On a micro switch, a rating such as 16(6)A 250V~ carries two current limits: 16 A is the resistive load rating, and the (6) A in parentheses is the inductive load rating, the maximum motor or coil current the contacts are tested to break at that voltage. The inductive number is always lower because switching motors, solenoids, and coils draws inrush on make and arcs on break; inrush can reach about six times the rated current (Crouzet), so a switch that holds 16 A resistive can weld at a fraction of that under a motor. Each figure is tested separately under defined UL or IEC conditions, so when two parts differ only in the parenthetical, 16(6)A versus 16(4)A, the safe figure is the one that matches your real load, not the larger headline number.
Swiclick builds the G-series snap-action micro switches this applies to, including the G20 rated to 16 A @ 125/250VAC, with the rest of its agency rating codes stated on the datasheet. The decision rule for substituting across inductive ratings follows.
What the number in parentheses actually is
A full electrical code rating packs several facts into a short string. Read 16(6)A 250V~ T85 left to right:
- 16: resistive (non-inductive) load amperage.
- (6): inductive load amperage at the same voltage. Some agencies print this as a separate “H” or “non-inductive” line instead.
- A: amperage. 250V: rated voltage. ~: AC.
- T85: maximum operating temperature, 85 °C.
- µ: micro-gap construction, a contact gap under 3 mm.
So 16(6)A and 16(4)A share the same 16 A resistive ceiling and differ only where it matters for a coil or motor: one is rated to break 6 A of inductive load, the other 4 A. Other codes on the part (a UL HP figure, a temperature class, an “L” lamp rating) follow the same rule: each is a separate test, so read it on the datasheet rather than inferring it from the headline amps.
Why the inductive number is always lower
Resistive loads such as heaters and ovens draw steady current and break cleanly. Inductive loads fight the switch. On make, a motor or solenoid pulls inrush up to roughly 6× the rated value (Crouzet); on break, the collapsing magnetic field sustains an arc that erodes and can weld the contacts. DC is worse, because the current never crosses zero to help quench the arc.
That is the whole reason agencies publish two figures. The resistive rating is the metal’s steady-state ceiling. The inductive rating is what the contacts survive when the load resists being switched. Size to the resistive number alone and you have rated the switch for the easy case while the application runs the hard one.
Derating at a glance: same switch, different loads
A single contact rating changes with load type and voltage. Industry derating multipliers (NKK) give a working estimate from a resistive AC rating:
| Load type | Multiplier vs. resistive (≈) |
| Resistive | 1.0 |
| Inductive (PF 0.6) | 0.5 – 0.66 |
| Motor | ~0.33 |
| Capacitive | ~0.25 |
| Lamp (tungsten inrush) | 0.2 – 0.25 |
These are estimates, not approvals. A 16 A resistive switch lands near 5 A on a motor load by this math, which is why the same basic switch can carry a 16 A headline and a single-digit inductive figure. Use a published rating for your load type when one exists; use the multiplier only to sanity-check a substitution before you order samples.
“Can I replace a 16(6)A switch with a 16(4)A one?”
This is the exact case an engineer raised on DigiKey’s TechForum: an original part rated 16(6)A 250VAC, the closest mechanical match a Honeywell V15T16 rated 16(4)A. The honest answer is a four-step check, in order:
- Match the mechanical fit first. Mounting holes, actuator, lever length, and operating force decide whether the part installs at all. Most failed cross-references die here, not on the rating.
- Identify your actual load. If the circuit is resistive (or inductive but drawing under 4 A), the 16(4)A part covers it, and the lower parenthetical does not affect you.
- Refuse the gap only when your load lives in it. If the real inductive load sits between 4 A and 6 A, the 16(4)A switch is under-rated for the job and the substitution is unsafe, regardless of the matching 16 A resistive figure.
- When unsure, choose equal-or-greater under the same test conditions: same voltage, same load type, same agency standard. A bigger number tested under different conditions is a different test, not a larger margin.
The part most compatibility pages skip: a rating is only as trustworthy as the conditions behind it. Two switches can both read 16 A and live very different lives, because one was tested at a higher temperature, a different cycle rate, or a different power factor. Anyone promising a blanket drop-in across brands without reading both datasheets is selling optimism. The parenthetical, the temperature code, and the standard are the substitution; the amp number in front of them is not.
How Swiclick rates its micro switches
Swiclick builds snap-action micro switches in the G series: G10 ultra-miniature, G15 at 6 A and 10 A, and G20 rated to 16 A @ 125/250VAC. The G20 datasheet also carries a coded agency rating (printed as 25T125) for a defined load condition. That code is this whole page in miniature: the bare number means nothing without the test condition behind it, so read it on the datasheet rather than inferring it. Contacts come in SPST (NO/NC) and SPDT; terminals in PCB, solder, quick-connect, and 90° bend-foot. The G series is certified to UL (component recognition for switches), ENEC (ENEC-01613), and TÜV Rheinland, under an ISO 9001 quality system.
A headline amp number is the start of a sizing decision, not the end of it. Send the part number you are replacing and the real load it switches, and an application engineer will confirm the right contact rating for your conditions against the datasheet before you commit a board.
FAQ
It is the inductive load rating: the switch is rated to break 4 A of inductive load (motors, solenoids, relay coils) at the stated voltage, versus 16 A of resistive load. Match the figure to your actual load type.
No. A larger resistive number tested under different conditions — temperature, cycle rate, power factor, AC versus DC — is a different test, not a guaranteed bigger margin. Compare the rating that matches your load and the standard behind it.
Resistive loads draw steady current and break cleanly. Inductive loads pull inrush on make and arc on break, so their rating is lower — typically half to two-thirds of the resistive figure at the same voltage.
Only with heavy derating. DC current does not cross zero, so arcs persist far longer. A common rule sizes DC inductive capacity at a small fraction of the AC resistive rating; confirm against the datasheet, never assume parity.
Codes like this are agency ratings tied to a specific tested load condition, not a plain amp figure. Treat them the same way as the inductive parenthetical: the number means nothing without the condition behind it, so read the exact definition on the part’s datasheet rather than inferring it.
The certification covers the ratings as tested and printed on the part and datasheet, each under its own defined conditions. Read both figures on the certified datasheet; a mark alone does not tell you the inductive number.
