Wash. Rev. Code § 4.24.785
(1) Any fire protection service agency, as defined in RCW 52.12.160, as well as the firefighters therein, whether volunteer or paid, that delivers to, or installs at, residential premises a device or batteries for such a device is not liable for civil damages resulting from any act or omission in the delivery or installation of a device or batteries for such a device, provided:
[ 2020 c 149 s 1.]