As for formal direction for use of a CTL Decision, Mr Nute' subsequent post provides his usual lucid reply.
Unless there is a national difference, NRTLs have always used CTL decisions. For the North America-specific stuff, there are UL PAGs, CSA Notifications, and ANCE directions. But this is minor stuff, there is the big geographical issue for interpretation of requirements. The harmonization of North American product safety standards will probably increase as it has been codified by the joint publication of "Procedures for Harmonizing ANCE/CSA/UL Standards". This document specifies the use of an IEC standard, where applicable and available, as 'the' reference. It is my sense that we will see the CEC, NFPA (NEC), and NOM-001-SEDE continue to converge and provide end-use installation guidance for construction materials that are defined in product safety standards for connection to mains power. Conversely, I am not certain if it was ever the intent for IEC60364 to provide any guidance to what happens after the mains connection. Note that the NEC has been adopted by most Central and South American states. Brian > -----Original Message----- > From: [email protected] > [mailto:[email protected]] > Sent: Wednesday, May 11, 2011 5:48 PM > To: [email protected]; [email protected] > Subject: RE: [PSES] UL/60950-1 Cl. 2.1.1.7 Probe > > > CTL is for IEC only, right? John's question was regarding > UL60950. Do the NRTLs use the CTLs for the UL/ANSI > Standards? And I would imagine the equipment used shall > comply with all necessary calibrations. > > -----Original Message----- > From: Brian O'Connell [mailto:[email protected]] > Sent: Wednesday, May 11, 2011 7:07 PM > To: [email protected] > Subject: Re: [PSES] UL/60950-1 Cl. 2.1.1.7 Probe > > I am probably missing an obvious point. If the CTL has > addressed 2.1.1.7 and said that the requirement simply is > >100 Mohm || <25 pF, why are we going through this special > probe construction/evaluation stuff and not just buy an OTS > probe that meets this (I see a Tek and HP probe that will work)? > > Another question - will the probe be subject to ISO17025 calibration? > > Brian > > > -----Original Message----- > > From: [email protected] [mailto:[email protected]]On Behalf Of > > [email protected] > > Sent: Wednesday, May 11, 2011 4:41 PM > > To: 'John Woodgate'; [email protected] > > Subject: RE: UL/60950-1 Cl. 2.1.1.7 Probe > > > > Hi John: > > > > > When conducting the voltage decay measurement, the measurement > > > is either made with, or referred to, an instrument > having an input > > > impedance consisting of a resistance of 100 Mohms ± 5 Mohms > > > in parallel > > > with an input capacitance of 25 pF or less. > > > > Agreed. > > > > > So any 100: 1 probe can probably be used. I would expect the > > > capacitance > > > of a 100:1 probe to be much less than 15 pF, so just add > > extra shunt > > > capacitance to taste. > > > > Be aware that not all 100:1 probes have a 100 Mohm > > input resistance. The 100 Mohm input resistance is > > critical to the correct measurement. > > > > The capacitance is of no consequence since the measurement > > only applies if the capacitance is 0.1 uF or more. Probe > > capacitances are in the range of 2 to 20 pF and are > > negligible when in parallel with 0.1 uF. See my "Technically > > Speaking" column in Volume 4, Number 4, December 2008, > > issue of IEEE PSES "The Product Safety Engineering > > Newsletter." > > > > This is available to IEEE PSES members at: > > > > http://ewh.ieee.org/soc/pses/society/08V4N4.pdf > > > > > > Best regards, > > Rich - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
