Why do smoke detectors have to be wired in sequence?

[Ryland]

Why do they have to be wired in sequence instead of outwards from a central point? I.e:

In Sequence:
S - S - S

Not:
S
|
S - S -S
|
S

Since all reds need to be tied together I don't see why it matters. Can someone explain this?

Thanks.

 

[oleguy]

the red wires are the sence lead.when one goes off the all go off to alert you any where in the house.doesn't matter just so all red wires get tied together.

 

[Ryland]

The instructions I found via google always said they were in sequence so that only 2 wires were in each junction box.

 

[oleguy]

that is just the normal way to do it,not that it cannot be done other wise as they are in paralell and not series.

 

[Ryland]

Ok, thanks. The main reason Im asking is that I need to add smoke detectors to my 2nd floor due to an addition (and thus the fire marshall says I need to be brought up to code in the old part of the house. I currently have one at the top of the stairs (marked O) and need to wire new ones in the locations marked S. Realistically the space between O and S2 is only about 3 feet as is the space between O and S3 so I wouldn't waste much wire keeping them in series.

S1--O-S2
|
S3

 

[Grumpy365]

You need to run 3 conductor to the smokes. They are interconnected so any fire alarm will set off the whole house (That is code as of a couple of years ago) Code also says smokes have to be dual powered (battery and 110V)