CP 2504
Submitter
Lawrence Slavin
Proposed Change
Revise Rule 423D (p. 223) as follows:
D.
Excavation
1.
Cables and other buried utilities in the immediate vicinity shall be located,
to the extent practical, prior to excavating. When using guided boring or
directional drilling for placing new cables, existing utilities shall be
exposed where the new cable path crosses such facilities.
NOTE: The latest edition of the following document is among those
available for providing information on guided boring, also known as
directional drilling: IEEE Std 1333-1994, IEEE Guide for Installation of
Cable Using the Guided Boring Method.
2.
Hand tools used for excavating in the vicinity of energized supply cables
shall be equipped with handles made of nonconductive material.
NOTE: Air- or water-vacuum tools are available for carefully digging in
the vicinity of existing utilities, to minimize the possibility of damaging
such facilities.
3.
Mechanized equipment should not be used to excavate in close proximity
to cables and other buried utilities.
EXCEPTION: Guided boring may be used to place a new cable above or
below existing utilities, providing the existing facilities have been exposed
at the crossing, as required in Rule 423D1.
4.
If a gas or fuel line is broken or damaged, employees shall:
a.
Leave the excavation open
b.
Extinguish flames that could ignite the escaping gas or fuel
c.
Notify the proper authority
d.
Keep the public away until the condition is under control
5.
When a worker is required to perform tasks in trenches or excavations
where a cave-in hazard exists or the trench or excavation is in excess of
1.5 m (5 ft) in depth, shoring, sloping, or shielding methods shall be used
to provide employee protection.
Supporting Comment
IEEE Std 1333-1994, IEEE Guide for Installation of Cable Using the Guided Boring
Method, provides a description and guidelines for the use of guided boring, also known as
directional drilling—or more precisely, as mini-horizontal directional drilling, to indicate
the small scale applicability such as for residential applications with relatively short
boring distances (several hundred ft maximum) and shallow depths (e.g., 20-ft
maximum). Larger, more sophisticated equipment would be used for maxi-horizontal
directional drilling, for river crossings, and distances as great as 5000 ft. These
directional drilling techniques allow the construction equipment to be mounted at the
ground surface, avoiding the need for significant trenches at the ends of the bore path.
Originally developed and introduced by the electric power industry (EPRI-sponsored)
within the past 10–15 years, guided boring (mini-horizontal directional drilling) is now
widely used by the power and telecommunications industries for distribution cable
upgrades in established areas with buried facilities. The technique avoids the need for
unsightly, inconvenient continuous trenching operations and the associated restoration
expenses. The NESC should recognize the existence of this commonly used, important
cable installation technique in order to maintain the relevance of the standard, as well as
to provide appropriate rules for safety.
One feature of the guided boring method is the ability to place new cable above or below
existing facilities. Such operations, however, must be accompanied by stringent safety
rules, including the identification, location, and possible exposure of existing utilities in
the vicinity of the new construction activities. This need is emphasized by the inability to
actually see the progress of the new cable path as the boring proceeds beneath the ground.
In particular, utilities must be carefully exposed, using appropriate tools (e.g., hand tools,
air- or water-vacuum systems, etc.) at all intended crossings of the new path with existing
cables or utility lines. Thus, the progress of the boring and location of the drill head may
be visually confirmed to be safely beneath or above the existing lines being crossed.
Subcommittee 8 Recommendation
Accept as modified.
Subcommittee 8 Comment
Revise Rule 423D (p. 223) as follows:
D.
Excavation
1.
Cables and other buried utilities in the immediate vicinity shall be located,
to the extent practical, prior to excavating.
2.
When using guided boring or directional drilling for placing new cables,
existing utilities should be exposed where the new cable path crosses such
facilities. (Include a reference to IEEE Std 1333-1994 in Appendix B,
Bibliography.)
3. 2. Hand tools used for excavating in the vicinity of energized supply cables
shall be equipped with handles made of nonconductive material.
3. 4. Mechanized equipment should not be used to excavate in close proximity
to cables and other buried utilities.
4. 5.
If a gas or fuel line is broken or damaged, employees shall:
a.
Leave the excavation open
b.
Extinguish flames that could ignite the escaping gas or fuel
c.
Notify the proper authority
d.
Keep the public away until the condition is under control
5. 6. When a worker is required to perform tasks in trenches or excavations
where a cave-in hazard exists or the trench or excavation is in excess of
1.5 m (5 ft) in depth, shoring, sloping, or shielding methods shall be used
to provide employee protection.
Vote on Subcommittee 8 Recommendation
Affirmative: (18) Brooks, Brubaker, Doering, Erga, Fass, Grose, Henry, Hunt, Kientz,
Mitchell, Poholski, Schweitzer, Spadafore, Theis, Tomaseski, Tootle, Tuggle, White
Negative: (1) McKinney
Abstention: (0)
Explanation of Vote
McKinney: Given 2-ft location variance, parallel cabling in a small right-of-way (row)
could result in a large amount of exposure. Also, the rule may promote excessive
exposure of electric services owned by the utility or customer when telecommunication
lines are installed.