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Question 1: We have a hospital where there are a number of patient rooms that each have a separate bathroom accessable only from within the patient room. The patient room has a smoke detector and the bathroom a heat detector. The combined total of these rooms is much less than 100sq m. Clause 18.104.22.168 C of CAN/ULC-S524-06 allows a single conduit/raceway drop to pick up multiple field devices installed within a single room not exceeding 100sq m. Would this Clause allow a single conduit drop into the patient room to pick up the smoke detector and then a single conduit between bedroom smoke detector and bathroom heat detector if the combined total is less than 100sq m or do we have to treat bathroom and bedroom as separate rooms where a separate conduit drop would pick up the bedroom smoke detector and yet another separate drop would pick up the bathroom heat detector (as the Clause seems to imply)? Can we consider the sum total of bathroom and bedroom as a "single room" for the purposes of this rule if the sum total is less than 100sq m?
Question 2: In the same hospital, we have two rooms in a National Building Code of Canada required fire alarm zone that have a combined total area of much less than 100 sq m. As in Question 1, (with reference to our style A DCL) do we have to treat the two rooms as two separate single conduit drops to pick up a detector in each room or can we have a single conduit drop into this zone to pick up all detectors in both rooms?
Question 3: In the same hospital, we have a containment room with a single smoke detector. This room is less than 100 sq m. The style A DCL loop will pass by this room in another National Building Code of Canada required fire alarm zone. Clause 22.214.171.124 B or C of CAN/ULC-S524-06 allows a single conduit/raceway drop to pick up this smoke detector. Clause 5.14.2 requires isolation modules utilized when entering and leaving this containment room.
(a)Since we have both the primary wiring circuit and the alternate wiring circuit within a single conduit into this containment room from another zone, wouldn't Clause 5.14.2 require two isolation modules for the primary wiring circuit (one each on either side of the fire wall) and two isolation modules for the alternate wiring circuit (one each on either side of the fire wall) for a total of 4 isolation modules? Am I correct here?
(b)Clause 5.14.6 requires a minimum of 400mm of horizontal offset on either side of the firewall between the containment room and the other zone where the circuits are being fed from. What is a logical application of this rule? Would one leave a room with an isolation module, drill into the containment room and then immediately make a 90 degree bend and run the 400mm horizontal offset before installing the second isolation module? If 4 isolation modules are required in this situation, what physical spacial arrangement would satisfy Clause 5.14.6?
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1. You don't have to extend the Class "A" loop into the patient room. You can mount an isolator outside of the patient room and "T" tap into the room and pick up both devices on a "B" branch circuit. If you do elect to put the "A" loop into the room as you describe, I would suggest installing two isolators on the outside of the patient's room (to preserve the integrity of the loop). I'm not concerned so much with "open" circuits caused by removal of devices or a single failure. I'm more concerned with "short" circuits within the room. If a short occurs in any of the rooms tied to the circuit, it's going to take out that entire part of the loop unless you use isolators. Treat each patient's room as you would a suite in a residential occupancy including suite isolators on the audible (and visual) signal appliances in the room.
2. With single detectors in smaller rooms, you have to treat them as separate rooms unless they're co-joined in which case I would treat them as a suite. Again, you could use a Class "B" branch circuit protected by an isolator.
3. Isolator on the outside of the room. Isolator base for the detector. "T" tap into the room in a "B" branch circuit from the Isolator on the outside.
There is one governing principle you should keep in mind. Survivability of the system is paramount. You must try to mitigate what will happen in a wire to wire short condition (which is the worst case type of scenario). You want to try and minimize the number of detectors that will be compromised by such a condition.
Hope this helps!
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