Fire Alarm Conduit

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mstrlucky74

Senior Member
Location
NJ
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?
 

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kwired

Electron manager
Location
NE Nebraska
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?
Sounds good to me. Nothing says the "in" and "out" conductors/cables can't be in the same raceway.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Certain systems (I believe Class A) only allow up to 10' of the supply and return loop wiring to be a common raceway.
 

Gary11734

Senior Member
Location
Florida
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
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Your saying separate ckts, not separate conduits.... One pipe, two circuits...

Gary

That's what I was thinking, unless the project spec calls for a separate pipe for one of them. The Port Authority of NY/NJ is famous for this.
 

mstrlucky74

Senior Member
Location
NJ
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.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
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.
 

Alwayslearningelec

Senior Member
Location
NJ
Occupation
Estimator
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.

I don't follow "return from one device will supply the next".
 

sameguy

Senior Member
Location
New York
Occupation
Master Elec./JW retired
Daisy chained, the circuit leaves the FA controller to the first, second, third,..., device and ends (class A) back at the controller where the end of line resistor sits.
The in/out is, in from the previous device, out to the next device, we mark the (in) cable for aiding in trouble shooting.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Don't you guys use MICC for fire alarm systems?

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.
 

Besoeker3

Senior Member
Location
UK
Occupation
Retired Electrical Engineer
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.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
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
 

Besoeker3

Senior Member
Location
UK
Occupation
Retired Electrical Engineer
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.
 
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gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
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.
 

Besoeker3

Senior Member
Location
UK
Occupation
Retired Electrical Engineer
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.

Thank you Mr Gadfly.
I find it interesting and educational to have discussions here and appreciate your input.
I've been around a bit in different parts of the world and have seen different things. Mostly industrial. Odd voltages. Kit exported from one part of the world to another. The need to arrange compliance. But a lot of it was custom designed and built. I was just the designer. One of my first was a paper machine in Taiwan. Year 1973. A mill closed down in Grimsby, UK. A company in Taiwan bought the assets. I, and a mechanical engineer, went to supervise the installation. Ancient DC system with electromechanical differential face plate regulators. An eight moth project

Not your common or garden stuff. But educational in may ways.
 
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