Gents, This is a very timely discussion as some of this has come up as a topic of discussion for me in just the last couple days. Specifically regarding the yellow background. My question is:
* Must the background be yellow, or can it be any color as long as it provides strong contrast with the red button? Someone suggested blue as a background color because allegedly this is easier for color blind persons to see. What standard(s) does this requirement come from? Thanks, Mark Mark Ortlieb Sr. Product Safety Engineer 858-207-7591 Brain Corporation™ 9401 Waples Street, Suite 100<https://maps.google.com/?q=9401+Waples+Street,+Suite+100+San+Diego,+CA%C2%A0+92121&entry=gmail&source=g> San Diego, CA<https://maps.google.com/?q=9401+Waples+Street,+Suite+100+San+Diego,+CA%C2%A0+92121&entry=gmail&source=g> 92121<https://maps.google.com/?q=9401+Waples+Street,+Suite+100+San+Diego,+CA%C2%A0+92121&entry=gmail&source=g> www.braincorp.com<http://www.braincorp.com/> From: "Doug Nix, C.E.T." <d...@ieee.org> Reply-To: "Doug Nix, C.E.T." <d...@ieee.org> Date: Wednesday, April 24, 2019 at 10:16 AM To: "EMC-PSTC@LISTSERV.IEEE.ORG" <EMC-PSTC@LISTSERV.IEEE.ORG> Subject: Re: [PSES] E-Stop Questions Hi Brian, I’ve dealt with many related questions on my blog, machinerysafety101.com<http://machinerysafety101.com> https://machinerysafety101.com/series/emergency-stop/, but not these specific questions, so I’ll answer them now. Then I’ll add them to the blog (thanks for the inspiration!). 1) How mushroom-shaped is enough? There’s no hard answer to this, but I can say this: there are three fundamental shapes for push button operators, flush, extended, and mushroom. The intent is that neither flush nor extended head operators be used for e-stop functions. More info in IEC 60947 on that. 2) Yellow background. Yellow backgrounds have to be big enough to provide clear contrast with the red button operator. A tiny ring, or just a yellow stripe around the base of the button is not enough in my opinion. Typical rings are 2x the operator nominal size, i.e., 30 mm buttons get a 60 mm ring, 22 mm buttons get a 44 mm ring. These are common practice recommendations. 3) Printing “emergency stop” on the yellow ring is not required in any jurisdiction anymore, and has been removed from NFPA 79, as well as IEC 60204-1. Just leave it off, as the red/yellow combination is internationally recognized as the sign for e-stop and emergency switching off devices. Best, Doug Nix d...@ieee.org<mailto:d...@ieee.org> Mobile: (519) 729-5704 Office:(519) 650-4753 On Apr 24, 2019, at 12:49, John Woodgate <j...@woodjohn.uk<mailto:j...@woodjohn.uk>> wrote: Mushrooms come in all sorts of shape, so the description is not very scientific. It's only a concern if the AHJ thinks it is! Whether the English is acceptable is a matter for national legislation, so there are probably several incompatible answers. Best wishes John Woodgate OOO-Own Opinions Only J M Woodgate and Associates www.woodjohn.uk<http://www.woodjohn.uk> Rayleigh, Essex UK On 2019-04-24 17:43, Brian Kunde wrote: I am constantly being asked three questions about E-Stops which I cannot find the answers to. 1. "Mushroom Shape" is specifically called out in some standards but the newer style e-stop switches are becoming less and less Mushroom Shaped. If this a concern? 2. "Yellow Background" is getting smaller and smaller. Some small e-stop switches has no yellow background but has a small area on the shaft of the switch that is yellow. This is not technically the "background". Is this acceptable or is a yellow background required in addition? The size of the yellow area is not specified as far as I have found. 3. English text "Emergency Stop" printed on the button or on the yellow background ring: Is this a problem in non-english speaking countries? Do I have to translate (like in French for France and Canada) or are these words "globally acceptable"? I have been telling our engineers to choose e-stop switches and yellow rings without text but some manufacturers only provide it with the text. Thanks to all. The Other Brian - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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