[Federal Register Volume 73, Number 205 (Wednesday, October 22, 2008)]
[Proposed Rules]
[Pages 62942-62945]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-25079]


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DEPARTMENT OF LABOR

Occupational Safety and Health Administration

29 CFR Parts 1910 and 1926

[Docket OSHA-S215-2006-0063]
RIN 1218-AB67


Electric Power Generation, Transmission, and Distribution; 
Electrical Protective Equipment; Limited Reopening of Record

AGENCY: Occupational Safety and Health Administration (OSHA), U.S. 
Department of Labor.

ACTION: Notice of limited reopening of rulemaking record.

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SUMMARY: On June 15, 2005, OSHA published a proposed rule to revise the 
general industry and construction standards for electric power 
generation, transmission, and distribution work and for electrical 
protective equipment. Public comments were received, a hearing was 
held, and the final posthearing briefs were due on July 14, 2006.
    The proposed general industry and construction standards for 
electric power generation, transmission, and distribution work included 
revised minimum approach distance tables. Those tables limit how close 
an employee (or a conductive object he or she is contacting) may get to 
an energized circuit part. After the rulemaking record on the proposal 
closed, the technical committee responsible for developing the tables 
in the consensus standards on which the proposal was based discovered 
what in their view was an error in their calculation of minimum 
approach distances for certain voltages.
    OSHA is reopening the record on this proposal to obtain comments 
related to the affected minimum approach distances. The record will 
remain open on this limited basis for 30 days.

DATES: Comments must be postmarked no later than November 21, 2008.

ADDRESSES: You may submit comments, identified by Docket No. OSHA-S215-
2006-0063, by any of the following methods:
     Federal eRulemaking Portal: http://www.regulations.gov. 
Follow the instructions for submitting comments.
     Fax: If your comments, including attachments, do not 
exceed 10 pages, you may fax them to the OSHA Docket Office at (202) 
693-1648.
     Mail, hand delivery, express mail, messenger, or courier 
service: You must submit two copies of your comments and attachments to 
the OSHA Docket Office, Docket No. OSHA-S215-2006-0063, U.S. Department 
of Labor, Room N-2625, 200 Constitution Avenue, NW., Washington, DC 
20210; telephone (202) 693-2350 (OSHA's TTY number is (877) 889-5627). 
Deliveries (hand, express mail, messenger, and courier service) are 
accepted during the Department of Labor's and Docket Office's normal 
business hours, 8:15 a.m.-4:45 p.m., e.s.t.
    Instructions: All submissions must include the agency name and the 
docket number (Docket No. OSHA-S215-2006-0063) or Regulatory 
Information Number (RIN 1218-AB67) for this rulemaking. All comments 
received will be posted without change to http://dockets.osha.gov, 
including any personal information provided.
    Docket: To read or download comments and materials submitted in 
response to this Federal Register notice, go to Docket OSHA-S215-2006-
0063 at http://www.regulations.gov or at the OSHA Docket Office at the 
previously listed address. All comments and submissions are listed in 
the http://www.regulations.gov index. However, some information (for 
example, copyrighted material) is not publicly available to read or 
download through that Web page. All comments and submissions, including 
copyrighted material, are available for inspection and copying at the 
OSHA Docket Office.
    Electronic copies of this Federal Register document are available 
at http://www.regulations.gov. This document, as well as news releases 
and other relevant information, also are available at OSHA's Web page 
at http://www.osha.gov.

FOR FURTHER INFORMATION CONTACT: General information and press 
inquiries: Contact Ms. Jennifer Ashley, Office of Communications, Room 
N-3647, OSHA, U.S. Department of Labor, 200 Constitution Avenue, NW., 
Washington, DC 20210; telephone (202) 693-1999.

