Niche Market Testing
The Utility Industry
and PPE Requirements
by Lynn Hamrick
ESCO Energy Services
ETC ETC
A
s we discussed in an earlier
NETA World article, every
industry in the United States
has been struggling to meet the requirements of NFPA 70E except the
utility industry. As part of that discussion, it was pointed out that the
utility industry uses the Institute of
Electrical and Electronic Engineers, Inc. (IEEE) Standard
C2, National Electrical Safety Code (NESC) and Occupation
Safety and Health Association’s (OSHA’s) 29CFR1910,
Subpart R (1910.269) for equivalent requirements with
transmission, distribution, and generation facilities. This
For this discussion, electrical hazards will be divided
into shock-flash and arc-flash related hazards. To select the
appropriate PPE for a given task, the degree and extent of
each hazard should be determined with the applicable PPE
requirements combined to enable the task to be performed
safely. Therefore, a shock-hazard analysis and an arc-flash
hazard analysis shall be performed.
Shock Hazard Analysis
For determining the degree and extent of a shock hazard,
one must first determine the maximum voltage level of the
exposed energized circuit or equipment. Upon determining
the applicable voltage, the following table should be applied for determining the appropriate minimum approach
distance for that voltage:
article, based on the referenced texts, summarizes personal
protection equipment (PPE) requirements for performing
energized electrical work in the utility environment.
As is the case in the industrial environment, only qualified electrical workers shall be allowed to work on or near
energized electrical circuits and equipment in the utility
environment. Additionally, qualified workers shall be trained
and competent in the decision-making process necessary
to determine the degree and extent of an electrical hazard
and the PPE and job planning necessary to perform a task
safely. Qualified workers shall also be trained and competent
in the proper use of the special precautionary techniques,
personal protective equipment, insulating and shielding
materials, and insulated tools for working on or near exposed
energized parts of electric equipment.
www.netaworld.org If the applicable minimum approach distance is to be
breached in the performance of the work, shock-related
PPE is required.
Shock-Related PPE Requirements
Shock-related PPE shall meet the requirements of
29CFR1910.137 (Subpart I). This shock-related PPE shall
include the implementation of voltage-rated insulation
material to protect the worker. This material can take the
form of insulating blankets, covers, line hose, gloves, and
Spring 2009 NETA WORLD
sleeves. For voltages >1000V, where voltage-rated gloves are
required, voltage-rated sleeves shall also be applied.
The following specific requirements apply to insulating blankets, covers, line hose, gloves, and sleeves made of
rubber:
1. Maximum use voltages shall conform to those listed in
the table provided.
2. Insulating equipment shall be inspected for damage
before each day’s use and immediately following any incident that can reasonably be suspected of having caused
damage. Insulating gloves shall be given an air test along
with the inspection.
3. Insulating equipment with any of the following defects
may not be used:
• A hole, tear, puncture, or cut;
• Ozone cutting or ozone checking (the cutting action
produced by ozone on rubber under mechanical stress
into a series of interlacing cracks)
• An embedded foreign object
• Any of the following texture changes: swelling, softening, hardening, or becoming sticky or inelastic
• Any other defect that damages the insulating
properties.
4. Insulating equipment found to have other defects that
might affect its insulating properties shall be removed
from service and returned for testing.
5. Insulating equipment shall be cleaned as needed to remove foreign substances.
6. Insulating equipment shall be stored in such a location
and in such a manner as to protect it from light, temperature extremes, excessive humidity, ozone, and other
injurious substances and conditions.
7. Electrical protective equipment shall be subjected to
periodic electrical tests. The employer shall certify that
equipment has been tested in accordance with the requirements of Subpart I. The certification shall identify
the equipment that passed the test and the date it was
tested. Maximum use and test voltages shall be in accordance with the tables below.
NETA WORLD Spring 2009
Arc-Flash Hazard Analysis
For determining the degree and extent of an arc-flash
hazard, one must consider voltage, the arcing fault current,
and the fault clearing time. With this information, the
incident energy (in cal/cm^2) is determined at a suggested
working distance of 15 inches. This level of incident energy is then used to determine the arc-flash-related PPE
requirements.
Arc-Flash-Related PPE Requirements
Where the incident energy as been determined by analysis, the following table could be used in determining the
arc-flash-related PPE requirements. This table was derived
using the basic NFPA 70E hazard risk categories with adjustments being made to accommodate NESC criteria.
Where the incident energy as not been determined,
the following table should be used for evaluating the arcflash-related hazard risk category and associated PPE
requirements:
If inadequate information is available to determine the
degree or extent of the arc-flash hazard, the utility’s electrical
engineer should be notified and consulted for determining appropriate arc-flash-related PPE requirements. For
secondary systems (<1000V) in the utility environment,
the NESC states that incident energies “can be excessive.”
Therefore, work rules and engineering controls shall be
utilized to limit and minimize worker exposure to the arc
flash hazard. At a minimum for secondary circuits <1000V,
the NESC suggests that arc-rated clothing systems of 4
cal/cm2 be utilized. Based on experience with performing
arc-flash analyses in the industrial environment, this level
of protection will be inadequate at the secondary of larger
transformers. Therefore, it is suggested that an arc-rated
clothing system at least 8 cal/cm2 be utilized with additional
“work rules and engineering controls,” including the isolation of the transformer.
When exposed to an electric arc or flame, clothing made
from acetate, nylon, polyester, or polypropylene shall not
be worn.
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Summary
The utility industry is required to meet the comparable
NESC requirements for their transmission, distribution,
and generation facilities. NESC requirements include the
assessment of arc-flash hazards for these facilities. In general,
the PPE requirements suggested in the NESC are similar
to NFPA 70E requirements; however, NESC requirements
suggest different criteria when comparing incident energies
with effective hazard risk categories. As in the industrial
environment, an arc-flash hazard assessment should be used
in the utility environment to determine the extent of the
arc-flash hazards. The appropriate application of PPE and
special precautionary techniques should then be employed
to minimize the exposure to the worker.
As Operations Manager of ESCO Energy Services Company, Lynn
brings over 25 years of working knowledge in design, permitting, construction, and startup of mechanical, electrical, and instrumentation and
controls projects as well as experience in the operation and maintenance
of facilities.
Lynn is a Professional Engineer, Certified Energy Manager and has
a BS in Nuclear Engineering from the University of Tennessee.
The following specific requirements apply to arc-flashrelated PPE:
1. Arc-flash-rated PPE shall be inspected for damage
before each day’s use and immediately following any incident that can reasonably be suspected of having caused
damage.
2. Arc-flash-rated PPE with any of the following defects
may not be used:
• A hole, tear, puncture, or cut
• An embedded foreign object
• Any other defect that damages the flame-resistant
(FR) properties.
3. Arc-flash-rated PPE found to have other defects that
might affect its flame resistant properties shall be removed from service.
4. Arc flash-rated PPE shall be cleaned as needed to remove
foreign substances. For FR-rated clothing, manufacturer’s
recommendations for cleaning shall be mandated.
5. FR-rated clothing shall be replaced at least every twoto-three years to ensure that it meets its stated FR
characteristics.
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