A selector switch, a pushbutton, and a pilot light are three distinct control-device families that routinely share the same panel cut-out and the same 22 mm or 30.5 mm mounting hole, which is exactly why specifying engineers confuse their roles on first-pass panel layouts [S4]. The three families differ in their electrical contact logic (maintained vs momentary), in their visible front-of-panel state (a switch position, a button cap, or an illuminated dome), and in their compliance scope (general industrial IP65 vs ATEX/IECEx for hazardous areas) [S1][S2].
Current IDEC, Werner Electric, Eaton, and OMEGA pilot-device catalogues all group these three products under the same "30 mm pilot devices" or "22.5 mm command & signalling" umbrella, with shared accessories such as contact blocks, transformer blocks, and legend plates, but with different operator heads, different contact configurations, and different electrical ratings per operator type [S3][S4]. This article lays out the spec bands, the standards, and the selection logic a process or panel engineer needs to pick the right device for each control function.
Definition and Functional Scope of the Three Device Families
Per IDEC and OMEGA pilot-device documentation, a selector switch is a manually operated control switch with two or more maintained positions (typically 2-, 3-, or 4-position) whose knob or lever stays in the position the operator last moved it to, driving a different contact combination at each detent [S4]. A pushbutton, by contrast, is a momentary operator: spring-return on the standard version, with a contact block that closes (N/O) or opens (N/C) only while the operator is actively pressing the cap, and returns to its normal state when the operator releases [S3].
A pilot light is not a switching device at all: it is an indicating light with a single lamp block (typically LED, 24 V AC/DC, 120 V AC, or 240 V AC variants) and no electrical contacts, used purely to show the state of a process or machine [S2][S4]. IDEC and Werner lines list illuminated selector switches and illuminated pushbuttons as separate SKUs, but the illumination is added by inserting an LED lamp block into a selector or pushbutton operator — the underlying switching function is unchanged [S1][S2].
Mounting Standards, Cut-Out Sizes, and IP Ratings Across the Three Families
OMEGA's E34 series and equivalent Eaton M22 / Cutler-Hammer 10250T lines all use the 30.5 mm (1-13/64 in) round panel cut-out as the North American default for heavy-industry pilot devices, while IDEC's HW and EU2B series and Werner's 40 series use the 22.5 mm metric cut-out as the IEC default [S3][S4]. Both cut-out sizes are documented as compatible with the same contact-block depth (roughly 50-60 mm behind the panel) and the same finger-safe terminal screws, so the choice between 22 mm and 30 mm is mechanical and aesthetic, not electrical [S1][S4].
Ingress protection differs sharply across the three families within the same series: Werner's 40-series selector switch is rated IP65 at the front-of-panel (dust-tight, jet-proof) for the standard knob, with an IP40 option for the compact body, and the matching pushbutton and pilot light in the same Werner line inherit the same IP65 front rating [S2]. For hazardous-area applications, IDEC's EU2B series extends the standard 22 mm operator to ATEX-certified emergency-stop, key-lock, and selector versions with the certification printed on the nameplate — the IP65 front rating is preserved, and the ATEX marking covers the operator-and-contact-block assembly as a unit, not the operator head alone [S1].
Contact Logic, Electrical Ratings, and Operator Types
Selector switches ship in maintained (latching) form as the catalogue default, with spring-return-from-left and spring-return-from-right variants available for momentary operations, and contact blocks typically rated 600 V AC / 10 A continuous (UL/CSA) or 250 V / 5 A (IEC) depending on the series [S2][S4]. A 2-position maintained selector wired with one N/O + one N/C contact block gives a binary "Run/Stop" or "On/Off" logic; a 3-position maintained selector with two N/O contact blocks gives the classic "Hand/Off/Auto" (HOA) logic used on motor starters and pump control panels [S4].
Pushbuttons ship in two electrical modes: momentary (spring-return, the default) and maintained (push-on/push-off, a separate SKU with a latching mechanism inside the operator body). Contact blocks are interchangeable between pushbutton and selector operators within a given series, which is why IDEC, Eaton, and OMEGA all sell "contact blocks" and "lamp blocks" as separate line items from the operator heads [S3][S4]. Pilot lights carry no electrical contacts — they only accept a single lamp block (LED 6 V, 12 V, 24 V, 120 V, 240 V, or a universal 24 V AC/DC variant) and the front lens colour (red, green, amber, blue, white) is a separate orderable part [S2].
