Transcript Report on Proposals for the 2012 NESC

Proposed Changes To The 2012
National Electrical Safety Code
Oncor Electric Delivery
1
National Electrical Safety Code C2-2007
Oncor Electric Delivery
2
Schedule
 1 September 2009
 Preprint of the change proposals for incorporation into the 2010
Edition of the NESC published for distribution to the NESC
Committee and other interested parties. This opens the comment
period, by interested parties, on the submitted change proposals
and the subcommittee recommendations.
 1 May 2010
 The final date to submit comments on the submitted change
proposal and the subcommittee recommendations. All comments
and recommendations on these proposals are due to the Secretary,
NESC Committee.
Oncor Electric Delivery
3
Schedule – Cont’d
 September-October 2010

Period for NESC Subcommittee Working Groups and NESC
Subcommittees to reconsider all recommendations concerning the
proposed amendments and prepare final report.
 15 January 2011

Proposed revision of the NESC, Accredited Standards Committee
C2, submitted to NESC Committee for letter ballot and to ANSI
for concurrent public review.
Oncor Electric Delivery
4
Schedule – Cont’d
 15 May 2011

NESC Committee approved revisions of the NESC submitted to
ANSI for recognition as an ANSI Standard.
 1 August 2011

Publication of the 2012 Edition of the NESC.
Oncor Electric Delivery
5
Section 1: Introduction
Section 2: Definitions
 Several CPs proposed to significantly revise and add to
Rule 010, Purpose; Rule 11, Scope; and Section 2,
Definitions, to:

Harmonize the purpose and scope
sections of the NESC and the NEC

Mitigate conflicts between the codes

Resolve the conflict in NEC 90.2(B)(5)b
Oncor Electric Delivery
6
Rule 215C: Grounding of Circuits, Supporting
Structures, and Equipment – Non-Current
Carrying Parts
 All guys should be grounded or insulated.
 Lists several requirements for guy insulators.
 Clarifies that a guy’s electrical connection to an anchor is
not an acceptable means of grounding.
Oncor Electric Delivery
7
Rule 218:
Vegetation Management
 Recommended that title should be changed to “Vegetation
Requirements.”
 Removed phrase “vegetation management should be
performed as experience has shown to be necessary.”
Refers reader to Rule 214A2.
 Adds note to denote ANSI Standards A-300 and Z133.1 for
information regarding vegetation management.
Oncor Electric Delivery
8
Rule 230B, 251B: Ice and Wind
Loading for Clearances
 Revises method for determining sags and clearances by
elimination of the additive constant and increasing wind
pressures accordingly.
Oncor Electric Delivery
9
Clearance Zone
(for use with Rule 230B)
Clearance Zone (for use with Rule 230B)
Zone 1
Zone 2
Zone 3
Radial Thickness
of Ice (in)
0.5
0.25
Horizontal Wind
2
Pressure (lbs/ft )
o
Temperature ( F)
Constand Added to
the Resultant (lbs/ft)
Oncor Electric Delivery
4
8
4
8
9
10
0
+15
+30
0.3
0.2
0.05
10
CP3437: Rules 230B1, 250B, 250D;
Figures 230-1 & 250-1;
Tables 230-1, 230-2 & 251-1
 Revises to add a fourth loading zone for temperate island
use (below lat 25º).
 Radial thickness of ice, wind pressure, temperature and
constant are separated for altitudes 0- 9000 feet and above
9000 feet.
 No loading is specified for extreme ice and concurrent
wind for warm islands from 0- 25º lat, north or south.
Oncor Electric Delivery
11
Table 232-1, FN 7: Vertical Clearance of Wires,
Conductors, and Cables Above Ground,
Roadway, Rail, or Water Surfaces
 For clearance to services, revises the phrase “where
the height of a building does not permit the service
drop to meet these values…” to “the clearance over
residential driveways only may be reduced to…”
 Removes the subjectivity of having to judge whether
a building’s height will accommodate clearance.
Oncor Electric Delivery
12
Rule 234A: Clearance of Wires, Conductors,
Cables, and Equipment from Buildings, Rail Cars,
Swimming Pools and Other Installations- Application
 Added a reminder statement that for horizontal clearances,
both the “at rest” condition and the “blowout” condition
must both be satisfied.
Oncor Electric Delivery
13
Rule 234E1: Clearance of Wires, Conductors,
Cables or Unguarded Rigid Live Parts Installed
Over Swimming Areas With No Wind Displacement
 New wording (as a result of an interpretation request) that
clarifies that spas including whirlpools, hot tubs, jacuzzis
and other installations not suitable for swimming are not
considered swimming pools.
Oncor Electric Delivery
14
Rule 234F2, Fig 234-4b: Clearance Envelope
for Grain Bins Filled by Portable Augers,
Conveyors or Elevators
 Seeks to clarify clearance diagram to grain bins where the
vertical requirements are referenced to grade instead of to
the grain bin.
Oncor Electric Delivery
15
Oncor Electric Delivery
16
Rule 235C2b1(c): Vertical Clearance Between
Line Conductors, Additional Clearances, Sag
Related Clearances
 Requirements for vertical clearance at the supports.
 Recognizes that two vertical lines on the same support are
at the same ambient but may be at different electrical
loading and/or icing conditions.
 Removes the exception for the same utility, same
conductors at the same sags and tensions.
Oncor Electric Delivery
17
Rule 238:Vertical Clearance Between Certain
Communications and Supply Facilities Located
on the Same Structure
 Enforces official interpretation requests in ensuring that
non-conductive wood or fiberglass braces and supports for
communication conductors are not allowed in the worker
safety zone.
Oncor Electric Delivery
18
Rule 250C- Extreme Wind Loading Rule 250D
Extreme Ice With Concurrent Wind Loading
 Proposal to exclude the 60’ exemption.
 Status: Rejected- the proposals do not increase safety.
Oncor Electric Delivery
19
Proposed Changes to Rule 410A3- Arc Flash
Oncor Electric Delivery
20
Proposed Changes to Rule 410A3- Arc Flash
Oncor Electric Delivery
21
Proposed Changes to Rule 410A3- Arc Flash
 1. Take Exception 2 and put it in rule. (For work where
V< 1000 Volts: In lieu of analysis, limit exposure by
applicable work rules and wear 4 cal/cm2 clothing).
 2. Revise “…clothing made from the following
materials…” to “clothing must have an acceptable arc
rating” to make statement all inclusive.
 3. Table 410-1 reword headings and footnotes.
Oncor Electric Delivery
22
QUESTIONS?

Oncor Electric Delivery
23