, why don't the module interconnects have to be
>>
>> > > protected, also...
>>
>> > >
>>
>> > > NEC 690.31(B) is really the key to all of this:  Single-Conductor
>>
>> > > Cable.
>>
>> > > Single-conductor cable type USE-2, and single-conductor cable listed
>>
>> > > and
>>
>> > > labeled as photovoltaic (PV) wire shall be permitted in exposed
>>
>> > > outdoor
>>
>> > > locations in photovoltaic source circuits FOR PHOTOVOLTAIC MODULE
>>
>> > > INTERCONNECTIONS within the photovoltaic array.
>>
>> > >
>>
>> > > So, I suppose that if our source circuit interconnections extend from
>>
>> > > row
>>
>> > > to row, then we can leave those exposed. I don't like it, but it
>>
>> > > would
>>
>> > > probably have to be accepted.
>>
>> > >
>>
>> > >
>>
>> > _______________________________________________
>>
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>>
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>>
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>
> Charlie Pickard
>
> NABCEP Certified PV Installer
>
> 952-567-4479 (cell)
>
> 952-401-7073 (office)
>
> cpickard at AladdinSolar.com <mailto:cpickard at AladdinSolar.com>
>
>
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