The Schneider Electric A9C1B120 is a programmable astronomic twilight switch with integrated time switch, part of the Acti9 iC+ range. It controls a single lighting or resistive load channel (1 NO/NC contact) rated at 20 A for AC-7A and AC-7B utilisation categories at 230 V AC +/- 20 %, 50 Hz. The 20 A maximum switching current covers both resistive (pf=1) and inductive (pf=0.6) loads, so it handles LED banks, incandescent, heaters, and motor loads up to 4600 W or VA depending on type.
For LED lighting specifically, it's rated 1200 W at 230 V AC; for resistive loads (heaters, incandescent) it goes to 4600 W. The 200,000-cycle electrical durability at full load (AC-7A, AC-7B, and LED lighting) means this switch is built for years of daily cycling in building control, not occasional manual use. Accuracy of +/- 0.25 s/day at 25 °C keeps the time schedule tight — no drift issues for weekly or astro programs. The 10-year power reserve on the lithium battery means the clock holds through a power loss without re-programming. The 18 mm width (2 DIN modules) and 68 mm depth fit standard TH35 DIN rail enclosures.
This is a building automation component — used in residential and commercial lighting control panels to switch outdoor or indoor lighting based on time schedule and/or astronomical sunrise/sunset times. It can also be controlled via push button, digital input, or a mobile app over Bluetooth 5.0. The holiday schedule, automatic summer/winter time changeover, and bank holiday exceptions make it practical for site-wide lighting automation without a central BMS.
Lifecycle status is 'current' — this is an active, in-production part from Schneider Electric. No PCN or obsolescence notice is in effect. The CE marking and compliance with IEC/EN 60669-2-1 cover European installation requirements.