Illuminated Operators and the Shared Lamp-Block Architecture
Werner's 40-series and Reny Electric's parallel line both market "LED-illuminated selector switches" and "illuminated push buttons" as standard catalogue SKUs, with green, red, white, and blue LED colours listed in the product characteristics [S2][S5]. The illumination is added by inserting a full-voltage or transformer-type LED lamp block into the centre of a selector or pushbutton operator — the same lamp block that would otherwise drive a standalone pilot light [S2][S4].
This shared lamp-block architecture is the technical reason a panel builder can specify one LED voltage (typically 24 V AC/DC for control panels fed from a 24 VDC PSU, or 120 V AC for North American motor-control centres) and use it across all three device families on the same panel, cutting the lamp-block SKU count by roughly two-thirds [S2][S4]. The trade-off is that a faulty LED lamp block takes down the indication on every device it is installed in, so spares policy and lamp-life ratings (typically 50,000-100,000 hours for industrial LED blocks) become a panel-engineering decision, not just a purchasing one [S2].
Hazardous-Area Compliance: When a Selector or Pushbutton Steps Outside IP65
IDEC's EU2B series carries an ATEX marking on the operator nameplate, covering emergency-stop, key-lock, and selector variants in the same 22 mm body [S1]. This is the only path the three device families have into Zone 1 / Zone 2 (gas) or Zone 21 / Zone 22 (dust) hazardous areas, and it requires the matching ATEX-certified contact blocks and lamp blocks to be fitted at the factory — field-substitution of non-ATEX contact blocks into an ATEX operator voids the marking [S1].
For a panel inside a non-hazardous industrial area, a standard IP65 selector, pushbutton, or pilot light from the Werner 40 series, the Eaton M22 line, or the OMEGA E34 line is the default specification, and the emergency light or explosion-proof light categories do not apply to the panel itself [S2][S3][S4]. A useful companion read is the pushbutton and pilot light vs emergency stop button spec-band breakdown, which lays out the contact-logic and colour-coding differences between a normal-state pushbutton and a certified E-stop mushroom-head in the same 22 mm and 30.5 mm form factors.
Criteria-Based Comparison: Selector vs Pushbutton vs Pilot Light
On four decision criteria the three device families line up as follows, per the IDEC, Werner, Eaton, and OMEGA product data [S1][S2][S3][S4]: (1) Output type — selector gives maintained multi-position switching, pushbutton gives momentary switching, pilot light gives no switching output (indication only). (2) Operator state visible on the panel — selector shows the knob/lever position, pushbutton shows the cap height (flush, extended, mushroom), pilot light shows the lens colour and on/off state. (3) Typical electrical rating per contact — 600 V AC / 10 A (UL) or 250 V / 5 A (IEC) for the switching families, no contact rating for the pilot light. (4) Lamp-block compatibility — pilot light always carries a lamp block, selector and pushbutton carry a lamp block only on the "illuminated" SKU variant.
Engineers should pick a selector when the panel needs a maintained mode change (HOA, Local/Remote, Manual/Auto), a pushbutton when the panel needs a momentary command (Start, Stop, Reset, Jog), and a pilot light when the panel needs remote indication of a process state (Run, Fault, Power On) without any switching action [S1][S2][S4]. Mixing the three in a single 22 mm or 30.5 mm cut-out is the standard pattern, with the shared contact-block and lamp-block architecture keeping the BOM and the spare-parts list compact [S1][S2][S3][S4].
Sourcing, Standards, and Trackable 2026 Signals
Standards governing the three device families include IEC 60947-5-1 (low-voltage switchgear, control-circuit devices, electromechanical control switches including pushbuttons and selector switches), IEC 60947-5-5 (control-circuit devices — emergency-stop devices with mechanical latching function), and the ATEX 2014/34/EU directive plus the IEC 60079 series for hazardous-area variants of the same 22 mm and 30.5 mm operator families [S1][S4]. The Werner 40 series, IDEC HW/EU2B, Eaton M22, and OMEGA E34 are all third-party-certified to these standards, with the certification marking printed on the product nameplate or referenced in the catalogue [S1][S2][S3][S4].
Two trackable signals for 2026 panel-engineering sourcing: (1) Reny Electric and other Asian OEM lines now publish a combined "illuminated pushbutton / illuminated selector / pilot light" family under one catalogue number series, which is a useful shorthand for buyers consolidating SKUs across all three functions [S5]. (2) The Cutler-Hammer / Eaton 10250T-style 30.5 mm legacy SKUs and IDEC / Werner's 22 mm metric SKUs both remain in active distribution on the surplus market alongside the current production lines, which is relevant for spare-parts continuity on panels older than roughly 2010 [S6].