Short answer: a push button or pilot light is specified by four things, in this order — the contact block (1NO, 1NC, or a combination), the utilisation category (AC-15 for AC control circuits, DC-13 for DC), the lamp or LED module voltage for illuminated versions, and the front-of-panel protection and panel cut-out. The headline current on the datasheet is thermal current (Ith), not the current the contact can actually break. For the CHINT NP2 series, Ith is 10 A, but the AC-15 rating at 415 V is 1.9 A — and a DC coil at 24 V is a different question again.
This page explains how to read those numbers so the button you order matches the circuit it switches, and where the usual mistakes come from. We are an independent trading company — not a manufacturer and not an appointed distributor of any brand — so ratings here are quoted per exact ordering code.
The four ratings, and which one you quote
A control device datasheet is not one number. It is a stack of ratings for different questions, and mixing them up is how a 10 A button ends up welded shut on a 2 A contactor coil.
| Rating | What it answers | NP2 figure | How to use it |
|---|---|---|---|
| Ui — rated insulation voltage | What voltage the insulation system is designed for | 690 V | Circuit design and clearances. Not a switching claim. |
| Ue — rated operational voltage | The voltage at which the switching ratings below apply | AC 415 V / DC 250 V | Sets the ceiling for the utilisation categories. |
| Ith — conventional thermal current | Current the device carries continuously without excessive heating | 10 A | Busbar and wiring sizing, and whether the contact survives a stuck load. Not a making/breaking rating. |
| AC-15 / DC-13 | Making and breaking capacity for control circuits | AC-15: 1.9 A at 415 V | The number that actually decides whether the contact lives. Quote this one. |
So the honest statement is: the NP2 is a 10 A thermal device whose control-circuit switching capability is 1.9 A at 415 V AC in AC-15 duty. If the load is a 9 A contactor coil, this is the wrong device — you need a contactor auxiliary contact or an interposing relay, not a panel button.
AC-15 versus DC-13: the DC trap
Utilisation categories under IEC/EN 60947-5-1 describe the load, not the device. AC-15 covers switching AC electromagnets up to 72 VA; DC-13 covers DC electromagnets, and DC is the harder duty because there is no zero crossing to extinguish the arc. A contact that breaks 1.9 A of AC at 415 V will not break the same current at 220 V DC, and at 24 V DC the limit is set by the coil’s time constant, not by the current alone.
Practical consequences: an AC coil on a small contactor is fine in AC-15 duty, checked against sealed coil VA at your voltage. A DC coil at 24 V DC — now the default in most new panels — needs the DC-13 figure at 24 V, counting steady-state current and not inrush. Two coils on one button means adding the currents and derating, because the first contact to open takes the whole arc. A PLC input drawing 5–10 mA is the opposite problem: too little current to keep a power contact clean, so oxide builds, the input reads false, and the answer is a low-level (gold-flashed) contact block or an interface relay.
Colour and function: IEC 60073 is not decoration
The colour of the actuator carries meaning, and in a plant with more than one shift it is a safety feature rather than a preference. IEC 60073 assigns the general meaning; the machine builder assigns the specific action.
| Colour | Meaning | Typical use |
|---|---|---|
| Red | Emergency, stop, fault | Stop and emergency stop. On an emergency stop it must be a latching mushroom head with direct opening action — a standard momentary push button is not an emergency stop. |
| Green | Start, normal condition | Start, reset, “ready”. |
| Yellow | Abnormal, warning, intervene | Reset after a fault, attention required, return to a defined state. |
| Blue | Mandatory action | Resetting a mandatory function; not for stop. |
| White | General, no specific meaning | Start/stop where no colour convention is agreed, general purpose. |
| Black / grey | General | Common for start in older panels; avoid mixing conventions within one panel. |
Two rules that prevent real accidents: never use green for stop, and never use a red momentary button as an emergency stop. An emergency stop is specified under IEC 60947-5-5: latching, with direct opening action on the NC contact (the contact is pushed open by the actuator, not by a spring), yellow background behind the red actuator, and reset only by a deliberate action that does not restart the machine.
Illuminated versions: the lamp module is a separate code
A pilot light and an illuminated push button are two purchases inside one housing: the actuator plus contact block, and the lamp or LED module. Three things to get right:
- Module voltage must match the control circuit, not the main circuit. A 230 V LED module on a 24 V DC control circuit is a dark button; a 24 V module on 230 V is a destroyed module. Order the module voltage explicitly — it is a separate line on the order.
