The Siemens 3VA9278-0CK12 is a SENTRON Max-Flex remote operator kit — a Bowden wire actuator that lets you mount the breaker handle on an enclosure door while the breaker body stays inside, up to 0.9 m (36 inches) away. The kit is complete: steel handle with an epoxy sheath, the Bowden cable, and the switching mechanism that interfaces with the breaker. It is rated NEMA 1, 3R, and 12, meaning the handle assembly is suitable for indoor (NEMA 1), outdoor rainproof (NEMA 3R), and dust-tight / drip-tight industrial (NEMA 12) enclosures — a single handle that covers a range of panel environments without needing separate gasketed variants.
Compatible breakers and integration note
This kit is designed for Siemens 3VA5 250 A frames and 3VA6 150/250 A frames. The switching mechanism clips onto the breaker's rotary handle interface; the Bowden cable routes through a gland plate or knockout, and the steel handle mounts on the door. The 0.9 m cable length gives enough slack for a standard-depth enclosure with the breaker mounted on a back panel. If you are retrofitting an existing panel that was built around a 3VA5 or 3VA6, this kit drops in without rewiring — the breaker itself stays in place, and you add only the mechanical linkage.
What the NEMA ratings mean for deployment
NEMA 1 covers general-purpose indoor use where falling dirt and light splash are the concern. NEMA 3R adds rainproof and sleet-resistant construction — the handle assembly can live on an outdoor enclosure wall without weather damage. NEMA 12 is the industrial workhorse: dust-tight and drip-tight, so the handle survives washdowns and airborne particulates common in food processing, packaging, and machining lines. The epoxy sheath on the steel handle resists corrosion better than painted steel, which matters in NEMA 12 environments where cleaning chemicals are routine.