Brochure

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
CAT 0 CAT II CAT III CAT IV
How to choose the best
DMM for your job
Choosing the right digital mul-
timeter (DMM) requires thinking
about what you’ll be using it for.
Evaluate your basic measure-
ment needs and job requirements
and then take a look at special
features/functions built into many
multimeters. Think about whether
you need to do basic measure-
ments, or if you need the more
advanced troubleshooting options
offered by special features.
Factors to consider:
•
Your work environment (voltage
level, types of equipment, types
of measurements, applications)
•
Specialty features/functions
(capacitance, frequency, tem-
perature, non-contact voltage,
low impedance mode, min-max
record, data logging, trending)
•
Resolution and accuracy
(6,000, 20,000, or 50,000
count resolution)
Safety
The increased occurrence and
levels of transient overvoltages
in today’s power systems have
given rise to more stringent
safety standards for electrical
measurement equipment.
Transients that ride on top of
power sources (mains, feeder
or branch circuits) can trigger
a sequence of events that
may lead to serious injury. Test
equipment must be designed
to protect people working in
this high-voltage, high-current
environment.
Measurement
category
In brief Examples
CAT 0 Electronic (Not directly
connected to mains)
• Protected electronic equipment
• Equipment connected to (source) circuits in which
measures are taken to limit transient overvoltages to
an appropriately low level
• Any high-voltage, low-energy source derived from
a high-winding resistance transformer, such as the
high-voltage section of a copier
CAT II Appliances, PCs,
and TVs
• Appliance, portable tools, and other household
and similar loads
• Outlet and long branch circuits
• Outlets at more than 10 meters (30 feet) from
CAT III source
• Outlets more than 20 meters (60 feet) from
CAT IV source
CAT III MC panels, etc. • Equipment in fixed installations, such as switchgear
and polyphase motors
• Bus and feeder in industrial plants
• Feeders and short branch circuits, distribution panel
devices
• Lighting systems in larger buildings
• Heavy appliance outlets with short connections to
service entrance
CAT IV Three-phase at utility
connection, any
outdoor conductors
• Refers to the “origin of installation,” i.e., 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