In the nearly 30 years that I have been
dealing with the National Electrical Code, it never
ceases to amaze me how many new applications we as code
officials encounter that require us to apply the Code to installations not directly mentioned in the Code.
Many times we look at installations during inspections or plan
review and think, I know it’s wrong, but how do I back my
position with the Code? At other times we examine an
installation that just doesn’t seem right or in accordance
with the intent of the Code and ask, "What
sections cover this type of work or does the Code prohibit this type of installation?"
Article 682 was created to address a common
type of installation that needed to be clarified and a uniform
standard created. Prior to Article 682, electrical
installations in areas such as aeration ponds, fish farm
ponds, storm retention basins, treatment ponds, irrigation
(channels) facilities, lakes, streams, or rivers, presented a
problem as to which sections of the NEC covered them.
Prior to NEC-2005, we have had to turn to Section
110.3(B) Installation and Use, Article 555 Marinas and
Boatyards, or Article 680 for Swimming Pools, Fountains, and
Similar Installations. In exasperation we have finally had to
turn to Section 90.4, for the final word. These existing
sections have not been a good fit to the installations that
are now covered by the new Article 682. During the 2002
code-making process, a task force was assigned to address this
and prepare a proposal for NEC-2005 process.
You may be asking yourself, Why is someone
from the middle of the desert writing about bodies of water?
There is no water in Arizona! Well, for the uninformed, the
desert is full of man-made bodies of water, and we even get
rain every once in a while and when it rains it pours. We have
many retention basins that collect the storm water run off and
that double as soccer and baseball fields. If that didn’t
surprise many of you, then you will be surprised to find out
that the deserts of Arizona are also home to fish and shrimp
farms. In the city of Tempe, we have taken a normally dry
river bottom and installed two rubber inflatable dams that
hold back the Tempe Town Lake. When floodwaters come down from
the mountains, during the monsoon season, the dams are
deflated and the water is allowed to flow downstream. Doing
plan reviews and inspections on electrical installations have
been challenging since we do not have Article 682 in the code
we presently adopt.
Article 682 uses a term new to the NEC: electrical datum plane. This term addresses four
different locations, depending upon the situation. First, it
is a horizontal plane 600 mm (2 ft) above the highest tide
level under normal circumstances, in areas subject to tidal
fluctuation to the water level. Second, it is a horizontal
plane 600 mm (2 ft) above the highest water level for a body
of water, not subject to tidal fluctuations, under normal
circumstances. Third, it is a horizontal plane 600 mm (2 ft)
above the prevailing high water mark, in areas subject to
flooding or storm runoff. Fourth, for floating structures and
landing stages (floating docks), it is the horizontal plane
750 mm (30 in.) above the water level of the floating
structure or landing stage and a minimum 300 mm (12 in.) above
the level of the deck. These structures or docks are
restrained from horizontal movement, but are allowed to rise
to the levels mentioned in the first and second conditions
above and may fall with the water level.
The electrical datum plane needs to be
determined for the specific situation before the requirements
of this article can be applied. In the case of tidal
fluctuations or storm water runoff, other professionals need
to be enlisted to help determine these levels. In storm water
retention basins or other bodies of water subject to seasonal
fluctuation or in lakes, overflow spillways may be considered
when considering these levels. It must be remembered that
these levels are determined using the historical or designed
high water level, not the worst case situation that may occur
during an unexpected flood or other type of natural disaster.
Once the electrical datum plane has been
determined, the requirements of the rest of this article can
be applied. Electrical equipment and transformers not approved
for operation when submerged are not to be installed below the
electrical datum plane. Electrical service equipment is to be
located 1.5 m (5 ft) horizontally beyond the shoreline and at
least 300 mm (12 in.) above the electrical datum plane. This
service equipment is required to automatically disconnect once
the water level reaches the established electrical datum
plane. For floating structures or submersible equipment, a
disconnecting means is required to be provided and located on
land within 750 mm (30 in.) from the structure or equipment
connection and is to be located within sight of, but not
closer than 1.5 m (5 ft) horizontally beyond the shoreline;
and live parts are to be elevated at least 300 mm (12 in.)
above the electrical datum plane. GFCI protection is required
for 15- and 20-ampere single-phase, 125-volt through 250-volt
receptacles installed outdoors and also in or on floating
buildings or structures within the electrical datum plane area
that are used for storage, maintenance, or repair where
portable electrical hand tools or electrical diagnostic
equipment are used.
Grounding and bonding is similar to what
has been required in Articles 553 and 555 of earlier editions
of the NEC. One major difference is the requirement of
installing an equipotential plane adjacent to all outdoor
service equipment or disconnecting means that control
equipment in or on the water and that have metallic enclosures
and controls accessible to personnel, and that are likely to
become energized.
Long overdue, Article 682 should help us in
applying the Code to this type of installation, without
requiring the inspector to refer to sections that do not
specifically address these specific areas. It is still not a
perfect article, so the members of code-making panel 17 will
be looking forward to your proposals to NEC-2008 to
improve these requirements. Remember that without your input,
the NEC will not improve to address these types of
situations. The time is drawing near for all proposals to be
in to NFPA for NEC-2008. Get involved in the
code-making process and remember that improvements in the Code are usually from an individual who saw a need or loophole in
the Code and then took the time to submit his or her
ideas.
Jim Maldonado is senior plan check
engineer, city of Tempe, Arizona. He is also IAEI alternate
member of code-making panel 17 and 2005 president of the
Southwestern Section of IAEI.
Photos courtesy of jwestphotography.com. |
