Fail-Safe 10 : Locking an output device with the application of power and having the device unlock when the power is removed. Also known as fail unlock, reverse action or power locked
Solutions Fire Safety Ltd, Fire Safety Glossary: An A - Z of definitions regarding fire safety terms and vocabulary, Solutions Fire Safety Ltd, UK 2012. http://solutionsfire.co.uk/Fire-literatures-PDF/Fi re-Safety-Glossary.pdf, (Fr Sfty - Brit) {465}