XHHW vs THWN

Status
Not open for further replies.
V

vw55

Member
Location
California
Is there a distinct advantage to using XHHW insulated conductors in underground feeder runs instead of THWN insulated conductors? I've heard differing opinions regarding size, durability, cost, etc. I know the XHHW is not high heat rated if installed in wet locations unless its XHHW-2 stamped. Any comments would be much appreciated.
 
Re: XHHW vs THWN

XHHW will have a lower leakage insulation rating- for lack of a better word- that could be of some benefit in a long underground run, but I would not consider it distinctive.
 
Re: XHHW vs THWN

XHHW-XLP2 is direct burial rated and will hold up much better in an underground raceway. Also the insulation is thicker and less likely to fail.
I have had many runs of THHW in an underground conduit fail. Our specs only allow XHHW in underground conduit runs, but this is for critial applicataions such as roadway lighting and wastewater...
 
Re: XHHW vs THWN

Tom...what kind of problems have you been having with thhw in underground conduit. I've been using a lot of that lately.
 
Re: XHHW vs THWN

Not trying to answer for Tom, but I agree with him and prefer XHHW for underground longevity not to mention the stronger dielectric strength Rick points to.

Roger
 
Re: XHHW vs THWN

How do you guys compare the difficulty of installation between THWN and XHHW?

I think that XHHW is more difficult to pull in and more easily damaged.

How do you guys find the cost and availability between the two compare?
 
Status
Not open for further replies.
Top