Not 100% sure, but I would imagine the CO Sensors would be on a different Loop than the Smoke Detectors.
Maybe the Drawing is showing the 4 Wires as:
* 1 Pair = Power,
* 1 Pair = Zone Loop.
Best to do here is an RFI (actually, an RFC) to whomever drew the plans you are referencing.
Maybe attempt to get an "Expedited RFI", by mailing / faxing / E-mailing / calling the designer directly, in conjunction with sending the RFI through the standard Red-Tape Channels.
Nevertheless, I would suggest requesting clarification from the designer, and verify the design intent conforms with all Local Codes that the AHJ will be referencing (Building, Electrical, Mechanical and Fire Department).
Looks like I may have opened the proverbial "Can 'O Worms"!!!
Scott " 35 " Thompson Just Say NO To Green Eggs And Ham!
#101361 - 03/08/0705:39 PMRe: CO detectors and Smokes
If you are talking residential, both Kidde and Firex make smokes and combo CO/Smoke's that interconnect. We have to put a smoke in every bed and one outside the sleeping areas, and typically put a combo CO/smoke in the hallway if the house has gas appliances.
#101363 - 03/09/0710:11 AMRe: CO detectors and Smokes
Smokes and CO detectors are required to have a distinctly different alarm sound. I have no idea if the residential combo devices alarm through other devices (read smokes), but I would think that they don't. I have not yet tied the two together, but I may be wrong.
Interesting, I have worked with ADA/ADABAG ( a US standard for accessibility containing the Law for government and non-government installations) and though I provide notification for the deaf for smoke, I have not for CO. I will have to research this.
#101364 - 03/09/0711:18 AMRe: CO detectors and Smokes
The distinct sound requirement is in the IBC 909.9.2. I have yet to find references requiring CO alarms, I am sure I am just looking in the wrong locations (we do have one jurisdiction in Utah that has a law requiring them in all residences).
I will have to get back to this in a week, those who know the IBC and ADA are all gone today and I am out all next week. I am interested to know myself.
#101365 - 03/09/0712:00 PMRe: CO detectors and Smokes
909 of the IBC is on Smoke Control. We have been using CO detectors here in CT for a while now, and there is no reason to have distinctive different alarms. We allow and even encourage these two similiar device to be interconnected. ( compatibility?, use the same manufacturer) The object is to get the folks up and out of the building. Someone can then call the fire department, and they can investigate why the alarms went off: Was it a fire or was it CO gas accumulation? (They have gas detectors on their trucks).
#101367 - 03/09/0705:21 PMRe: CO detectors and Smokes
The local adopting agency (usually the state, but sometimes the county or municipality) adopts the model code, then will add to and/or modify certain sections of the model document. Some states will also have the model code printing press print a specific state modified version of the building code. (Florida, California, Massachusetts and Connecticut come to mind)
The model building codes do not require CO detectors at this time (2003 IBC or IRC) I haven't checked the 2006. The NEC never has required fire detectors/alarms or CO detectors/alarms. This always has been a function of the building code.
Get on line, check out your state for the codes adopted, and their modifications of the model code.