Key Switch Guide for Control Panels: Key-Retaining Positions, Contact Ratings and How to Read IEC 60947-5-1
TL;DR
A key switch is specified in two halves: the operator, meaning its positions, where the key can be removed and its IP rating, and the contact block, meaning its Ue, Ie and AC-15/DC-13 rating under IEC 60947-5-1. Get both halves right and the panel stays secure while the contacts survive the real load.
A key switch does two jobs on a control panel. It decides who is allowed to change a machine's state, and it switches a real control circuit when they do. Most specification mistakes come from treating it as one part when it is really two: a lockable operator on the front and a contact block behind it. This guide explains key-retaining positions, how to read contact ratings, and what IEC 60947-5-1 actually tells you on a datasheet, so the switch you order controls access properly and lasts.
What Is a Key Switch on a Control Panel?
A key switch, often called a key selector switch, is a rotary operator that can only be turned with the correct key. It is used for maintenance or setup modes, run enable, bypass access and any function that only authorised staff should change. Behind the panel, one or more contact blocks do the electrical switching.
These switches are everywhere in local equipment building. JTC reports that 20% of the world's semiconductor equipment is manufactured in Singapore, and much of that equipment carries operator panels where mode changes need controlled access.
What Do Key-Retaining Positions Mean?
A key-retaining position is one where the key cannot be withdrawn. Datasheets list the positions where the key can be removed, and the rest retain it. RAFI's RAFIX 16 keylock range, for example, is offered with key removal in position 0 only, in 0 and 1, or in 0, 1 and 2.
| Key removal positions | What it enforces | Typical use |
| 0 only | Key stays in the switch whenever it is turned away from 0 | Maintenance or setup mode that must not be left active |
| 0 and 1 | Either state can be locked in with the key removed | Enable or disable functions left in place by a supervisor |
| 0, 1 and 2 | Every position can be locked in | Three-way mode selection such as manual, off and auto |
Function matters as much as key removal. A latching switch holds its position, while a momentary one springs back when released, and our guide to momentary vs latching switches covers that choice. The RAFIX 16 F keylock switch we stock is latching with one 90° rotation, an IP65 front and a rated operating life of 65,000 cycles according to RAFI's datasheet.
How Do You Read IEC 60947-5-1 on a Key Switch Datasheet?
IEC 60947-5-1 is the standard that defines how the contacts of any control panel switch are rated and tested. Its published scope states that it "applies to control circuit devices and switching elements intended for controlling, signalling, interlocking, etc., of switchgear and controlgear," up to 1,000 V AC or 600 V DC (IEC 60947-5-1:2024 scope). On a datasheet, look for four values:
- Ue, rated operational voltage: the voltage at which a current rating applies.
- Ie, rated operational current: the current the contact can switch at that voltage and category.
- Ui, rated insulation voltage: the insulation limit, which Ue may never exceed.
- Ith, conventional thermal current: what the contact carries continuously without switching.
What Does an AC-15/DC-13 Rating Tell You?
It tells you what the contact can switch when the load is a coil, which is the hardest job in a control circuit. AC-15 covers the control of AC electromagnetic loads, such as contactor coils and solenoid valves, while DC-13 covers DC electromagnets, as summarised in Elesta's overview of utilization categories. DC is tougher because the arc does not self-extinguish, so DC ratings fall quickly as voltage rises. RAFI's datasheet for the RAFIX 16 silver contact block 1.20.122.001/0000 shows this clearly:
| Category | Rated voltage (Ue) | Rated current (Ie) |
| AC-15 | 250 V | 1.5 A |
| DC-13 | 24 V | 2 A |
| DC-13 | 60 V | 1 A |
| DC-13 | 125 V | 0.4 A |
| DC-13 | 250 V | 0.275 A |
Source: RAFI technical data sheet 1.20.122.001/0000; rated insulation voltage 250 V.
Read the AC-15/DC-13 rating at your actual coil voltage, not the headline figure. For low-level PLC inputs, a gold-contact block is the better fit, because silver contacts are designed for higher loads and can become unreliable at milliamp currents.
Mechanical Life vs Electrical Life: Which Number Matters?
Both, because whichever runs out first sets the service life. Mechanical life counts operations with no load, while electrical life counts operations at a stated load and is normally lower. The RAFIX 16 silver contact block is rated for 1,000,000 operating cycles, yet the keylock operator above is rated for 65,000. On a key switch the lock is usually the limit, which is fine for mode selection but a poor choice for a button pressed every cycle.
Do You Need Positive-Opening Contacts and What IP Rating?
Use positive-opening contacts whenever a normally closed contact forms part of a safety function. Positive opening means the actuator forces the contacts apart through a rigid link, even if they have welded. RAFI's datasheet for its RAFIX FS emergency stop element puts it simply: "The NC contacts of these switching elements are forcibly separated according to IEC 60947-5-1." Our article on emergency pushbutton wiring and contact blocks covers this in detail.
For sealing, check the front IP rating under IEC 60529. IP65 means dust-tight and protected against water jets, while IP54 means dust-protected and splash-resistant. In Singapore's humid plants and washdown areas, IP65 on the front face is a sensible default.
Specify the Operator and the Contact Block Together
Choose the key positions to match who should control the machine, then size the contact block to the real coil load and voltage. Specifying both halves together gives you a key switch that is secure on the front and dependable behind the panel.
Sisco Interconnect supplies RAFI control components, including keylock switches and contact blocks, from Singapore. Send us your positions, voltage and load, and we will help match the parts. Request a quotation.
Frequently Asked Questions
What is a key-retaining position on a key switch?
It is a position where the key cannot be removed, so the switch cannot be left in that state without the key in place.
What is the difference between AC-15 and DC-13?
AC-15 rates switching of AC electromagnetic loads such as contactor coils. DC-13 rates switching of DC electromagnets, which is harder on contacts.
Is a key selector switch covered by IEC 60947-5-1?
Yes. IEC 60947-5-1 covers control circuit devices and switching elements, which includes key-operated selectors and their contact blocks.
Why is the contact block rating lower at higher DC voltage?
A DC arc does not cross zero, so it is harder to break. Higher voltage sustains the arc longer, so the permitted current drops.
What IP rating should a control panel switch have?
IP65 on the front suits most industrial panels, especially in humid or washdown areas. IP54 suits drier, sheltered locations.
Related reading: Signal Lamp Guide: Choosing the Right Panel Indicator Light