Application Note

4 Fluke Corporation Who sets the rules for electrical testing and safety?
ANSI/ISA S82.02
Service
Entrance
Meter
Meter
Service
Entrance
Meter
Outbuilding
Outbuilding
Transformer
Underground Service
Underground Service
Service
Entrance
Cat I
•
Electronic
equipment
•
Low energy
equipment
with transient
limiting
protection
•
Any high-voltage,
low-energy
source derived
from a
high-winding
resistance
transformer
Cat II
•
Appliances and
portable tools
•
Outlets and long
branch circuits
– Outlets at
more than
10 m (30 ft.)
from CAT III
source
– Outlets at
more than
20 m (60 ft.)
from CAT IV
source
Cat IV
•
Origin of installation: where
low-voltage connection is made
to utility power
•
Electricity meters, primary
overcurrent protection equipment
•
Outside and service entrance
•
Service drop from pole to building
•
Run between meter and panel
•
Overhead line to detached
building
•
Underground line to well pump
Cat III
•
Equipment in fixed installations:
switchgear and three-phase motors
•
Bus and feeder in industrial plants
•
Feeders and short branch circuits
•
Distribution panel devices
•
Heavy appliance outlets with short
connections to service entrance
•
Large lighting systems
standards for voltage test equip-
ment used in environments of
up to 1000 volts. The pertinent
standards include ANSI S82.02,
CSA 22.2-1010.1 and IEC 61010.
These standards cover systems
of 1000 volts or less, including
480-volt and 600-volt, three-
phase circuits. For the first time,
these standards differentiate the
transient hazard by location and
potential for harm, as well as the
voltage level.
In addition, the 2000 edition
of IEC 61010 requires that mul-
timeters and similar equipment
shall not cause a shock, fire,
arcing or explosion hazard even
if subjected to operator error (for
instance, connecting the meter to
an energized circuit when set
to
the ohms position). Fluke meters
not only protect the user in such
circumstances—they also protect
themselves, and keep working.
ANSI and CSA are now in the
process of adopting these more
stringent IEC standards.
OSHA electrical safety regula-
tion 1910 Subpart S refers to
several ANSI standards. The key
ANSI standards involving electri-
cal safety are ANSI C33.27-74
(Safety Standard for Outlet Boxes
and Fittings for Use in Hazard-
ous Locations) and ANSI S82.02
(see below), which provides
important safety rules for electri-
cal test instruments. ANSI C2-81
(National Electrical Safety Code)
deals with electric installations
of more than 1000 volts, an area
beyond the scope of this article.
Key Point:
•
Employers and technicians
should be familiar with ANSI
electrical safety standards
C33.27-74 and S82.02 and,
if applicable, C2-81.
IEEE helps calculate arc
flash hazard
Another authority in safety is
the Institute of Electrical and
Electronics Engineers. IEEE
1584-2002, Guide for Performing
Arc-Flash Hazard Calculations,
(amended as IEEE 1584a in Sep-
tember 2004) does just what its
title suggests, providing techni-
cal information employers can
use to determine the arc flash
hazards present in the work-
place. IEEE publishes a number
of other useful safety standards
and practice guides, including the
twelve-volume IEEE Color Books
series.
Key safety rules from
international partners
To make electrical measure-
ments safely, it pays to stretch
your horizons. Some of the most
important safety guidelines for
electrical measurement have
been developed in cooperation
with the IEC, the leading global
organization that prepares and
publishes international standards
for all electrical and related
technologies.
ANSI, the Canadian Standards
Association (CSA), and the IEC
have created more stringent
These standards establish an
important four-category system
for rating the electrical hazards
electricians face when taking
measurements on so-called “low
voltage” equipment—up to 1000
volts.
ANSI, CSA and IEC define
four measurement categories of
over-voltage transient impulses
(voltage spikes). The rule of
thumb is that the closer the tech-
nician is working to the power
source, the greater the danger
and the higher the measurement
category number. Lower category
installations usually have greater
impedance, which dampens
transients and helps limit the
fault current that can feed an arc.
•
CAT (Category) IV is asso-
ciated with the origin of
installation. This refers to
power lines at the utility con-
nection, as well as the service
entrance. It also includes
outside overhead and under-
ground cable runs, since both
may be affected by lightning.