Commercial Vehicle Product Datasheet
Switch Diagrams
Switch Reference Guide - SPST, SPDT, DPST, DPDT
SP and DP refer to single pole and double pole, ST and DT refer to single throw and Double throw.
SP: Single Pole, one circuit controlled by the switch.
DP: Double Pole two independent circuits controlled by the switch which are mechanically linked.
Note: “Pole” should not be confused with “Terminal”. The DPST switch, for example has four terminals however is a Double Pole
(DP) and not a four pole (4P) switch.
ST: Single Throw, closes a circuit at only one position. The center position is off.
DT: Double Throw, closes a circuit in the up or down position (On-On). A Double Throw switch can also have a center position
such as On-Off-On.
The following switch diagrams illustrate the most common types of toggle and rocker switch.
SPST On-Off
DPST On-Off
Both load terminals can be energized at the same time. They are independent of each other and could be of
different voltages.
SPDT On-On
Only one of the loads can be energized at a time.
DPDT On-On
Functions like two separate SPDT switches operated by the same actuator. Only two loads can be On at a
time.
SPDT On-Off-On
Only one of the loads can be energized at a time.
DPDT On-Off-On
Functions like two separate SPDT switches operated by the same actuator. Only two loads can be On at a
time.
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© 2016 Littelfuse Commercial Vehicle Products
Rev: 082616
Commercial Vehicle Product Datasheet
Switch Diagrams
Single-Pole (SP) & Double-Pole (DP) Switch Wiring Diagrams
Diagrams represent both momentary contact or maintained contact switches.
Switches without Pilot Lights
SPST Off-ON (2 terminals)
SPDT On-Off-On (3 terminals)
DPST Off-On (4 terminals)
DPDT On-On (6 terminals)
DPDT On-Off-On (6 terminals)
Diagram A
Diagram B
Diagram C
Diagram D
Diagram E
4
B
+
L1
2
B
3
L
+
+
2
L2
Diagram A1
B
1
3
L1
B
+
L1
–
1
2
5
3
6
+
L2
B
B
+
L2
Diagram C1
B
+
1
+
4
3
L
3
4
2
5
3
6
+
L3
L1
B
B
L4
L2
+
1
4
2
5
3
6
–
–
–
–
L3
+
B
L4
B
–
L
1
L
6
Switches with One Pilot Light
SPST Off-ON – Dependent Illumination (Three terminals)
SPST Off-On – Independent Illumination (Four terminals)
SPST Off-On – Independent converted to Dependent (4 terminals)
To convert, connect jumper wire from terminal 3 to terminal 6 and
connect terminal 4 to ground
Diagram F
Diagram G1
Diagram G2
4
B
+
2
B
3
L
4
4
+
2
L
3
B
6
+
2
3
L
6
Jumper
Switches with Two Pilot Lights
SPST Off-On Dependent & Independent (Four terminals)
SPDT On-Off-On of On-On dependent (Four terminals)
SPDT On-Off-On or On-On Independent (Four terminals)
Diagram H
Diagram J
Diagram K
4
B
+
L
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B
2
3
6
1
L1
L2
+
2
3
2 of 2
4
L1
B
L2
+
1
4
2
5
3
6
© 2016 Littelfuse Commercial Vehicle Products
Rev: 082616