Ralph, This might be true but that is not how we saw it way back when. The 240VA "Energy Hazard" was not a consideration for the protection against Fire but a limit value for accessible parts by the User. We still today consider accessible circuits, regardless of the voltage, to be "Hazardous Live" if the circuit exceeds 240VA. This requirement is not specifically called out in our working safety standard (IEC/EN 61010-1 for Laboratory Equipment) but we still take this condition under consideration especially with products that exposes the user to high currents at low voltages such as Electrode Furnaces (similar to a welder).
In Tempest Computers which fell under the IEC950, the hard drives had to be made removable so they could be easily taken with during an invasion or destroyed in a giant shredder machine. The opening in the front of the computer gave the User access to a small backplane card and the data and power connectors for the hard drive. The backplane had to be limited to less than 240VA if the User could touch it. Fire was a completely different evaluation. My step dad was working on a car a got his metal watch band between the starter solenoid and the chassis. It instantly welded his watch to the car and turned the band into a glowing red hot heating element within a second. He was able to break it loose and get the watch off but not before he was badly burned. Almost required skin grafts. However, according to most safety standards, 12 volts at high current is NOT considered hazardous live and does not limit access to Users. Yes, it is a fire hazard but I don't think that is where the 240VA requirement comes from. Like the watch band, I have heard where people have reached inside of a piece of electronic gear and shorted out a circuit with their wedding ring. If this condition is possible, I believe the circuit would have to be limited to 240VA. This is my recollection of where 240VA came from and how it was used. I do not have any current documented support for it use today. But we still consider it for circuits accessible to the User to determine an Energy Hazard. The Other Brian -----Original Message----- From: Ralph McDiarmid [mailto:ralph.mcdiar...@schneider-electric.com] Sent: Wednesday, June 08, 2016 4:31 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] fire safety test methods for different country standards So, for the protection against FIRE, we have two energy rates, 100VA and 240VA, used across quite a number of standards, and the units are wrong. Should be Watts. Ralph McDiarmid Product Compliance Engineering Solar Business Schneider Electric *Please consider the environment before printing this e-mail -----Original Message----- From: Nyffenegger, Dave [mailto:dave.nyffeneg...@bhemail.com] Sent: Wednesday, June 08, 2016 1:27 PM To: Ralph McDiarmid <ralph.mcdiar...@schneider-electric.com>; EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] fire safety test methods for different country standards EN 60950-1:2006 2.5 uses 100 VA for LPS and is also referenced for fire enclosure requirements in section 4.7.2.1. -Dave -----Original Message----- From: Ralph McDiarmid [mailto:ralph.mcdiar...@schneider-electric.com] Sent: Wednesday, June 08, 2016 3:11 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] fire safety test methods for different country standards Hi Chuck, A poor choice of words on my part. I should have written, "in most of the standards I have worked in". Those include CSA107.1, UL1741, UL1012, and IEC62109-1 The 240VA (I think they meant 240W) must have come from some base standard as a normative reference. I don't know what is special about that number, but some committee somewhere may have concluded that power (rate of energy) below that threshold was unlike to be a source of ignition. I've seen 30V and 8A used to define an energy limited, extra-low voltage circuit. (UL calls that a Class 2 I think). The product of 8A and 30V gives 240VA as a third criterion. I'm not sure it's that simple though. Regards, Ralph McDiarmid Product Compliance Engineering Solar Business Schneider Electric *Please consider the environment before printing this e-mail -----Original Message----- From: Chuck August-McDowell [mailto:chu...@meyersound.com] Sent: Wednesday, June 08, 2016 11:22 AM To: Ralph McDiarmid <ralph.mcdiar...@schneider-electric.com> Subject: RE: [PSES] fire safety test methods for different country standards Hi Ralph, I live in the IEC/EN/UL 60065 standard world. Could you point at "most standards appear to limit rate of energy transfer (e.g. 240W)" standard? IEC/EN/UL 62368-1? IEC/EN/UL 60950-1? Thank you, Chuck McDowell Compliance Specialist Meyer Sound Laboratories Inc. -----Original Message----- From: Ralph McDiarmid [mailto:ralph.mcdiar...@schneider-electric.com] Sent: Wednesday, June 08, 2016 9:27 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] fire safety test methods for different country standards Not following instructions is foreseeable misuse and needs a FMEA and maybe a Fault Tree analysis too, if a hazard is the anticipated result. Getting back to this HB enclosure discussion earlier in this discussion thread, I see that most standards appear to limit rate of energy transfer (e.g. 240W) and may also place limit on available current. The expectation is, I think, that a power-limited device cannot ignite something. I assume there is lots of history that assumption. Ralph McDiarmid Product Compliance Engineering Solar Business Schneider Electric -----Original Message----- From: Richard Nute [mailto:ri...@ieee.org] Sent: Sunday, May 22, 2016 5:40 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] fire safety test methods for different country standards Hi John: Thanks for your additional comments. > Could it be that the scenarios which the standards committees envisage > are not "the real deal" In my opinion, this is the case. > OR that the > products which cause the fires just don't comply with the standards? Of course, counterfeit and non-complying products are in the marketplace. Some of these do catch fire. My interest is the cause of fires in products which comply with the standards. The "In Compliance" reports do identify the counterfeit products, but these seem to be in the minority. Fires occur under fault conditions. Not following instructions is a sort-of fault condition, but rarely the cause of a fire. 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