I first posted this on the general forum but figured I get more help here.
This is a question I had on a tap rule quiz I gave my apprenticeship students: "You have an outside feeder tap running between two buildings. The tap conductors are copper tri-plex cable attached to a chain link fence at a height of 7'. Legal or illegal and code ref". We all know it's illegal, that's not the issue. The issue was the section. Specifically: 240.21B51 makes it illegal because they are not "suitably protected from physical damage" Two of the students sited 230.50B and said this would apply even without the tap rule. I don't know if 230.50B would apply to a tap or is it for a (protected) feeder or what. So ... what do you think: would 230.50B make this illegal?
Questions like this should not be on a test. What is "protected from physical damage" is not well defined in the code and is usually the inspectors call. If this cable was a 7' 1" would it be protected? How about 8', or 10'? Is there any guarding on the fence? Questions like this need to explicitly tell you if the conductors have been deemed to be subject to physical damage or severe physical damage or not subject to damage. There are only a few places in the code where you're explicitly told that a conductor of size X is OK even if subject to (severe) physical damage.
Mark Kent, WA
Re: Outside tap (240.21 vs 230.50)#92805 04/11/0505:33 AM04/11/0505:33 AM
iwire: This is a hypothetical. By telling them it's an outside feeder tap I'm trying not to have them make the determination if it is that type tap. My goal was to see if they knew that any cable mounted only 7' high on a fence would not be considered protected (unless they had an extremely liberal AHJ). We try to teach the "average man" rule in cases like this. If the average man could do something with little or no effort than it's considered doable. In this case doable means reachable and it's subject to damage by anything that man is carrying and hazardous to the curious kids climbing the fence (same principle as the point of attachment of the drop needing to be 10' above finished grade). They threw me for a loop when they looked up 230 instead of the outside feeder tap rule.
Re: Outside tap (240.21 vs 230.50)#92806 04/11/0505:35 AM04/11/0505:35 AM
mark: I disagree on the quality of the question. However; if they would have sited their section and said what you just said I'd have passed them in a heartbeat. I only wish my students had enough knowledge of the NEC to question it.
Re: Outside tap (240.21 vs 230.50)#92807 04/11/0502:07 PM04/11/0502:07 PM
That approach would be OK if the student can provide a written answer and knows that if he qualifies his answer he can still get credit. So many tests are multiple choice now, that you don't always know what assumptions the test writer was making or which ones you're supposed to be making.