I recall that IEC61010-1 allows you to demonstrate through application of a sufficient number of component single-faults that openings can be larger than those required for a fire enclosure. I think the premise is that if you demonstrate that a fire can’t start, you don’t need to apply the strict rules a fire enclosure imposes. ( I recall a flowchart in the section about protection from fire hazards)
Ralph McDiarmid, AScT Compliance Engineering Group Xantrex Technology Inc. From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Friday, May 22, 2009 7:00 AM To: [email protected]; [email protected] Subject: RE: IEC 61010-1 safety standard question Hi Peter: A couple of quick points from my perspective. Note that in figure 6 (61010-1, second edition) the baffle overlap distance needs to be a least 1 inch ("Y = twice X but never less than 25 mm"). This can work for larger pieces of equipment, but can be difficult in smaller equipment. Figure 7, the 5° angle, is part of clause 9 (Protection against the Spread of Fire), therefore is only applicable to circuits which do not qualify as a "Limited-Energy Circuit" per clause 9.3. In my opinion, the intent of the requirement is that if openings in the enclosure are below or within the 5° angle of applicable circuits, it does not matter whether they are on the side or the bottom, the requirements apply. Unfortunately, it is not clear in the text how the requirement applies to slots. You may want to look in 60950-1 (see clause 4.6) where there are similar requirements and perhaps it will give you some further guidance. In addition, you may also want to take note of the 2 mm dimension in clause 9.2.1 b) 1). That may be useful if you are going to be proposing some rationale to some certifying organization. That's all just my opinion. Not sure if that helps or hurts. Good luck. Richard Richard Payne Tektronix, Inc. Product Safety Engineering V: (503) 627-1820 F: (503) 627-3838 E: [email protected] From: [email protected] [mailto:[email protected]] On Behalf Of Peter Sent: Tuesday, May 19, 2009 12:22 PM To: [email protected] Subject: Re: IEC 61010-1 safety standard question Hi Guys, Thank you for your input :-) Yes - i understand that the issue is to prevent dripping melted plastics. However as far as i read figure 7 drawing, there is no requirements on the sides but only bottom is this true ? The device has no openings at all in the bottom so projection of 5 degrees >from possible meltable parts is no problem. Below is my second try to draw enlarged part of the chassis corner, the outer panel part is screwed onto the the side part. Front of device --> | | | | ___________________ | | | | | <-2mm-> | <-- side part --> | |_________| |____________Bottom_____________ Hope this is clearer (corner is similar in all four corners of the bottom) ? What i cannot figure out is do i have a potential problem having this 2mm slot in the corners where material gathered in the bottom could drip from ? Though i think the 2mm gap should be no larger than the suggested baffle design mentioned in the standard. Have a nice day all :-) Best regards Peter ----- Original Message ----- From: ce-test, qualified testing bv - Gert Gremmen <mailto:[email protected]> To: Peter <mailto:[email protected]> Sent: Monday, May 18, 2009 7:58 PM Subject: RE: IEC 61010-1 safety standard question I do not see an gap in your drawing ?? In general the hole problem, is related to the risk of melted burning plastics leaking out. Limiting the holes to 1mm wide and/or 5mm round (I believe) prevents the leaking. Gert Gremmen Van: [email protected] [mailto:[email protected]] Namens Peter Verzonden: maandag 18 mei 2009 19:34 Aan: [email protected] Onderwerp: IEC 61010-1 safety standard question Hi experts, A question about the IEC 61010-1 requirements to the bottom (and sides) of a device cases fire enclosure. With regards to the bottom there are well explained rules for the design of the bottom in 9.2.1 Constructional Requirements. I have a device with completely flat bottom without any holes, front and back is bended 90 degrees to make sides of front/back in the two other sides there is a small bend up side panel of 22mm all this is formed out of same plate. Now my question is related to the corners where the front/back panels meet the small side panels all bent upwards, here there is a small gap of 2mm bewteen the materials. It´s not exactly the bottom but instead in the side so do i have a problem or will it be OK ? | |2mm | | __________________________ | | | front | | | | |_| |______Bottom of device________ I tried to make a drawing (best seen using non proportional font) Hope this is somewhat clear, have a nice day :-) Best regards Peter - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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