SUPPLEMENTARY INFORMATION: On June 15, 2005, OSHA issued a proposed 
rule to revise the general industry and construction standards for 
electric power generation, transmission, and distribution work and for 
electrical protective equipment (70 FR 34822). The Agency solicited 
public comments and held a public hearing on March 6 through 14, 2006. 
Administrative Law Judge William Colwell set a deadline of July 14, 
2006, for the filing of written comments, summations, position 
statements, and briefs.
    The proposed requirements for electric power generation, 
transmission, and distribution work for general industry and 
construction would be contained in 29 CFR 1910.269 and 29 CFR part 
1926, subpart V (Sec. Sec.  1926.950 through 1926.968), respectively. 
Proposed Sec.  1926.960(c)(1) would require employees to maintain 
minimum approach distances from exposed energized parts. The minimum 
approach distances are specified in proposed Tables V-2 through V-6. 
Existing Sec.  1910.269(l)(2) and proposed Tables R-6 through R-10 
contain equivalent requirements for general industry.
    OSHA developed the minimum approach distance tables in the proposal 
using the following principles (see 70 FR 34862):
     ANSI/IEEE \1\ Standard 516-1987 was to be the electrical 
basis for approach distances: Table 4 (Alternating Current) and Table 5 
(Direct Current) for voltages above 72.5 kV. Lower voltages were to be 
based on ANSI/IEEE Standard 4. The application of ANSI/IEEE Standard 
516-1987 was inclusive of the formula used by that standard to derive 
electrical clearance distances.
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    \1\ ANSI is the American National Standards Institute. IEEE is 
the Institute of Electrical and Electronics Engineers, Inc.
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     Altitude correction factors were to be in accordance with 
ANSI/IEEE Standard 516-1987, Table 1.
     The maximum design transient overvoltage data to be used 
in the development of the basic approach distance tables were:

[cir] 3.0 per unit for voltages of 362 kV and less
[cir] 2.4 per unit for 500 to 550 kV
[cir] 2.0 per unit for 765 to 800 kV

     All phase-to-phase values were to be calculated from the 
EPRI \2\ Transmission Line Reference Book for 115 to 138 kV.
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    \2\ EPRI is the Electric Power Research Institute.
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     An inadvertent movement factor (ergonomic component) 
intended to account for errors in judging the approach distance was to 
be added to all basic electrical approach distances (electrical 
component) for all voltage ranges. A distance of 0.31 meters (1 foot) 
was to be added to all voltage ranges. An additional 0.3 meters (1 
foot) was to be added to voltage ranges below 72.6 kV.

[[Page 62943]]

     The voltage reduction allowance for controlled maximum 
transient overvoltage was to be such that the minimum allowable 
approach distance was not less than the given approach distance 
specified for the highest voltage of the given range.
     The transient overvoltage tables were to be applied only 
at voltage ranges inclusive of 72.6 kV to 800 kV. All tables were to be 
established using the higher voltage of each separate voltage range.
    As noted in Appendix B to existing Sec.  1910.269 and in Appendix B 
to proposed subpart V, the following equation is used to calculate the 
electrical component of the minimum approach distance for voltages of 
72.6 kV to 800 kV:
[GRAPHIC] [TIFF OMITTED] TP22OC08.000

Where:

D = Electrical component of the minimum approach distance in air in 
feet
C = 0.01 to take care of correction factors associated with the 
variation of gap sparkover with voltage
a = A factor relating to the saturation of air at voltages \3\ of 
345 kV or higher
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    \3\ This voltage is the maximum transient overvoltage.
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pu = Maximum anticipated transient overvoltage, in per unit (p.u.)
Vmax = Maximum rms system line-to-ground voltage in kilovolts--it 
should be the ``actual'' maximum, or the normal highest voltage for 
the range (for example, 10 percent above the nominal voltage).

Source: Formula developed from ANSI/ IEEE Standard No. 516-1987.

    For phase-to-phase exposures, the maximum phase-to-phase transient 
overvoltage must be used to calculate minimum approach distances from 
one phase to another. As noted in Appendix B to existing Sec.  1910.269 
and in Appendix B to proposed subpart V, the following equation is used 
in determining the phase-to-phase maximum transient overvoltage based 
on the per unit of the system nominal voltage phase-to-ground crest:
[GRAPHIC] [TIFF OMITTED] TP22OC08.001

Where:

pup = p.u. phase-to-phase maximum transient overvoltage
pug = p.u. phase-to-ground maximum transient overvoltage.

