On 30/11/2019 09:15, ARW wrote:
45% due to bad positioning, 20% no battery. So why did the rest fail?

https://www.bbc.co.uk/news/uk-england-50598387

How badly does it need to be positioned to cause it not to work?

If the doors are closed it may not go off until the fire reaches the
room that it is in. Another only recently discovered problem is that
young children can sleep through a standard smoke alarm noise!

https://www.bbc.co.uk/news/health-38918056


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Regards,
Martin Brown