DIN Rail Symbol
Definition: The DIN Rail symbol represents the standardised metal mounting track—defined in IEC 60715 as the TS 35 (top-hat) profile measuring 35 mm wide—used in electrical control panels, distribution boards, and industrial enclosures to mechanically support and organise circuit breakers, terminal blocks, relays, and other rail-mount devices, depicted in panel-layout diagrams as a horizontal bar spanning the full width of the component row.
Also known as: TS35 rail, top-hat rail, omega rail, mounting rail, DIN 46277 rail, EN 60715 rail, 35 mm DIN rail.
What the DIN Rail symbol means
The DIN Rail symbol in a panel-layout or wiring diagram indicates a structural mounting element onto which all adjacent electrical and electronic components in that row are physically attached. The rail itself carries no operational current in the circuit; it is a mechanical backbone that establishes the positional layout of every device snapped or bolted to it.
In electrical drawings the DIN Rail symbol defines the horizontal axis along which components are enumerated from left (Left pin) to right (Right pin), and it serves as the reference line for dimensioning component positions, calculating available rail length, and populating the bill of materials with the correct rail cut length.
How to identify the DIN Rail symbol
The DIN Rail glyph is drawn as a bold horizontal line or narrow horizontal rectangle spanning the width of a component row, often with short perpendicular tick marks or a stylised cross-section profile at its ends suggesting the T or omega (Ω) cross-section of the physical rail. In panel-layout software the symbol may show component snap-slots along its length. The Left and Right pins mark the physical termination points of the rail segment. It is visually distinct from a bus bar (which is thicker and electrically energised) by its lighter weight and mechanical-only annotation context.
Function in a circuit
The DIN rail provides a standardised snap-in mounting surface for all TS 35-compatible electrical components. Components clip onto the rail's 35 mm-wide flanges using integrated spring clips or screw-fix brackets, allowing tool-less installation and removal. The rail distributes mechanical load across the panel back-plate, aligns all components at a uniform height for wiring accessibility, and—when used as a bare steel rail—provides a common chassis connection point if components are bonded to it through their mounting clips.
Standards: IEC vs ANSI
| IEC 60617 | IEC 60715 (formerly EN 50022) defines the TS 35 top-hat rail profile: 35 mm wide, available in 7.5 mm and 15 mm depth variants. The standard specifies material (steel, aluminium, or stainless steel), tolerances, and mechanical properties. IEC 60617 does not assign a dedicated electrical symbol because the DIN rail is a mechanical component. |
|---|---|
| ANSI/IEEE 315 | ANSI / NEMA do not define a specific schematic symbol for DIN rails. In North American panel drawings the DIN rail is specified as a mechanical BOM item referencing IEC 60715 dimensions. NEMA enclosure standards (NEMA 250) reference DIN rail mounting as an optional feature. |
| Key difference | IEC-based drawings (European practice) include the DIN rail as a graphical element in panel-layout sheets; North American drawings typically list the rail in the BOM only without a dedicated graphical symbol. Both practices converge on IEC 60715 for the physical profile. |
Terminals / pins
| Pin | Name |
|---|---|
| left | Left |
| right | Right |
Typical values
Standard TS 35 rail dimensions: 35 mm wide × 7.5 mm deep (light duty) or 35 mm × 15 mm deep (heavy duty). Standard commercial lengths: 1 m (cut to size on-site) or pre-cut to panel width. Material: 1.5 mm or 2.0 mm thick zinc-plated steel; aluminium and stainless-steel variants available. No voltage or current rating—purely mechanical.
Where the DIN Rail symbol is used
- Industrial motor control centres (MCCs) and PLC enclosures for mounting contactors, drives, and I/O modules
- Residential and commercial distribution boards (DB panels) supporting MCBs, RCDs, and surge protectors
- Building automation system (BAS) control panels holding relay modules, power supplies, and terminal blocks
- Railway signalling and rolling-stock control enclosures requiring vibration-resistant component mounting
- Laboratory and test equipment racks organising modular instruments and power supplies
- Machine control panels in manufacturing and food-processing industries where rapid component replacement is needed
- Smart home and home automation panels mounting DIN-rail-format smart breakers, energy meters, and gateways
Example
In a 3-phase motor control panel layout diagram, three horizontal DIN Rail symbols are stacked vertically within the enclosure outline; the top rail carries the main isolator and three-pole MCBs, the middle rail holds the contactor and overload relay, and the bottom rail supports a row of 10 terminal blocks. Each DIN Rail symbol spans 400 mm between its Left and Right pins, and a DIN Rail End Stop symbol is placed at each end of every rail row.