    This value was to be used in Equation (1) to calculate the phase-
to-phase minimum approach distance (MAD).
    The technical committees responsible for ANSI/IEEE and the National 
Electrical Safety Code (NESC, ANSI C2) calculated minimum approach 
distances based on these equations. Because OSHA intended to use the 
same methodology, it relied on the technical committees' calculations 
as they appeared in the two consensus standards and carried those 
distances into the proposed standard.
    During the most recent revision cycle for ANSI/IEEE Standard 516, 
the IEEE technical committee responsible for revising that standard 
identified what in their view was an error in the calculations of 
phase-to-phase minimum approach distances for nominal voltages 230 kV 
and higher. At these voltages, the saturation factor, a, which appears 
in Equation (1), varies depending upon the voltage. The value of a 
increases with increasing voltage. The NESC subcommittee originally 
calculated the phase-to-phase minimum approach distances using a value 
for the saturation factor, a, corresponding to the phase-to-ground 
maximum transient overvoltage rather than the maximum phase-to-phase 
transient overvoltage.\4\ Because the MADs used in OSHA's 2005 proposal 
were taken from the consensus standard, OSHA wants to obtain comments 
on whether changes are necessary to the tables as proposed.
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    \4\ ANSI/IEEE Standard 516-1987 did not contain distances for 
phase-to-phase exposures. The NESC subcommittee derived them by 
applying the IEEE equation to the phase-to-phase temporary 
overvoltages calculated using Equation (2).
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    The IEEE committee proposed a correction in a draft revised IEEE 
Standard 516 (Draft 9).\5\ Table 1 shows the difference 
between the minimum approach distances in that draft IEEE Standard 516 
and those contained in proposed Sec.  1910.269 Table R-6 and proposed 
Subpart V Table V-2 for voltages over 72.5 kV. A subsequent draft from 
the IEEE committee (Draft 10) dropped values for voltages with 
temporary overvoltages exceeding 1600 kV.\6\ Draft 10 leaves 
the determination of these values to ``good engineering judgment.''
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    \5\ This document is available for inspection and copying in the 
Docket Office at the address listed in the ADDRESSES section of this 
notice.
    \6\ This document is also available for inspection and copying 
in the Docket Office at the address listed in the ADDRESSES section 
of this notice.

                                Table 1--Comparison of Minimum Approach Distances
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                                                                         Distance (m)
                                             -------------------------------------------------------------------
                                                  Phase-to-ground exposure           Phase-to-phase exposure
 Nominal voltage in kilovolts phase-to-phase -------------------------------------------------------------------
                                                                   Proposed                          Proposed
                                               Draft IEEE 516  tables R-6  and   Draft IEEE 516  tables R-6  and
                                                    \1\              V-2              \1\              V-2
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72.6 to 121.................................            1.01             0.95             1.36             1.29
138 to 145..................................            1.15             1.09             1.57             1.50
161 to 169..................................            1.29             1.22             1.85             1.71
230 to 242..................................            1.71             1.59             2.91             2.27
345 to 362..................................            2.72             2.59             5.13             3.80
500 to 550..................................            3.54             3.42             6.89             5.50

[[Page 62944]]

 
765 to 800..................................            4.64             4.53             9.35             7.91
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\1\ Draft 9 of IEEE Standard 516 provides separate minimum approach distances for exposures with and
  without tools in the air gap. The distances in the table are for tools in the air gap (called ``minimum tool
  insulation distances'' in the IEEE standard.). The NESC minimum approach distances tables are derived from the
  distances in IEEE Standard 516 corresponding to exposures with tools in the air gap.

    As can be seen from Table 1, the IEEE's proposed approach from 
Draft 9 results in a substantial increase in MAD for phase-to-
phase exposures at voltages of 230 kV and higher.
    For purposes of the public's consideration of the issues in this 
reopening notice, OSHA points out the following technical issues:
    1. For voltages over 72.5 kV, the electrical component of the 
minimum approach distances \7\ in OSHA's proposal is based on testing 
of rod-to-rod gaps performed by 13 laboratories. This testing extends 
to approximately 1.6 MV. This voltage is sufficient to cover the 
maximum transient overvoltage for all phase-to-ground exposures. 
However, it does not extend to the maximum transient overvoltages for 
phase-to-phase exposures of voltages 362 kV and higher, as shown in 
Table 2.
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    \7\ The electrical component of the minimum approach distance is 
called ``minimum tool insulation distance'' or MTID in the IEEE 
draft.