- AC versus DC modules are not always interchangeable. Many LED modules accept both, some do not; check the code’s voltage range rather than assuming.
- Current draw counts against the control transformer. Ten illuminated buttons at 20 mA is 200 mA of continuous load — small, but it belongs in the transformer sizing along with the coils and the relay holding currents.
For a pilot light the decision is colour plus lens type: a direct LED (long life, fixed colour) against a holder with a replaceable bulb. In a hot panel LED wins on life; where the stores department keeps spare bulbs, a replaceable holder still has a following. Either way the lens colour follows the same IEC 60073 table.
Panel fit: cut-out, protection and mounting
The mechanical side is where a cheap button becomes expensive. Confirm four details before ordering:
| Detail | Why it matters | What to confirm |
|---|---|---|
| Panel cut-out diameter | A 22.5 mm hole will not hold a 22 mm collar, and a punched hole cannot be un-punched | The exact cut-out in the series datasheet for the version you are buying |
| Front-of-panel IP | The IP claim is for the front face with the gasket correctly compressed | The IP figure for the exact version, plus the gasket supplied with it |
| Behind-panel depth | Contact blocks plus wiring need room behind a shallow door | Depth with the contact block fitted, and the bend radius of your wire |
| Contact block configuration | Adding a second block later may need a different mounting collar | Whether the version accepts extra blocks, and which ones |
A tight hole also damages the gasket, which is why a punched 22.5 mm hole with a burr is the most common cause of a “leaking” IP65 button. Deburr before mounting; the seal is doing the work, not the nut.
Where NP2 sits, and when to look elsewhere
Within the CHINT control range the NP2 series covers push buttons, pilot lights and selector switches to IEC/EN 60947-5-1: Ui 690 V, Ue AC 415 V / DC 250 V, Ith 10 A, AC-15 1.9 A at 415 V, with public KEMA certification. That is a sensible, well-documented device for machine control, small distribution boards and pump panels where the control circuit is an AC coil at 110–415 V.
It is not the right part in three situations: a direct-on-line starter switching a large coil on one contact, a DC control circuit at high current, and an emergency stop that must comply with IEC 60947-5-5. In the first two cases the fix is an interposing relay — the button switches the relay, the relay switches the coil — and in the third it is a purpose-built emergency stop device rather than a coloured button.
Because these items are cheap per piece and expensive per mistake, we quote them against the full code: series, actuator type and colour, contact configuration, lamp module voltage and legend text. Send the relevant section of the control schematic and we will read it back as a bill of materials before anything is packed — the same discipline applied to the contactors and overload relays they sit next to, in contactors and motor control and NR2 overload relay setting.
FAQ
Q: Is a 10 A push button safe to switch a 10 A load?
A: No. 10 A is the thermal current the device can carry. The switching capability is given by the utilisation category — for the NP2 that is AC-15 at 1.9 A and 415 V. Size the contact against AC-15 or DC-13, not against Ith.
Q: Can one button switch two contactor coils?
A: Only within the AC-15 rating at your voltage, and only with the currents added. Above a few amps of combined coil current, use the button to drive an interposing relay and let the relay contacts carry the coils.
Q: Why does my illuminated button glow faintly when the machine is off?
A: Usually leakage current through an electronic output or a long parallel cable run, or a neon module on a circuit with a capacitive coupling path. It is a wiring and module-type problem, not a faulty button; an LED module with a lower holding current, or a bleeder resistor, normally clears it.
Q: Can a standard red push button be used as an emergency stop?
A: No. An emergency stop needs latching operation and direct opening action on the NC contact under IEC 60947-5-5, plus a yellow background. A momentary red button is a stop button, and the difference matters in an accident investigation.
Q: Does the front IP rating cover the whole panel?
A: No. It covers the front face of that device with its gasket correctly seated. The panel’s own rating depends on the enclosure, the cut-outs and the sealing of every other entry — see IP rating and enclosure selection.
Q: What do I need to send for a quotation?
A: Series and actuator type, colour, contact configuration (1NO, 1NC or combination), whether illuminated and at what voltage, panel cut-out, IP required at the front, quantity, destination country and the control circuit voltage and frequency.
What to send us for a quotation
Actuator type and colour · contact configuration · lamp module voltage if illuminated · panel cut-out and front IP · quantity · destination country · control circuit (V / Hz / AC or DC) · legend text. You get unit price, packing data (pcs per carton, gross weight, CBM) and the certificate document for the exact ordering code. Request a quotation.
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