There are a number of
changes that have been introduced in 2014 that will affect people working on or near exposed live (energized)
circuits. Over the next couple of
months, I will explain a few of the most important changes detailed in NFPA 70E. In general, the
2015 edition of The Standard for
Electrical Safety in the Workplace (NFPA 70E) reflects changes that make
sense.
Before looking at the details, one must consider a holistic approach to safety to obtain a complete picture.
There are three standards that affect the interaction of people with
electrical hazards. These are the National Electric Code (NFPA 70), The Standard for Electrical Safety in the
Workplace (NFPA 70E), and Recommended
Practice for Electrical Equipment Maintenance (NFPA 70B). To workplace free from electrical hazards,
one needs to make sure that all three standards are used.
The National Electric Code (NEC) provides the basic requirements to
ensure that equipment is installed properly.
The NEC describes the “normal” operation of equipment. When equipment is designed and installed in
accordance with the NEC, at that point there is minimal potential electrical
hazards: shock hazards or arcing hazards.
For example, an electrical panel installed in accordance with the
articles in NFPA 70 Chapter 408 does not present a shock or arc flash hazard
when the deadfront covers are properly installed.
The Recommended Practice for Electrical Equipment Maintenance standard
provides the basic requirements for properly maintaining equipment. This includes the development of an
electrical preventative maintenance (EPM) program and recommended practices for
equipment and conductors. NFPA 70B
provides the requirements after the equipment has been installed and operated,
and subsequently temporarily removed (de-energized) from service for
maintenance. For example, an electrical
panel has been de-energized, locked out and tagged out, and is undergoing
examination and testing of the panelboard itself, the internal molded case
circuit breakers (MCCBs), and the conductors entering and exiting the
panelboard.
The Standard for Electrical Safety in the Workplace provides the
basic requirements for working on equipment in an “abnormal” condition. It is an abnormal condition as the equipment
is not being used as intended nor is it being maintained. For example, an electrical panelboard
undergoing voltage testing to determine if circuits are operating properly is
an abnormal condition. In this scenario,
the deadfront covers are removed and personnel are exposed to live (energized)
parts. Because there is an interaction
with exposed live (energized) circuits, there is a shock hazard risk and an arc
flash hazard risk.
Many consider that the safety of
personnel from shock and arc flash hazards are only associated with the
practices detailed in The Standard for
Electrical Safety in the Workplace.
However, this is not true. Safety
from electrical hazards starts with the proper installation of equipment,
followed by the proper servicing and maintenance of the equipment. When the equipment is properly installed and
maintained, then qualified personnel following safe work practices and using
proper personal protective equipment (PPE) can work on exposed live (energized)
circuits under specific conditions.
