Nest Protect query

[Skimpy Wan]

Having recently fitted a Nest Protect Smoke / Carbon Monoxide alarm in a hallway (no more than 3mtrs away from any headboards) I've become aware that the decide has a 85db alert tone. Isn't the minimum level for building regs 90db at the headboard of a bedroom?

 

[tazz]

For domestic BS states for smoke alarms it should be 75db....this was found to be impractical, so its amended to 85db outside every bedroom door.
CO detection is better monitored near to the source not in bedrooms, this gives earlier warning of CO production.

 

[telectrix]

"Most fire detection and fire alarm systems in dwellings comprise smoke alarms, which are usually fitted in,
at least, the circulation areas, such as hallways and landings. BS 5446-1:2000 requires that the sound
output of a smoke alarm be at least 85 dB(A) at three metres. Most domestic doors attenuate sound by
around 20 dB; greater attenuation can occur in the case of solid doors, such as fire doors. It is therefore
unlikely that a smoke alarm on, for example, the upstairs landing of a two-storey house will produce a sound
level of 75 dB(A) at the bedhead in each bedroom, particularly if the bedroom doors are shut; levels of 55
dB(A) to 65 dB(A) are more likely. There appears to be no evidence to show that lives are being lost due to
inadequate audibility of the fire alarm signal from smoke alarms, except where people are incapacitated to
such a degree that even much higher sound levels would not waken them".

the above is for a smoke alarm.

 

[Skimpy Wan]

Oh okay. I guess the 90db is the same a hammer length for spacing between clips ... on site rule?

 

[tazz]

There is no site rule for 90db, approved document B and amended BS5839 both state 85db for domestic. Rule of 75db at the bedhead, still applies for Part 1 commercial eg Hotels, Hostels, Nursing homes etc.