Jim - Consider that equipment in an existing installation might have been evaluated to UL1459 and CSA22..2 No.225. No fixed creepage or clearance requirements were incorporated into those standards for other than at field wiring terminals. Electrical spacings were (are, until 2005) evaluated by DVWT. A completely different animal.
Regards, Peter L. Tarver Nortel [email protected] > ---------- > From: JIM WIESE[SMTP:[email protected]] > Sent: Wednesday, April 29, 1998 1:16 PM > > I appreciate your comments, and I did not imply telco's do not provide > protection. In fact they do a great job. However the spacings on an > AT&T D4 channel bank (for instance, I could list endless others) are > less than .3mm from the tip/ring of one channel to the tip/ring of > another channel (look at the spacings of the "amp champ" pins). Since > adjacent channels can have cards that are TNV1, TNV2, TNV3, or Hazardous > voltage secondary circuits (190VDC fractional T1), separation is <.3mm. > According to UL 1950 3rd edition, the creepage at 190VDC is 2.0mm (1.5mm > at 120VDC). .3mm is substantially deficient with regard to UL 1950 3rd > edition. In other words the network has <.3mm between different TNV's > at the C.O., yet UL 1950 3rd Edition would require 2.0mm at the > terminal device. What is the point if the network is deficient in > spacing. Also network equipment that happens to be evaluated for a > listing is almost surely done to UL 1459 or a UL category such as > "DUZO". The only thing required is a dielectric test, not spacings. By > the way, .3mm will pass a 1000VAC dielectric in most cases. > > Jim > > Jim Wiese >