                 Table 2--Maximum Transient Overvoltages
------------------------------------------------------------------------
                                       Maximum transient overvoltage (in
                        Maximum                       kV)
  System voltage    anticipated per- -----------------------------------
   (in kV) Vmax      unit transient    Phase-to-ground   Phase-to-phase
                     overvoltage pu       exposure          exposure
------------------------------------------------------------------------
            362                3.0               1086              1665
            552                2.4               1325              2208
            800                2.0               2208              2880
------------------------------------------------------------------------
Note: The maximum transient overvoltage for phase-to-ground exposure
  equals Vmax x pu. The maximum overvoltage for phase-to-phase exposures
  equals Vmax x (pu + 1.6).

    In Draft 9, the IEEE committee addressed this issue by 
extending the equations used for calculating the minimum air insulation 
distance beyond the highest voltage covered by the test data. Other 
approaches using the same criteria upon which the minimum approach 
distances are based could include: (1) Using available test data for 
conductor-to-conductor gaps and converting them to equivalent rod-to-
rod values, and (2) commissioning further tests.
    2. IEEE Drafts 9 and 10 also include other 
refinements of the method used to calculate minimum approach distances 
intended to make the calculations more precise and repeatable. For 
example, the saturation factor is now based on equations resulting from 
curve fitting the test data rather than from reading the value directly 
from a graph of these data.
    3. If the minimum approach distances are based on the minimum tool 
insulation distance, as is done in the NESC, there would be additional 
slight increases in MAD for all voltages of 72.6 kV and higher with 
both phase-to-ground and phase-to-phase exposures.
    In light of the IEEE committee's draft revisions, OSHA is reopening 
the record on the electric power generation, transmission, and 
distribution standard to invite comments, evidence, and data on the 
limited question of whether the Agency should adopt minimum approach 
distances different from those proposed for voltages of 72.6 kV and 
higher. The Agency strives to adopt a final rule that is based on sound 
and up-to-date engineering, and scientific principles and is 
specifically inviting comments on the following questions:
    1. Should OSHA adopt MADs that are different from those proposed 
for voltages of 72.6 kV and higher and, if so, should it adopt the 
distances in Draft 9 or 10 of IEEE Standard 516?
    2. Are there methods other than those in Drafts 9 and 
10 of IEEE Standard 516 that would be more appropriate in the 
calculation of MAD for maximum transient overvoltages beyond existing 
data for rod-to-rod gaps?
    3. Should MAD for voltages of 72.6 kV and higher be based on the 
minimum tool insulation distance as is the case in the 2007 NESC?
    4. Should the final rule include separate minimum approach distance 
tables for air gaps and for tools as is done in Drafts 9 and 
10 of IEEE Standard 516?
    OSHA is reopening the record solely on issues related to minimum 
approach distances for voltages of 72.6 kV and higher. The record is 
not being reopened on any other issue.

List of Subjects in 29 CFR Parts 1910 and 1926

    Electric power, Fire prevention, Hazardous substances, Occupational 
safety and health, Safety.

Authority and Signature

    This document was prepared under the direction of Edwin G. Foulke, 
Jr., Assistant Secretary of Labor for Occupational Safety and Health, 
U.S. Department of Labor, 200 Constitution Avenue, NW., Washington, DC 
20210. It is issued pursuant to sections 4, 6, and 8 of the 
Occupational Safety and Health Act of 1970 (29 U.S.C. 653, 655, 657),

[[Page 62945]]

Secretary's Order 5-2007 (72 FR 31160), and 29 CFR Part 1911.

    Signed at Washington, DC, this 16th day of October 2008.
Edwin G. Foulke, Jr.
Assistant Secretary of Labor for Occupational Safety and Health.
[FR Doc. E8-25079 Filed 10-21-08; 8:45 am]
BILLING CODE 4510-26-P