Thanks to all who replied to my email. I was expecting reassurance that my understanding of this topic, going back some 25 years, still holds true. But once again, it appears as if things are changing without my knowledge which really makes for a bad day. I really hate it when I have to tell engineering I was wrong.
Though it appears that using the |/O symbols on switches other than the disconnect device is a violation of IEC/EN 61010-1 Ed. 2, other standards seem to contradicts this. Does anyone have a pre-release version of the IEC 61010-1 Ed. 3 to see what it says on this topic? The IEC 60934 standard for Circuit Breaker (including those with switches) states that the switch must be marked with the |/O symbols. It says nothing about disconnect device. "For CBEs other than those operated by means of push-buttons, the open position shall be indicated by the symbol "O" and the closed position by the symbol "I" (a short vertical straight line).” This is why our circuit breaker vendor is saying our breakers must have the |/O symbols regardless of their use. The following UL60950 Guideline document recommends using the |/O symbols on ALL switches to show the On/Off position. (thanks to Sylvia for sending this to me) http://data.ul.com/pagos/access/60950/1783003.asp “UL60950: Per 3.4.8, switches and controls which are considered the main disconnect device shall be marked "|"/"O". Also, if a switch is located in the primary and it affects safety, e.g. it controls hazardous moving part, it shall be marked "|"/"O". Other switches which do not affect safety, including primary and secondary controls, do not need to be marked "|"/"O", although this is the preferred method of indicating on and off positions.” So if the |/O symbols can be used on switches other than the Disconnect Device, then how are you to identify the Disconnect Device? Is there an international symbol for Disconnect Device? If not, maybe there should be. Thanks again to all. The Other Brian ________________________________ From: [email protected] [mailto:[email protected]] On Behalf Of Kunde, Brian Sent: Wednesday, February 24, 2010 1:06 PM To: emc-pstc Subject: Use of | and O symbols Reference IEC/EN 61010-1 2nd Ed. Safety Standard. Our product is considered Laboratory Equipment. The | and O symbols are on our Mains Supply Switch/Breaker which is also our Disconnect Device, but engineering wants to use additional switch/breakers (functional purpose) to power on/off different sections of the product. The switch/breakers they want to use are breaking AC Mains to sections of the product and have the | and O symbols printed right on the switches. It has always been my understanding that the | and O symbols can only be used on the Disconnect Device which cuts AC mains to the entire product. Can the | and O symbol also be used on other AC Main switch/breakers that cut AC Mains Supply power to only sections within the product but not the entire product? In our case, these additional switch/breaker cut AC mains to circuits but there are other circuits in the same section that are still powered up. The purpose of these additional switches are to power down sections or devices for power savings at night when some sections of the product need to stay on 24/7. One last detail; all the switch/breaker including the Disconnect Device switch are all physically mounted on the same panel right next to each other, so I am concern with the proper identification of the Disconnect Device switch. Other than the | and O symbol, are there other ways to identify the Disconnect Device switch? The manufacturer of the switch/breakers will not make it without the | and O symbols without loosing its VDE certification. I’ve been telling engineering that the | and O symbols can only be used on the Disconnect Device. Am I wrong? The standard says, “Symbols | and O shall not be used for switches other than the power supply switch.”, however, section 5.1.6 says, “If the power supply switch .. is used as the disconnecting device…”, implies that a power supply switch does not have to be the Disconnect Device. Please help clarify this circular logic for me. The Other Brian PS: Here is the entire section 5.1.6 to use as a referrence: 5.1.6 Switches and circuit-breakers If the power supply switch or circuit-breaker is used as the disconnecting device, the on-position or the off-position shall be clearly marked. Symbols 9 and 10 of table 1 can, in some cases, also be suitable as the device identification (see 6.11.2.5). A lamp alone is not considered to be a satisfactory marking. Symbols 9 and 10 shall not be used for switches other than the power supply switch. 6.11.3.1 Switches and circuit-breakers An equipment switch or circuit-breaker employed as a disconnecting device shall meet the relevant requirements of IEC 60947-1 and IEC 60947-3 and be suitable for the application. If a switch or a circuit-breaker is used as a disconnecting device, it shall be marked to indicate this function. If there is only one device – one switch or one circuit-breaker – symbols 9 and 10 of table 1 are sufficient. A switch shall not be incorporated in a MAINS supply cord. A switch or circuit-breaker shall not interrupt a protective earth conductor. A switch or circuit-breaker with contacts for disconnecting and other contacts for other purposes shall conform to the requirements of 6.6 and 6.7 for separation between circuits. 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