xhhw

T

timmermeier

Member
Location
alton il
Occupation
electrician
Can i use xhhw in conduit?????????????????????????????????????????????????????????????????????????????????????????????????????????????????
 
roger

roger

Moderator
Staff member
Location
Fl
Occupation
Retired Electrician
Yes, it's mandatory for Isolation Power Systems
 
roger

roger

Moderator
Staff member
Location
Fl
Occupation
Retired Electrician
Oh, I forgot !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
infinity

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
LarryFine said:
Opening posts require at least 100 characters to weed out automated spamming.
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Is that the reason, very interesting. We've asked to have it lowered to a smaller number of characters but we've been told that it's the software minimum. For the record you never really see any spam here because all posts by a new poster are screened by a moderator. 🤫
 
Jraef

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
To be clear, the 100 character minimum only applies to your very FIRST post as a new member.

Most of the time, the Mods on the eastern time zones do most of the spam cleaning because they see them first. I'm on the west coast, but some nights when I can't sleep, I take a look for spam posts and have some vicarious fun killing them. Makes me feel useful...
 
roger

roger

Moderator
Staff member
Location
Fl
Occupation
Retired Electrician
ramsy said:
I see the exception to roof top derating unique to XHH?, but notzing else.
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Well it's hard to find the exception to notzing else. ;)

It's not an NEC rule, it is the need for the conductors to have a die-electric strength of least 3.5

Here's an excerpt of SQ D's iso power recommendations.


Use cable with the best insulation possible. The insulation on the cable should have a dielectric constant of 3.5 or less and, in this regard, all XHHW wire is not created equal. Square D recommends Rome Cable brand, catalog number VW-1 XHHW-2 Spec 2110 because it seems to consistently give the best results. The particular wire you are using may be listed as having a dielectric constant of less than 3.5, but wire manufacturers generally do not list an absolute dielectric constant. So you don?t know if the wire?s dielectric constant is 3.49 or 2.49. Wire insulation types THHN, THHW, THW, THWN and TW are not suitable for use on isolated power systems.

Do not use wire pulling lubricant of any kind on the branch circuits. Wire pulling lubricants tend to change the dielectric of the insulation. If in doubt about the ability to pull-in the conductors, use a larger conduit. The insulation on XHHW wire is thicker than THHN and not as slippery. So plan ahead and ask you distributor for some wire samples.
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