THHN Riser Rated??

[mstrlucky74]

Running vertical #500 MCM for telecom grounding. They are asking for it to be “riser rated”. Is regular THHN riser rated? Or maybe a different insulation wire has to be run so it is “riser rated” Can’t find "riser rated" listed on any THHN cut sheets.

 

[sameguy]

UL1685 FT4/IEEE 1202
Is your wire rated as above?
Run bare.

 

[hbiss]

Some low voltage guy must have written that. Riser and Plenum rated relates to low voltage cables not to chapter 3 wiring methods. That's why you won't find anything about vertical flame spread in the NEC. But, as @sameguy said, run bare.

-Hal

 

[LarryFine]

But, as @sameguy said, run bare.

The wire, not you.

 

[mstrlucky74]

Some low voltage guy must have written that. Riser and Plenum rated relates to low voltage cables not to chapter 3 wiring methods. That's why you won't find anything about vertical flame spread in the NEC. But, as @sameguy said, run bare.

-Hal

Yes I agree and have seen/used riser for low voltage. So your saying 600v cable does not come riser rated. We are running it through sleeves when passing though the floors an bare in the closet. It's all vertical.

 

[infinity]

We just run THHN. Where can you find "riser rated" 500 kcmil? :roll:

 

[sameguy]

Type that first part in plus thhn you will find it, also xhhw.
So yes it is made, who ever is quoting on the wire for your bid you ask them.
https://www.encorewire.com/wp-content/uploads/EncoreWire-THHN-SSE.pdf

 

[hbiss]

No, that's just the spec for the insulation. Doesn't make it "riser rated". All THHN insulation is flame retardant. What do you think would happen if you had a panel full of wire with flammable jackets?

Lastly, THHN is not supposed to be run by itself. It needs to be in a raceway, cable, etc. at least when it is a current carrying conductor. So the manufacturers have no reason to spec it for installation unprotected.

In those instances where you are running grounds unprotected, the proper way is to use bare. A sharp AHJ or fire marshal should notice when insulated cable is used.

-Hal

 

[sameguy]

No, that's just the spec for the insulation. Doesn't make it "riser rated". All THHN insulation is flame retardant. What do you think would happen if you had a panel full of wire with flammable jackets?

Lastly, THHN is not supposed to be run by itself. It needs to be in a raceway, cable, etc. at least when it is a current carrying conductor. So the manufacturers have no reason to spec it for installation unprotected.

In those instances where you are running grounds unprotected, the proper way is to use bare. A sharp AHJ or fire marshal should notice when insulated cable is used.

-Hal

What is riser rating, meeting a spec.? I think it meets the spec.; most all wire is flammable in a panel, just how long will it burn.

THHN is routinely run as ground wire, on cable tray, I personally have run 500mcm green in the control tower of a major international airport.
The AHJ/ fire marshal didn't see it as a problem.

 

[hbiss]

What is riser rating, meeting a spec.? I think it meets the spec

Maybe it does but there is no such testing or listing for THHN. So if vertical flame spread is important it's not something to be used legally.

The test for riser use is obviously when the cable is supported vertically and ignited at the bottom, will the flame travel up the cable or how far will it go before it extinguishes itself. This is important because a riser is a cable installed vertically in a building through floors and you want to limit flame spread from a fire below.

Next question someone will ask is can you run THHN through an environmental air handling space? Is it plenum rated?

-Hal