Grounded for two weeks...hopefully longer [RE-wrenches]

[Matt Lafferty]

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David H wrote:

>  We just had one of our installers get tagged by a county inspector 
>  with a new one. He stated that the code says "all grounding 
>  conductors smaller than #4 shall be in conduit". Therefore he wants 
>  all the the #10 bare copper connecting the modules placed in conduit. 
>  Does anyone have a rebuttal for us?

David / Wrenches:

Yep!  Rebuttal as follows:  "Here, have a nice jelly doughnut and chill
out!"  (Substitute local bottle of wine for doughnut in Sonoma County!) If
the Inspector is on a diet or a teetotaller, I would send him/her on the "go
look at pool pump equipment then come back to me and we'll talk" chase!

Technically, he may be right, depending on the actual installation (Roof vs.
Ground-Mount for instance).  I must say that I am quite surprised that it
doesn't / hasn't come up more often.  This was a problem locally for awhile
back in 1999/2000.  (FYI / Warning -There are additional, potentially
"unfriendly" relationships in this "Code vs. Application" issue if it's not
handled with care!!!!)  

For Roof-Top applications, the following may help. (Others may have found
another workaround... I hope they share, if so!)

The general underlying principle is "protection from physical damage"....
Something we should all consider in every install we do, regardless of
permits and inspections!

After numerous pleas for common sense and more than a few "training sessions
with doughnuts included", we came to the "generally mutual" consensus that,
for the purposes of grounding electrode conductors used for the purposes of
equipment grounding, "on the roof" would not invoke the "protection from
physical damage" clause.  (This does not allow USE-2 or any other
current-carrying circuit conductors laying across a roof!)  We always did
and always supported routing the grounding conductor "to and across the
roof" in conduit.... Generally with the other circuit conductors.

If the installation is "at ground-level", then "protection from physical
damage" requirements are to be followed.  Common Sense (Less than common in
some places) and Consideration for "what's the right thing to do" should go
both ways!  We need to be responsible, too!

NEC direction (short version here) for this comes principally from 250.64
and 250.120 (Texts copied below for reference).  We'll assume we all know
that we are required to ground the modules and support structure!
"Protected from Physical Damage" is not clearly defined on a "broad basis"
anywhere I've ever found in the NEC, FYI.  Some references actually specify
"within 10' above grade"....  In the case of a roof-mounted array, the
"grade" is technically the roof surface.  Tread lightly!

250.64(B) tells us that conductors smaller than 6 AWG have to be in conduit.
Caution - Don't even read 250.64(C) if you care to keep your lunch in your
stomach!

250.120(C) supports the "#6 and smaller in conduit" and adds the "physical
damage" clause.  This is your "out", but only if you can help the inspector
see that "up here on the roof" isn't "subject to physical damage" under the
"spirit of the Code principle".

I'll keep it at that.  I would surely love to hear from somebody who has
found a "friendlier & absolute work-around" on this for my own knowledge.
The "Protection from Physical Damage" definition especially!  A lot of what
and how we do things on the roof is subject to this clause, even if we
haven't had to tackle it yet!

Peace, Sunshine, Palm Trees, & No Gambian Credit Cards!

Matt Lafferty
Universal Energies Institute
mlafferty at universalenergies.com
(916) 422-9772
(916) 628-7694 Cell
(916) 914-2247 Fax
www.universalenergies.com

2002 NEC - Copyright NFPA
250.64 Grounding Electrode Conductor Installation.
Grounding electrode conductors shall be installed as specified in 250.64(A)
through (F).
(A) Aluminum or Copper-Clad Aluminum Conductors. Bare aluminum or
copper-clad aluminum grounding conductors shall not be used where in direct
contact with masonry or the earth or where subject to corrosive conditions.
Where used outside, aluminum or copper-clad aluminum grounding conductors
shall not be terminated within 450 mm (18 in.) of the earth.
(B) Securing and Protection from Physical Damage. A grounding electrode
conductor or its enclosure shall be securely fastened to the surface on
which it is carried. A 4 AWG copper or aluminum or larger conductor shall be
protected if exposed to severe physical damage. A 6 AWG grounding conductor
that is free from exposure to physical damage shall be permitted to be run
along the surface of the building construction without metal covering or
protection where it is securely fastened to the construction; otherwise, it
shall be in rigid metal conduit, intermediate metal conduit, rigid
nonmetallic conduit, electrical metallic tubing, or cable armor. Grounding
conductors smaller than 6 AWG shall be in rigid metal conduit, intermediate
metal conduit, rigid nonmetallic conduit, electrical metallic tubing, or
cable armor.
(C) Continuous. The grounding electrode conductor shall be installed in one
continuous length without a splice or joint, unless spliced only by
irreversible compression-type connectors listed for the purpose or by the
exothermic welding process.
Exception: Sections of busbars shall be permitted to be connected together
to form a grounding electrode conductor.
(D) Grounding Electrode Conductor Taps. Where a service consists of more
than a single enclosure as permitted in 230.40, Exception No. 2, it shall be
permitted to connect taps to the grounding electrode conductor. Each such
tap conductor shall extend to the inside of each such enclosure. The
grounding electrode conductor shall be sized in accordance with 250.66, but
the tap conductors shall be permitted to be sized in accordance with the
grounding electrode conductors specified in 250.66 for the largest conductor
serving the respective enclosures. The tap conductors shall be connected to
the grounding electrode conductor in such a manner that the grounding
electrode conductor remains without a splice.
(E) Enclosures for Grounding Electrode Conductors. Metal enclosures for
grounding electrode conductors shall be electrically continuous from the
point of attachment to cabinets or equipment to the grounding electrode and
shall be securely fastened to the ground clamp or fitting. Metal enclosures
that are not physically continuous from cabinet or equipment to the
grounding electrode shall be made electrically continuous by bonding each
end to the grounding electrode conductor. Where a raceway is used as
protection for a grounding electrode conductor, the installation shall
comply with the requirements of the appropriate raceway article.
(F) To Electrode(s). A grounding electrode conductor shall be permitted to
be run to any convenient grounding electrode available in the grounding
electrode system or to one or more grounding electrode(s) individually. The
grounding electrode conductor shall be sized for the largest grounding
electrode conductor required among all the electrodes connected to it.

250.120 Equipment Grounding Conductor Installation.
An equipment grounding conductor shall be installed in accordance with
250.120(A), (B), and (C).
(A) Raceway, Cable Trays, Cable Armor, Cablebus, or Cable Sheaths. Where it
consists of a raceway, cable tray, cable armor, cablebus framework, or cable
sheath or where it is a wire within a raceway or cable, it shall be
installed in accordance with the applicable provisions in this Code using
fittings for joints and terminations approved for use with the type raceway
or cable used. All connections, joints, and fittings shall be made tight
using suitable tools.
(B) Aluminum and Copper-Clad Aluminum Conductors. Equipment grounding
conductors of bare or insulated aluminum or copper-clad aluminum shall be
permitted. Bare conductors shall not come in direct contact with masonry or
the earth or where subject to corrosive conditions. Aluminum or copper-clad
aluminum conductors shall not be terminated within 450 mm (18 in.) of the
earth.
(C) Equipment Grounding Conductors Smaller Than 6 AWG. Equipment grounding
conductors smaller than 6 AWG shall be protected from physical damage by a
raceway or cable armor except where run in hollow spaces of walls or
partitions, where not subject to physical damage, or where protected from
physical damage.

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