Precautions for All Relays
Refer to the Safety Precautions section for each Relay for specific precautions applicable to that Relay.
■ Precautions for Safe Use
These precautions are required to ensure safe operation.
• Do not touch the charged Relay terminal area or the charged 
socket terminal area while the power is turned ON. Doing so may 
result in electric shock.
• Do not use a Relay for a load that exceeds the Relay's switching 
capacity or other contact ratings. Doing so will reduce the specified 
performance, causing insulation failure, contact welding, and 
contact failure, and the Relay itself may be damaged or burnt. 
• Do not drop or disassemble Relays. Doing so may reduce Relay 
characteristics and may result in damage, electric shock, or 
burning.
• Relay durability depends greatly on the switching conditions. 
Confirm operation under the actual conditions in which the Relay 
will be used. Make sure the number of switching operations is 
within the permissible range. If a Relay is used after performance 
has deteriorated, it may result in insulation failure between circuits 
and burning of the Relay itself.
• Do not apply overvoltages or incorrect voltages to coils, or 
incorrectly wire the terminals. Doing so may prevent the Relay from 
functioning properly, may affect external circuits connected to the 
Relay, and may cause the Relay itself to be damaged or burnt.
• Do not use Relays where flammable gases or explosive gases may 
be present. Doing so may cause combustion or explosion due to 
Relay heating or arcing during switching.
• Perform wiring and soldering operations correctly and according to 
the instructions contained in Precautions for Correct Use given 
below. If a Relay is used with faulty wiring or soldering, it may 
cause burning due to abnormal heating when the power is turned 
ON.
■ Precautions for Correct Use
Contents
No. Area No. Classification No. Item Page
A Using Relays
C-3
B Selecting 
Rela
ys
A Mounting 
S
tructure and 
Type of 
Protection
1
2
3
Type of Protection
Combining Relays and Sockets
Using Relays in Atmospheres Subject to Dust
C-4
B Drive Circuits 1
2
Providing Power Continuously for Long Periods 
Operation Checks for Inspection and Maintenance
C-4
C Loads 1
2
Contact Ratings
Using Relays with a Microload
C-4
C Circuit 
Design
A Load Circuits 1
2
3
4
5
6
7
8
9
10
11
Load Switching
 A Resistive Loads and Inductive Loads
 B Switching Voltage
 C Switching Current
Electrical Durability 
Failure Rates 
Contact Protection Circuits 
Countermeasures for Surge from External Circuits 
Connecting Loads for Multi-pole Relays 
Motor Forward/Reverse Switching
Power Supply Double Break with Multi-pole Relays 
Short-circuiting Due to Arcing between NO and NC Contacts in SPDT Relays
Using SPST-NO/SPST-NC Contact Relays as an SPDT Relay 
Connecting Loads of Differing Capacities
C-5
B Input Circuits 1
2
3
4
5
6
7
8
9
10
11
12
13
Maximum Allowable Voltage 
Voltage Applied to Coils 
Changes in Must-operate Voltage Due to Coil Temperature 
Applied Voltage Waveform for Input Voltage 
Preventing Surges when the Coil Is Turned OFF 
Leakage Current to Relay Coils 
Using with Infrequent Switching 
Configuring Sequence Circuits 
Connecting Relay Grounds 
Individual Specifications for Must-operate/release Voltages and Operate/Release Times 
Using DC-operated Relays, (1) Input Power Supply Ripple
Using DC-operated Relays, (2) Coil Polarity
Using DC-operated Relays, (3) Coil Voltage Insufficiency
C-7
C Mounting 
Design
1
2
3
4
Lead Wire Diameters
When Sockets are Used 
Mounting Direction 
When Devices Such as Microcomputers are in Proximity
C-9
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C-2
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