Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ames!sun-barr!newstop!texsun!pollux!attctc!vector!telecom-gateway From: kitty!larry@uunet.uu.net (Larry Lippman) Newsgroups: comp.dcom.telecom Subject: Fire Hazards of Dial Light Transformers Message-ID: Date: 4 Sep 89 00:40:03 GMT Sender: news@vector.Dallas.TX.US Lines: 34 Approved: telecom-request@vector.dallas.tx.us X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@vector.dallas.tx.us X-TELECOM-Digest: volume 9, issue 346, message 1 of 7 In article macy@fmsystm.UUCP (Macy Hallock) writes: > Rumor had it that more than one residence burned > to the ground due to shorted dial light transformers ! This is more than a rumor - it's true! Several years ago there was a "recall" notice about dial light transformers which appeared in major newspapers. The notice advised subscribers how to identify the transformer, and even had a full-size outline diagram to compare against the transformer. As far as I can recall, the offending transformer was NOT the familiar 2012A, but was a KS-spec equivalent which had a somewhat larger "footprint" - closer to the 85-type transformer in size. The 2012A and 2012B (18-volt version for speakerphones, repertory dialers and other accessories) were rather carefully engineered to undergo magnetic saturation upon short circuit, thereby limiting current to a safe level (not much more than 1 amp RMS), while limiting copper heat loss in the transformer to "safe" temperature levels. In addition, there is enough current-carrying capacity in station wiring (including the tinsel conductors of a station or handset cord) so that at least 1 ampere of current can be carried without any significant heating effect. So, the point is, I don't believe that the 2012A was the "offender'. Newer transformers become "cheaper", and therein lies the problem. As an example, the 2012D (an 18 volt transformer) is a real piece of crap; not only does it not have the protective potting of its 2012B predecessor, but even the AC power plug prongs are loose. <> Larry Lippman @ Recognition Research Corp. - Uniquex Corp. - Viatran Corp. <> UUCP {allegra|boulder|decvax|rutgers|watmath}!sunybcs!kitty!larry <> TEL 716/688-1231 | 716/773-1700 {hplabs|utzoo|uunet}!/ \uniquex!larry <> FAX 716/741-9635 | 716/773-2488 "Have you hugged your cat today?"