Warranty
Warranty malfunctions occurring under conditions of normal
use in conformity with the Instruction Manual and Product Pre-
cautionary Markings will be repaired free of charge. This war-
ranty is valid for a period of three (3) years from the date of
purchase. Please contact the distributor from which you pur-
chased the product for further information on warranty provi-
sions.
Introduction
Thank you for purchasing the HIOKI “Model 3120 VOLTAGE
DETECTOR.” To obtain maximum performance from the instru-
ment, please read this manual first, and keep it handy for future
reference.
Overview
This noncontact type of voltage detector unit enables the hot-
line state of AC voltage to be checked through the wire or cable
covering.
Initial Inspection
When you receive the instrument, inspect it carefully to ensure
that no damage occurred during shipping. If damage is evident,
or if it fails to operate according to the specifications, contact
your dealer or Hioki representative.
Maintenance and Service
• To clean the instrument, wipe it gently with a soft cloth moist-
ened with water or mild detergent. Never use solvents such
as benzene, alcohol, acetone, ether, ketones, thinners or
gasoline, as they can deform and discolor the case.
• If the instrument seems to be malfunctioning, confirm that the
batteries are not discharged, before contacting your dealer or
Hioki representative.
This manual contains information and warnings essential for
safe operation of the instrument and for maintaining it in safe
operating condition. Before using it, be sure to carefully readthe
following safety precautions.
Safety Symbol
The following symbolsin this manual indicatethe relative impor-
tance of cautions and warnings.
Measurement categories
This instrument complies with CAT IV (1000 V) safety require-
ments. To ensure safe operation of measurement instruments,
IEC 61010 establishes safety standards for various electrical
environments, categorized as CAT II to CAT IV, and called mea-
surement categories.
CAT II : Primary electrical circuits in equipment connected to
an AC electrical outlet by a power cord (portable tools,
household appliances, etc.)
CAT II covers directly measuring electrical outlet re-
ceptacles.
CAT III :Primary electrical circuits of heavy equipment (fixed in-
stallations) connected directly to the distribution panel,
and feeders from the distribution panel to outlets.
CAT IV: The circuit from the service drop to the service en-
trance, and to the power meter and primary overcur-
rent protection device (distribution panel).
Using a measurement instrument in anenvironment designated
with a higher-numbered category than that for which the instru-
ment is rated could result in a severe accident, and must be
carefully avoided.
Use of a measurement instrument that is not CAT-rated in CAT
II to CAT IV measurement applications could result in a severe
accident, and must be carefully avoided.
Follow these precautions to ensure safe operation and to obtain
the full benefits of the various functions.
Performance Check and Voltage Detection
December 2013 Revised edition 5
Printed in Japan
3120A981-05 13-12H
3120
VOLTAGE
DETECTOR
Instruction Manual
Safety
This instrument is designed to comply with IEC 61010
Safety Standards, and has been thoroughly tested for
safety prior to shipment. However, mishandling during
use could result in injury or death, as well as damage to
the instrument. Using the instrument in a way not
described in this manual may negate the provided safety
features. Be certain that you understand the instructions
and precautions in the manual before use. We disclaim
any responsibility for accidents or injuries not resulting
directly from instrument defects.
In the manual, the symbol indicates particularly important
information that the user should read before using the instrument.
The symbol printed on the instrument indicates that the user
should refer to a corresponding topic in the manual (marked with
the symbol) before using the relevant function.
Indicates a double-insulated device.
Indicates AC (Alternating Current).
Indicates that incorrect operation presents an extreme haz-
ard that could result in serious injury or death to the user.
Indicates that incorrect operation presents a significant
hazard that could result in serious injury or death to the
user.
Indicates that incorrect operation presents a possibility of
injury to the user or damage to the device.
Indicates advisory items related to performance or correct
operation of the instrument.
Usage Notes
• This instrument is designed for use indoors. It can be oper-
ated at temperatures between 0 and 40°C without degrading
safety.
• This instrument is not designed to be entirely water- or dust-
proof. Do not use it in an especially dusty environment, nor
where it might be splashed with liquid. This may cause dam-
age.
• To avoid damage to the instrument, protect it from physical
shock when transporting and handling. Be especially careful
to avoid physical shock from dropping.
A weak green light indicates dead battery. Replace the batteries
immediately.
Detection
The maximum rated voltage between input terminals and
ground is 1000 VAC. Attempting to measure voltages
exceeding 1000 V with respect to ground could damage
the instrument and result in personal injury.
• The green LED indicates battery consumption but is not a
guarantee of the performance of the instrument. Be sure to
check its performance using a known power source (e.g., AC
outlet) prior to use.
• The 3120 voltage detector works using a live AC circuit. It will
not work using an earthed wire or neutral point. If there are
several lines, such as 2-phase wires and 3-phase wires, per-
form voltage detection on each line separately.
• The 3120 cannot perform voltage detection on a shielded wire.
• Be sure to grip the 3120 firmly during measurement. But, do
not touch the portion beyond the barrier. It will not produce
any detection.
• Make sure the detecting element properly contacts the object
to be measured. (See the right figure.)
Detecting
element
×○
Barrier
Position the detecthing element
so that it is parallel to the object.
Voltage detection is not
performed properly.
3120 VOLTAGE DETEC-
TOR Object to be Measured
The red LED lights up and the
buzzer sounds. Live.
Only the green LED lights up. Not live or below the measurement-voltage
range (70 V or less).
The red LED does not light up
or the buzzer does not sound.
The red LED and buzzer
sound are getting off.
The red LED lights up
and the buzzer sounds.
OK NG
3. Grip the 3120 firmly and apply the
detecting element to a known power
supply
(e.g., AC outlet) in order to check the
performance.
The object cannot perform voltage
detection. (It is not live or the earth
potential is below the measurement-
voltage range (70 V or less).)
The batteries are running
The 3120 is operating
The 3120 may be malfunctioning.
properly. It can be used.
Do not use it.
The object is live.
low. Replace the batteries.
NG
OK
2. Turn the switch ON.
(Turn it clockwise.)
The green LED lights up. The green LED does not light up or is dim.
Switch
NG
The batteries are running
low. Replace the batteries.
The red LED lights up and the buzzer sounds.
Detection
The green LED is still lighting up.
Turn on the switch. In the state that the green
LED is lighting up, apply the detecting element
to the object to be measured. If there are sever-
al wires, conduct a voltage check of each wire
separately.
(Check some points for bundle of wires.)
Performance Check
1. Inspect the 3120 carefully to ensure that no damage.
There is no damage. The 3120 is damaged.
Be sure to check the following before use to avoid electrical
Contact your dealer or Hioki representative.
OK NG
shock.
