Do you use RHH/RHW (not listed as XHH/XHHW) for branch circuits wiring in the building?

[zemingduan]

As I understand XHH or XHHW is acutally a specific type of RHH that use XLPE insulation. As I understand RHH/RHW(not listed as XHH or XHHW) are allowed by NEC to be used for general lighting, receptacle branch circuits wiring in the building. The different between RHW and RHH is water resistant. But I see most specifications by engineer specify THHN, THWN, XHHW instead of RHH or RHW. And RHW is commonly rated together with USE/USE-2 used for underground service entrance. What's the reason?

The difference between RHH and THHN, RHW and THWN is the insulation and jacket. RHH and RHW use rubber but THHN and THWN use thermoplastic PVC and nylon jacket.

Does any manufacture make cable that is only rated with RHH or RHW? I am an electrical engineer and the conductor rating always confuses me...

 

[electrofelon]

As I understand XHH or XHHW is acutally a specific type of RHH that use XLPE insulation. As I understand RHH/RHW(not listed as XHH or XHHW) are allowed by NEC to be used for general lighting, receptacle branch circuits wiring in the building. The different between RHW and RHH is water resistant. But I see most specifications by engineer specify THHN, THWN, XHHW instead of RHH or RHW. And RHW is commonly rated together with USE/USE-2 used for underground service entrance. What's the reason?

The difference between RHH and THHN, RHW and THWN is the insulation and jacket. RHH and RHW use rubber but THHN and THWN use thermoplastic PVC and nylon jacket.

Does any manufacture make cable that is only rated with RHH or RHW? I am an electrical engineer and the conductor rating always confuses me...

Understanding Differences Between RHH/RHW-2 & XHHW/XHHW2 Building Wire

RHW and XHHW/XHHW2 are the two commonly confused cable ratings that indicate a specific type of building wire. In fact, these two are more similar than different. One of those is the general cable rating, whereas the other is the particular cable type. To fully understand the differences between...

nassaunationalcable.com

 

[curt swartz]

Old type "R" wire had rubber insulation. XHHW has XLP insulation. Modern type RHH/RHW uses the same XLP insulation used for XHHW. The insulation on XHHW is much thinner than the insulation on RHH/RHW.

 

[electrofelon]

Old type "R" wire had rubber insulation. XHHW has XLP insulation. Modern type RHH/RHW uses the same XLP insulation used for XHHW. The insulation on XHHW is much thinner than the insulation on RHH/RHW.

According to the southwire spec sheets, xhhw is 55 mils in 2/0 thru 250 sizes. For their RHW/USE it's 80 mils for #1 thru 4/0 and 95 mils for 250

 

[zemingduan]

Understanding Differences Between RHH/RHW-2 & XHHW/XHHW2 Building Wire

RHW and XHHW/XHHW2 are the two commonly confused cable ratings that indicate a specific type of building wire. In fact, these two are more similar than different. One of those is the general cable rating, whereas the other is the particular cable type. To fully understand the differences between...

nassaunationalcable.com

Thank you. I also read this article. My understanding came from this article. LOL. I am just curious, why I don't typically see people specify RHH/RHW but THHN, THWN, XHHW for branch circuit wring.

 

[don_resqcapt19]

Thank you. I also read this article. My understanding came from this article. LOL. I am just curious, why I don't typically see people specify RHH/RHW but THHN, THWN, XHHW for branch circuit wring.

Mostly conduit fill and wire pulling labor. The only time I ever specify XHHW is for underground or for the conductors between the output of a VFD and the motor. For anything else, it will be THWN-2.