mstrlucky74
Senior Member
- Location
- NJ
why is there 120V running to these devices?
Sounds good to me. Nothing says the "in" and "out" conductors/cables can't be in the same raceway.Scenario. Fire alarm is in full conduit and adjacent speaker and strobes have to be on separate ckts.
Question, wouldn’t putting a 4” box above the device alleviate you having to run 2 conduits from the device(in and out)?
What’s the more practical way?
Scenario. Fire alarm is in full conduit and adjacent speaker and strobes have to be on separate ckts.
Question, wouldn’t putting a 4” box above the device alleviate you having to run 2 conduits from the device(in and out)?
What’s the more practical way?
Your saying separate ckts, not separate conduits.... One pipe, two circuits...
Gary
Certain systems (I believe Class A) only allow up to 10' of the supply and return loop wiring to be a common raceway.
why is there 120V running to these devices?
Certain systems (I believe Class A) only allow up to 10' of the supply and return loop wiring to be a common raceway.
Revisiting this. If you have say a pull station the in to the device and out from the device to the next is not supply and return, it's on the supply cables? The return on class A is just the return path from the last device.....it's doesn't connect to any devices.
If it's a loop of many devices the return from one device will supply the next device in the loop. The last device will have a return cable that goes back to the FAP with no other devices connected.
Don't you guys use MICC for fire alarm systems?
It is usually orange/red here to distinguish as cable for that specific duty. We rarely use EMT these days.Only if someone is brandishing a large caliber weapon, say, a 155mm howitzer. MI, as it's known on this side of the pond, is used for bringing power to the panels, if at all.
It is usually orange/red here to distinguish as cable for that specific duty. We rarely use EMT these days.
I did a quick lookup for MICC before my previous reply, and it seems to be mineral insulated conductors, which is basically a copper rod inside a copper pipe. The only way you use it here is if the spec or AJH forces you to. It's heavy, hard to hump around, and the joining methods are tedious, all leading to a very expensive install. I see it's available with a PVC coating which could be used for color-coding
It's because the heat resistant/non-flammable property that it it gets used for fire alarm systems here.
For signal line circuits and notification appliance circuits it's more common to use circuit integrity (CI) or circuit integrity in conduit (CIC) cable. CI is in a state of flux now because UL pulled all the certifications for the current products due to some field testing (some have apparently been re-certified), but it is cable with an intumescent cover that is designed to survive a 1,200°F fire for 2 hours and then take the full force of a 1-1/2 hose stream and continue to conduct a signal. CIC is a similar product but can ONLY be installed in conduit.