It occupies a single modular width (18 mm), so it slots into a standard distribution board or control panel without crowding adjacent breakers or relays. There are no normally-open contacts on this variant.
The 20 A AC operational current is the continuous carry rating under AC load. That covers most lighting, resistive heater, and small motor contactor duties within the 250 V AC line-to-line or line-to-neutral envelope. The 1000 W incandescent lamp switching capacity gives a quick check for lighting-circuit replacement: if the lamp bank pulls under 1 kW, this contactor handles the inrush without welding the contacts. Power loss runs 1.7 W per pole in hot operating state. That is low enough that a single unit in a closed panel won't need derating, but the installation note explicitly calls for spacers between adjacent devices to ensure heat dissipation — so don't pack them tight without the recommended air gap. It belongs inside a panel or enclosure with a higher-rated door — not on a washdown line or outdoors without a cover.