A DPDT switch is a double pole, double throw device whose two independent changeover circuits move together in one movement, driven by a shared mechanism rather than a shared conductor. The standard package has six terminals in two rows of three, with a common in each row on most conventional layouts. Catalogues also write the configuration as 2P2T or DP2T. Swiclick builds this arrangement in the MSS, MSK, SK and SS slide switch series and in the PB series latching pushbuttons in bodies from 5.8mm square. Published DC switching ratings on the slide bodies run around 50V at 0.5A down to 30V at 0.2A depending on series, so this is a signal-level configuration rather than a power one. Catalogue naming varies between series, so confirm the terminal layout from the contact diagram rather than from the configuration code.
Six Terminals, Two Independent Circuits
Split the six terminals into two rows of three and each row is a complete SPDT switch.
Each row has its own common and its own two throws. The two poles have no intentional conductive connection in the contact diagram, and that separation is the entire reason the configuration exists.
Ganged means the two poles are driven by one mechanism. It does not mean they switch at exactly the same instant. Contact timing between poles is not perfectly matched, and the skew is a real number in fast circuits even though it rarely appears on a datasheet.
Terminal numbering varies between manufacturers and between series. On most conventional two-row bodies the middle terminal in each row is that pole’s common, but read the contact diagram rather than inferring it from the footprint drawing.
How Separate the Two Poles Really Are
Topologically the two circuits are independent. Electrically the separation has a limit that the contact diagram does not show.
The allowable voltage difference between the poles depends on the specific part’s dielectric strength, creepage and clearance dimensions. A body designed for signal-level PCB switching is not designed to hold off mains potential between its poles.
Nothing about a DPDT contact arrangement makes it an approved safety isolation barrier. If your two circuits sit at meaningfully different potentials, check the dimension and the dielectric rating in the datasheet rather than assuming the plastic between them is sufficient.
What You Can Do With Two Poles
Four patterns cover most of the real uses.
Switching a signal and its return together. Where the return is not board ground, opening only the signal line leaves a path through the return. Both sides have to move.
Selecting between two isolated sources. Two supplies, two returns, one selector. This is the case where shorting behaviour matters most, because a make-before-break part will connect the two sources during every transition.
Switching a load while flagging the state. One pole carries the working circuit, the other tells a controller which position the switch is in. This is more reliable than reading the load side.
Reversing polarity. Cross-connect the throws so the common pair sees the supply in one orientation on one side and the opposite on the other. This is the pattern used to reverse a small DC load.
The Reversing Pattern and Its Limit
The polarity reversing wiring is well known and easy to get wrong in one specific way.
Wire the supply to the two commons. Wire throw 1 of pole A and throw 2 of pole B to one side of the load, and throw 2 of pole A with throw 1 of pole B to the other side. Flipping the switch swaps which supply rail reaches which side of the load.
The limit is the rating, not the wiring. A DC motor is an inductive load and its stall current is far above its running current. Slide switch bodies in this class carry published DC ratings in tenths of an amp, which restricts direct reversing to very small loads. For anything larger, use the switch to drive a relay or an H-bridge and keep the motor current off the contacts.
Across the Product Families
Slide switches (MSS, MSK, SK, SS). The main DPDT population. Surface mount and through hole, horizontal, right angle and side actuation, bodies from small PCB sizes up to panel mount. The DPDT slide switch page covers formats, pinouts and shorting behaviour in detail.
Latching pushbuttons (PB series). Several PB-series parts use a six-terminal DPDT arrangement in bodies from 5.8mm square. These hold state mechanically, which suits a selector that has to survive a battery change. The latching push button switch page covers the mechanism and the part number trap that goes with it.
Micro switches. Swiclick’s G series is single pole. A double pole result in a snap-action format usually means two switch bodies actuated by one lever rather than one part.
Manufacturer-specific note: ratings, contact forms and terminal layouts quoted on this page apply only to the identified Swiclick models and must be verified against the exact datasheet.
Where the Second Pole Earns Its Place
Many designs specifying DPDT need only one pole, and the second is bought out of habit.
Ask one question: is there a second circuit that must move at the same time and must stay electrically separate from the first? If the answer is no, an SPDT switch in the same body style costs less and takes three fewer pads.
There is a defensible exception. Keeping a spare pole for a future revision is reasonable when the product roadmap is real. Write it into the schematic notes as a deliberate choice rather than leaving it as an accident. Deciding between SPDT and DPDT properly is worth a few minutes at BOM freeze.
Specifying One
- Poles and throws notation, and whether a centre position is needed
- Shorting or non-shorting, if the two throws are separate sources
- Momentary or maintained
- Load type, current and voltage on each pole, including whether it is DC
- Voltage difference between the two poles, if they are not at similar potential
- Terminal style, mounting method and actuator geometry
- Annual volume
Requirements and rating rules for mechanical switches of this class sit in IEC 61058-1-1. Standard parts in this configuration are normally quoted from a 500-piece minimum order quantity. Sample availability and preparation time depend on the specific part number and current stock, so confirm both at quotation.
FAQ
Double pole double throw. Two independent circuits, each moving between two destinations, driven by one actuator. Six terminals in the usual package.
Yes. 2P2T and DP2T are the same configuration written in the pole and throw numbering style. Terminal numbering still has to be read from the datasheet.
The wiring pattern works. Check the published DC rating first, because parts in this class are commonly rated in tenths of an amp. For anything beyond a very small load, drive a relay or an H-bridge instead.
They are galvanically isolated for normal low-frequency switching, with no intentional conductive connection between them. That is not automatically approval as a safety isolation barrier, and the allowable voltage difference depends on the part’s dielectric, creepage and clearance ratings.
Yes, and it is common. Keep the unused pads on the board and note the choice in the schematic so a later reviewer does not remove them.
The G series micro switch range is single pole. A double pole result in a snap-action format normally means two bodies driven by one lever.
