Personally . . . my take on this specific issue is to find the cause NOT treat the symptom . . . there is (obviously) something wrong there. I wouldn't put my family (or myself) at risk doing something like adding NTCs in my house wiring when that's not a normal thing to do . . . That's my personal opinion . . . John Juhasz Fiber Options Bohemia, NY
-----Original Message----- From: Peter Tarver [mailto:ptar...@nortelnetworks.com] Sent: Thursday, July 20, 2000 11:01 AM To: Jim Eichner; emc-p...@majordomo.ieee.org Subject: RE: Are NTCs Safe to Use in Electrical Equipment I really don't have a clear idea of whether or not your solution will work. Let us know. NTCs, as with most thermistors, get very hot when in their switched state. For the NTC, that's it's steady-state condition. I wouldn't put this in a junction box with other wiring, unless you're absolutely certain all the wiring can take the temperatures they'll encounter (for normal household wiring, likely not). Rather, for the sake of your experiment, put the NTC in a separate (probably should be metal) box that's in-line with the receptacle, with appropriate goesintas and goesouttas. Be certain to use your best safety engineer's hat for this activity. Regards, Peter L. Tarver, PE Homologation Engineering Nortel Networks ptar...@nortelnetworks.com -----Original Message----- From: Jim Eichner [ mailto:jim.eich...@xantrex.com <mailto:jim.eich...@xantrex.com> ] Sent: Monday, July 10, 2000 11:35 AM To: emc-p...@majordomo.ieee.org Subject: RE: Are NTCs Safe to Use in Electrical Equipment On the subject of NTC's, please allow me a slight detour from the compliance world to the real world. I have a circuit in my house that blows light bulbs far more often than any other. I can't determine any reason for this - the voltage seems normal and there aren't any transient-producers on that same circuit (that I'm aware of). Long life and rural-duty bulbs make little or no difference. Instead of figuring out the root cause, I'm considering resorting to trying to deal with the symptom (blown bulbs) by putting an NTC in series with the light fixture somewhere. My thinking is that the mechanism that blows an incandescent bulb filament is related to the high inrush current into the cold (and therefore low R) filament, and the physical and thermal stresses that that inrush causes. Any comments on how likely this is to help, and whether or not I can safely put an NTC in an junction box full of wires? I'd check the NTC's temperature under load (they get hot) and compare that the the temp. rating of the wires in the box. I'd also insulate the bare legs of the NTC and try to make sure it isn't touching anything else. Anyone familiar with the failure modes of these things? Thanks, Jim -----Original Message----- From: Peter Merguerian [ mailto:pmerguer...@itl.co.il <mailto:pmerguer...@itl.co.il> ] Sent: Monday, July 10, 2000 7:58 AM To: emc-p...@majordomo.ieee.org Subject: Are NTCs Safe to Use in Electrical Equipment Dear All, I have seen some design where NTCs are used to limit inrush currents in motion controllers. Q. Are NTCs safe and reliable as means to limit inrush currents? Q. Are there safety considerations to consider for circuits employing NTCs? Q. Are there any Approved (previously evaluated) NTC components out there? I appreciate all of your comments and/or links regarding the use of NTCs in electrical equipment. Thanks Peter Merguerian Managing Director Product Testing Division I.T.L. (Product Testing) Ltd. Hacharoshet 26, POB 211 Or Yehuda 60251, Israel Tel: 972-3-5339022 Fax: 972-3-5339019 e-mail: pmerguer...@itl.co.il website: http://www.itl.co.il <http://www.itl.co.il> ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson: pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson: pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