Key facts
- The DIN Rail (TS 35) is standardised in IEC 60715, defining a 35 mm-wide top-hat (omega) cross-section profile available in 7.5 mm and 15 mm depth; the original profile was defined in the German DIN 46277 standard.
- The DIN Rail symbol in panel-layout drawings has two mechanical terminals: Left and Right, representing the physical ends of the cut rail segment; it carries no electrical current and has no voltage or current rating.
- TS 35 rail accepts a vast ecosystem of snap-in components including MCBs, RCDs, contactors, relays, terminal blocks, power supplies, PLCs, and I/O modules from virtually all major manufacturers.
- DIN rails are available in steel (zinc-plated), aluminium, and stainless steel; aluminium rails are used where weight reduction or corrosion resistance is critical, but aluminium has lower tensile strength than steel.
- The rail cross-section profile is also informally called 'omega rail' or 'top-hat rail' due to its resemblance to an inverted hat shape when viewed in cross-section.
- DIN rails are cut to length on-site using a hacksaw, angle grinder, or dedicated rail cutter, and are mounted to panel back-plates using M5 or M6 screws through pre-punched holes at 25 mm or 50 mm pitch.
- IEC 60715 also defines the TS 32 (G-rail, 32 mm × 15 mm) profile, which is less common but used for legacy installations and certain terminal block families; TS 35 and TS 32 components are not interchangeable.
Frequently asked questions
What does the DIN rail symbol mean in a panel layout diagram?
The DIN Rail symbol in a panel-layout diagram represents the standardised TS 35 metal mounting track (IEC 60715) on which circuit breakers, terminal blocks, relays, and other components are physically installed. It is a mechanical reference element showing the position and length of each mounting rail row within the enclosure.
What does the DIN rail symbol look like?
The DIN Rail symbol is drawn as a bold horizontal line or narrow horizontal rectangle spanning the width of a component row, sometimes with short perpendicular tick marks at its ends suggesting the top-hat cross-section profile. In panel-layout software it may show individual component snap-positions along its length.
What is the IEC standard for DIN rails?
DIN rails are standardised in IEC 60715, which defines the TS 35 top-hat profile (35 mm × 7.5 mm or 35 mm × 15 mm) and the TS 32 G-rail profile. IEC 60715 specifies dimensions, tolerances, and material requirements. The original profile originated in German standard DIN 46277.
Does the DIN rail carry electrical current?
A standard DIN rail does not carry operational electrical current in the circuit—it is purely a mechanical mounting element. However, in some installations the steel rail is bonded to the protective earth (PE) conductor through equipment mounting clips, making it part of the panel's earthing system, but not a current-carrying conductor.
What is the difference between TS 35 and TS 32 DIN rails?
TS 35 (top-hat rail) is 35 mm wide and is the dominant modern standard used by the vast majority of components worldwide. TS 32 (G-rail) is 32 mm wide with a different cross-section and is used for legacy terminal block families and certain European installations. TS 35 and TS 32 components are physically incompatible and cannot be mounted on each other's rails.
How long is a standard DIN rail?
Standard commercial DIN rails are sold in 1-metre lengths and are cut to the required panel width on-site. Pre-cut lengths are also available from some suppliers. Cutting is done with a hacksaw, angle grinder, or dedicated rail cutter, and cut ends should be deburred before installation to prevent cable insulation damage.
What components can be mounted on a TS 35 DIN rail?
TS 35 DIN rails accept an extensive range of snap-in components including miniature circuit breakers (MCBs), residual current devices (RCDs), contactors, motor protection relays, terminal blocks, PLC modules, power supplies, energy meters, surge protection devices, and smart home modules—all from virtually all major electrical equipment manufacturers.
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