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Hi All, I am pretty new at electrical design for PLC control panels. We are a UL508A shop, so this is the code I refer to most. Something struck me as odd when I was trying to size wire for this control panel. UL508A 28.3.1 says this: The required size of the field wiring terminal shall not be less than 14 AWG (2.1 mm2) and shall be determined by: a) Calculating the required ampacity per 28.3.2 – 28.3.6; and b) Determining the minimum field wiring conductor size from Table 28.1 having a corresponding ampacity that is equal to or greater than the required ampacity from (a). How can the minimum wire size be #14 AWG? We use #16 AWG for wire to the PLC modules? Are we breaking code or is there something I am missing? Also, understanding code books can be difficult. Is there a website or place I can go to get a plain English translation? I feel like I will read a sentence over and over again to try to understand what they are saying, and feel like there's is a much easier way to say it than the way it is written. For example, "28.3.1 b" ……...what is it really saying?
bboytaktix posted a topic in Allen BradleyGood afternoon Mr.PLC forum members. We recently had a fuse blow on the wiring between a 1756-OF6CI analog out card and a control valve (which we have no feedback for - only the 0-100% output). Took a little longer to troubleshoot since we have no feedback and we also don't monitor individual channel status of the card. For input cards (1756-IF8H or IF16H), it's easy enough to use the under-range/over-range or broken wire signal to troubleshoot a blown fuse or bad connection, and activate an alarm. I have been told by our local consultant-technician that there is an equivalent monitoring bit for output cards. Reading the instruction manual for the 1756-I/O cards, the fault channel bits do not seem to have this type of function for the 1756-OF6CI. The fault bits only seem to look at the requested output values, and at the connection between card and PLC itself as far as I can tell. Am I missing something? thanks for your help