smoke detecters 25mm away from ceiling?

[Guest112]

just checking through my books and smokeys have to be between 25 and 600mm away from the ceiling does that mean i have to mount them on those round spacer boxes? seems a bit silly to me youd think smokeys would be designed to fit on the ceiling am i wrong about this or am i right about these smokey spacers?

TIA

 

[i=p/u]

600mm away from edges of wall

 

[mogga]

Im not up to things on alarm side bar the run of the mill stuff but if its 600mm from edge of walls ect how would i fit one in a cupboard used to store flamable stuff ??
or a db cupboard where its onlt 1200x600

 

[a1guvner]

Dont quote me on it but i do remeber seeing something mentioning a min detection from the ceiling ie the sensing chamber, had this query when some disabled hoists were going to possibly hit commercial smoke heads and we found a mention of this magic 25mm in BS5939

 

[i=p/u]

install it out side and leave cuboard doors open, and if need be put an obstacle in place

 

[Richard Burns]

Isn't a standard smoke alarm about 25mm+ deep and therefore the smoke entry point is more than 25mm from the ceiling?

 

[Guest112]

cheers guys im just going to mount them to the ceiling then seemed silly sitting them on a spacer box