I believe most Standards that have a requirement regarding it, require bleed off within 60 seconds.
From: Pete Perkins <00000061f3f32d0c-dmarc-requ...@listserv.ieee.org> Sent: Wednesday, September 30, 2020 10:48 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] [EXTERNAL] Re: [PSES] electric shock from capacitor discharge Rich et al, It’s been a while but, as I remember, servicing laser products used on industrial equipment required consideration of the stored cap charge that could be accessible to the technician. :>) br, Pete Peter E Perkins, PE Principal Product Safety & Regulatory Affairs Consultant PO Box 1067 Albany, ORe 97321-0413 503/452-1201 IEEE Life Fellow IEEE PSES 2020 Distinguished Lecturer p.perk...@ieee.org<mailto:p.perk...@ieee.org> Entropy ain’t what it used to be From: MIKE SHERMAN <msherma...@comcast.net<mailto:msherma...@comcast.net>> Sent: Wednesday, September 30, 2020 8:42 AM To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Subject: Re: [PSES] [EXTERNAL] Re: [PSES] electric shock from capacitor discharge I've seen some motor caps on industrial induction motors whose capacitance gave me pause. I think we specified a minimum bleed down time to allow before servicing. Mike Sherman Graco Inc. On 09/29/2020 10:21 PM Ted Eckert <000007cf6ebeab9d-dmarc-requ...@listserv.ieee.org<mailto:000007cf6ebeab9d-dmarc-requ...@listserv.ieee.org>> wrote: Hi Rich, I can’t think of many cases of modern IT equipment with a significant risk of capacitance discharge through the plug. However, I could foresee motor-driven equipment where it could be an issue. The manufacturer might put a power factor correction capacitor across the line to compensate for the inductive load of the motor. The motor should bleed off the charge of the capacitor, but there may still be some residual charge when the user pulls the plug. You probably wouldn’t have that large of a capacitor on a plug-connected motor appliance, but it is possible. It’s been more than a decade since I worked with large motor-drive appliances, so my memory of their workings isn’t great. I’m sure there is somebody on this list server who can correct any error I’ve made in my statements. Ted Eckert The opinions expressed are my own and do not necessarily reflect those of my employer. From: MIKE SHERMAN <msherma...@comcast.net<mailto:msherma...@comcast.net>> Sent: Tuesday, September 29, 2020 5:58 PM To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Subject: [EXTERNAL] Re: [PSES] electric shock from capacitor discharge Rich -- Are you including old CRTs as capacitors? I recall that, even with the early Macs, you had to be careful to discharge the tube if you were going to mess around inside. Mike On 09/29/2020 4:27 PM Richard Nute <ri...@ieee.org<mailto:ri...@ieee.org>> wrote: I am interested in knowing what constructions, situations, and products where a capacitive discharge into a body could take place. I am aware of the X and Y capacitors discharge at the prongs of a power plug. I don’t immediately know of other situations or products that might discharge a capacitor into a body. I would appreciate descriptions of such discharges into a body, not conjecture. Preferably, normal conditions and some single-fault conditions. Do we need to include capacitive discharge requirements in the safety standards? Stay safe! Rich - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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