High-Temp Building Wire?

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Jon456

Jon456

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I was reading a manual for a commercial kitchen ventilation hood and came across this warning:

All field wiring on top of the hood must use high temp wire and wire nuts (black). Wiring must be routed through hard or flex conduit. Route and attach all conduit on top of, or above, structural joists (Hat Channel) on top of hood. Conduit cannot contact the surface of the hood ceiling.
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Unfortunately, there is no definition or specification of "high temp wire" given. So out of curiosity, I did a search for high temp building wire. I was particularly curious if there was a "high-temp" version of MC. But the only high temp wire I could find all seemed to be specialized industrial wire. Like this: https://www.awcwire.com/producttoc.aspx?id=high-temperature

Is that what is supposed to be used for commercial kitchen hoods? If so, what kind of "flex conduit" would be appropriate for this application?
 
I have wired many kitchen fire-suppression systems, and have always used standard THHN/THWN in the wiring methods stated above. I have seen sleeved factory wiring in new hoods, but regular wiring should be okay as long as you keep it off the top of the hood like mentioned.
 
Thanks, Larry. It certainly seemed odd to me that they'd issue such an important warning without giving an actual temperature rating or wire type specification. But at least they stipulated the color of the wire nuts!
 
Jon456 said:
Unfortunately, there is no definition or specification of "high temp wire" given.
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I agree. They also don't say what "on top of the hood" means either as far as distance away from the sheet metal. I suppose the sheet metal can get pretty hot, but like a stove, there should be required clearances given from combustibles if the heat is that great.

-Hal
 
The correct wire for the 150deg application is type Z which is a NEC designated type (there is alot of different high temp wire, hookup, aerospace, etc out there but most of them aren't listed in chapter 3) southwire makes it. There's also type FEP for 200deg which may be easier to get.
 
hbiss said:
They also don't say what "on top of the hood" means either as far as distance away from the sheet metal. I suppose the sheet metal can get pretty hot, but like a stove, there should be required clearances given from combustibles if the heat is that great.
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To me, this language is unambiguous because they state, "Route and attach all conduit on top of, or above, structural joists (Hat Channel) on top of hood." The "or above" implies that "on top of" means "in contact with." What they are saying is that the conduit can be touching the top surface of the hat channel or it can be above the hat channel. That also means it cannot be below the top surface of the hat channel, and specifically cannot be touching the top sheet metal surface that comprises the hood ceiling.
 
Todd0x1 said:
The correct wire for the 150deg application is type Z which is a NEC designated type (there is alot of different high temp wire, hookup, aerospace, etc out there but most of them aren't listed in chapter 3) southwire makes it. There's also type FEP for 200deg which may be easier to get.
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Thanks for this info. I had previously searched Southwire's building wire for "high temp" wire but came up empty-handed. I didn't know they had a separate industrial division.

Looking at Southwire's FEB-insulated wire options, they have UL1332, UL1901, UL1330, UL10203, and "UL Type FEP". Besides different insulation thicknesses for the first three, I'm not sure what the other differences are, and which standard to choose for this type of application.

Regarding the flexible conduit, I found this:

http://www.afcweb.com/liquid-tuff-c...mperature-liquidtight-flexible-metal-conduit/

It's rated for temperatures up to 150°C so it should be ideal. But it's non-UL rated and "designed to be used for specific applications where Underwriters Laboratories Inc. (UL) or other agency approvals are not required." So I don't know if it can be used in this type of application.
 
synchro said:
The black wirenuts mentioned may be referring to one's like these rated at 150 deg C. :
​​​​​​
https://idealind.com/content/dam/el...stOn/WireNut/HighTempWireNut_Instructions.pdf
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What I just noticed about these Ideal high-temp wire nuts is that the largest model (59B) can only be used with one #12 wire. It seems bizarre they don't make one large enough to connect at least two #12 wires.

Gardner Bender makes a High-Temp Wire Nut (GB-4) that can accept a max of two #12.
 
Jon456 said:
Thanks for this info. I had previously searched Southwire's building wire for "high temp" wire but came up empty-handed. I didn't know they had a separate industrial division.

Looking at Southwire's FEB-insulated wire options, they have UL1332, UL1901, UL1330, UL10203, and "UL Type FEP". Besides different insulation thicknesses for the first three, I'm not sure what the other differences are, and which standard to choose for this type of application.

Regarding the flexible conduit, I found this:

http://www.afcweb.com/liquid-tuff-c...mperature-liquidtight-flexible-metal-conduit/

It's rated for temperatures up to 150°C so it should be ideal. But it's non-UL rated and "designed to be used for specific applications where Underwriters Laboratories Inc. (UL) or other agency approvals are not required." So I don't know if it can be used in this type of application.
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I believe it would be this one http://industrial.southwire.com/en/cablespec/download_spec/?spec=42024

FEP can get confusing because it is the name of the insulation material AND the name of the NEC type, so you can have FEP wire that is not NEC type FEP. Anything with a UL infront of it, means it is a UL wire type and not a NEC wire type which means it cant get used as building wire (there are some with dual or multiple type listings that do allow use as building wire)
 
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