Does EMT provide a 2 hour rating?

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Smart $

Esteemed Member
Location
Ohio
For the most part, wiring methods suitable for the type of construction are permitted in 2HR fire-rated walls. The wiring within the walls is not expected to outlast a 2 hour fire... but the wiring method is expected to not reduce the 2HR rating of the wall itself. Of greatest concern is penetrations that would permit fire advance quicker into the wall than if there were no penetrations. Fire blocking any wall penetration is what matters most.
 

iwire

Moderator
Staff member
Location
Massachusetts
The 20 second figure I gave came from a UL film I saw about testing MI cables. They pointed out that EMT with THHN inside was good for about 20 seconds when the EMT is subjected to the same test as MI.
 

cppoly

Senior Member
Location
New York
Thanks, I guess the reply with the 20 second rating answered my question. Just was curious about any type of cable in EMT. Same for RGS? Conduit does not give a rating to a cable right.
 

kwired

Electron manager
Location
NE Nebraska
Thanks, I guess the reply with the 20 second rating answered my question. Just was curious about any type of cable in EMT. Same for RGS? Conduit does not give a rating to a cable right.

Are you concerned with how long the cable will last or the structural fire rating associated with an EMT raceway?

The cable inside is likely not lasting very long unless the raceway is encased in concrete or other thermal barrier.

The raceway is allowed to penetrate a 2 hour wall - usually with proper sealing around the penetration, but the conductors inside will likely deteriorate if that 2 hour wall is pushed to it's thermal limits.
 

cppoly

Senior Member
Location
New York
A requirement for fire alarm cable riser cable in NYC is to be 2 hour rated. I was trying to see if by putting the fire alarm cable in EMT, would the entire fire alarm cable considered 2 hour rated now this it is enclosed in conduit?
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
A requirement for fire alarm cable riser cable in NYC is to be 2 hour rated. I was trying to see if by putting the fire alarm cable in EMT, would the entire fire alarm cable considered 2 hour rated now this it is enclosed in conduit?

Clearly 100% NO!
But if you, for some reason, put compliant cable like MI inside EMT it will remain compliant.
 

mike1061

Senior Member
Location
Chicago
A requirement for fire alarm cable riser cable in NYC is to be 2 hour rated. I was trying to see if by putting the fire alarm cable in EMT, would the entire fire alarm cable considered 2 hour rated now this it is enclosed in conduit?

Why didn't you say that in the first place. The original question was very unclear.
Thanks
Mike
 

ron

Senior Member
A requirement for fire alarm cable riser cable in NYC is to be 2 hour rated. I was trying to see if by putting the fire alarm cable in EMT, would the entire fire alarm cable considered 2 hour rated now this it is enclosed in conduit?

We live that requirement and it is weird how it generally gets ignored. We specify the MI product, but often gets accepted as regular NYC rated fire alarm cable in EMT.
 

MasterTheNEC

Host of ElectricianLIVE.com
Location
McKinney, Texas
Occupation
Master Electrician & Director of Codes and Standards
If you run cables in EMT conduit, does this provide a 2 hour fire rating?
In of itself...NOPE.....Now elaborate in more detail. What type of cables are you placing in the EMT....and that may not even matter.
 
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