A system, comprising: a water mist fire protection system; a deck, a raised floor disposed above the deck at no more than a maximum distance of 3.28 ft. (1.0 m) above the deck to define an interstitial space therebetween, at least one below-the-floor cable tray disposed between the floor and the deck at a distance of no less than 12 in. (30.48 cm) from the floor, and a ventilation system providing a flow of cooling air through the interstitial space, the water mist fire protection system comprising: a plurality of water mist nozzles disposed beneath the raised floor, each nozzle including a frame body having an inlet, an outlet with a passageway extending between the inlet and the outlet to define a nozzle axis, a discharge coefficient of a nominal K-Factor of less than 1.0 gpm/(psi) 1⁄2 (14.4 lpm/(bar) 1⁄2) and a working pressure, a seal assembly, a thermally responsive trigger to support the seal assembly in the outlet; and a diffuser coupled to the frame body and spaced from the outlet, the plurality of water mist nozzles are upright and have a nozzle-to-nozzle spacing ranging from a minimum 1.8m x 1.8m (6ft x 6ft) to 3.7m x 3.7m (12ft x 12ft), the diffuser being at a diffuser-to-floor distance of no more than a maximum of 75mm (3 in.) and spaced no more than 30.6cm (12 in.) from an elongated edge of at least one below-the-floor cable tray such that the nozzle is not directly above the at least one below-the-floor cable tray; and a network of pipes interconnecting the plurality of nozzles to a water supply for generating a water mist for effectively addressing a fire, the water mist effectively addresses the fire in the presence of any one of: (i) continuous flow of air through the interstitial space; (ii) fire-propagating cable in the cable tray; and (iii) a fluid delivery delay from the water supply to the water mist nozzles characterized in that: wherein the raised floor has a floor grate region, at least one of the nozzles disposed beneath the raised floor is installed beneath the floor grate region, the at least one nozzle being no further inset than a maximum 51mm (2 in.) from a lateral edge of the floor grate region. a water mist fire protection system; a deck, a raised floor disposed above the deck at no more than a maximum distance of 3.28 ft. (1.0 m) above the deck to define an interstitial space therebetween, at least one below-the-floor cable tray disposed between the floor and the deck at a distance of no less than 12 in. (30.48 cm) from the floor, and a ventilation system providing a flow of cooling air through the interstitial space, the water mist fire protection system comprising: a plurality of water mist nozzles disposed beneath the raised floor, each nozzle including a frame body having an inlet, an outlet with a passageway extending between the inlet and the outlet to define a nozzle axis, a discharge coefficient of a nominal K-Factor of less than 1.0 gpm/(psi) 1⁄2 (14.4 lpm/(bar) 1⁄2) and a working pressure, a seal assembly, a thermally responsive trigger to support the seal assembly in the outlet; and a diffuser coupled to the frame body and spaced from the outlet, the plurality of water mist nozzles are upright and have a nozzle-to-nozzle spacing ranging from a minimum 1.8m x 1.8m (6ft x 6ft) to 3.7m x 3.7m (12ft x 12ft), the diffuser being at a diffuser-to-floor distance of no more than a maximum of 75mm (3 in.) and spaced no more than 30.6cm (12 in.) from an elongated edge of at least one below-the-floor cable tray such that the nozzle is not directly above the at least one below-the-floor cable tray; and a network of pipes interconnecting the plurality of nozzles to a water supply for generating a water mist for effectively addressing a fire, the water mist effectively addresses the fire in the presence of any one of: (i) continuous flow of air through the interstitial space; (ii) fire-propagating cable in the cable tray; and (iii) a fluid delivery delay from the water supply to the water mist nozzles characterized in that: wherein the raised floor has a floor grate region, at least one of the nozzles disposed beneath the raised floor is installed beneath the floor grate region, the at least one nozzle being no further inset than a maximum 51mm (2 in.) from a lateral edge of the floor grate region. a network of pipes interconnecting the plurality of nozzles to a water supply for generating a water mist for effectively addressing a fire, the water mist effectively addresses the fire in the presence of any one of: (i) continuous flow of air through the interstitial space; (ii) fire-propagating cable in the cable tray; and (iii) a fluid delivery delay from the water supply to the water mist nozzles characterized in that: wherein the raised floor has a floor grate region, at least one of the nozzles disposed beneath the raised floor is installed beneath the floor grate region, the at least one nozzle being no further inset than a maximum 51mm (2 in.) from a lateral edge of the floor grate region.