Conductors: Using RHW-2

Status
Not open for further replies.
lordofpi

lordofpi

Senior Member
Location
New Jersey
Okay, a quick question of clarity. I am well aware of the differences between TH*N conductors and XHH* in terms of insulation, applications, basic chemical makeup, etc. In what cases do RH* conductors become more useful than the aforementioned? I have never had to use them, and I am sure they are around for a reason. What is different about them?

While we're at it, why are THW and TW conductors still made? Any special applications?
 
But is that any better protector than XHHW-2? Both are thermoset, from my understanding. I don't even understand what the physical difference is between them.
 
We recently pulled in some RHW-2 which had a 2 hour fire rating (printed right on the cable, whatever that means). I don't see the same nomenclature printed on XHHW.
 
Well, I just did a quick search on XHHW-2 to see what its fire rating was, and came up with Abbott Wire's description:

"Can be used for general purpose wiring, for power distribution and branch circuit wiring, where a cable having superior flame retardence is required."

I couldn't quickly find anything about actual time, but it must be around. Anyone notice that Google's search isn't _quite_ up to as relevent as it used to be?
 
lordofpi said:
C'mon, Greg, you always seem to be able to get me out of these conundrums. ;) :cool:
Click to expand...

Sorry, I am still searching in UL Fire rated cable.


Trevor was that pull to the Pump controller? I did see in 08 they revised the pump feeders to 2 hr.
 
dcspector said:
Sorry, I am still searching in UL Fire rated cable.


Trevor was that pull to the Pump controller? I did see in 08 they revised the pump feeders to 2 hr.
Click to expand...


It was an generator feeder for a transfer switch providing power to a fire alarm fuse cutout panel.
 
No, it's called Really Horrible Wire. This stuff is almost impossible to pull in when compared to THHN.
 
Well, from what I could find, it seems that RHW is generally insulated with an ethylene propylene rubber compound (hence the R), which I guess is what makes it hard to pull. UL seems to now allow a standard XLPE coating on RH*, though (don't know why). On top of the higher fire rating, as others have already noted, RH* wire can be rated to 2000 V, which is not something available on conductors such as XHHW-2. It would appear that this conductor is listed for direct burial. Is this true, or must it be in a cable assembly (i.e., USE-2) or raceway?
 
Last edited:
Lifeline's RHH cable is 2 hour rated. I assume it is the same as RHW except not wet location rated. The insulation is ceramified silicone rubber. The ceramic hardens when it gets hot which protects the cable giving it a 2 hour rating in emt.
 
Status
Not open for further replies.
Top