This may seem like a stupid question, but I'm looking for NEC clarification. Bear with me, this info was brought to me second hand so the details may seem a little sketchy.
One of our electricians is working on a school project. They are installing EMT to feed a couple of different loads, a lighting circuit (15A) and a receptacle circuit (20A). Both are supplied from the same panel.
The blueprints call for two separate equipment grounding conductors. One for each circuit. A #14 for the lighting and a #12 for the receptacle circuit. The electrician did submit an RFI and was told this was how it was to be installed but was not told why. The receptacles being fed also are not Isolated Ground Type.
In the NEC I was unable to find any section that specifically prohibits the use of two separate EGC's in the same conduit. But I was taught that using two equipment grounding conductors in the same circuit would cause additional impedance in the grounding circuit, hence, causing the OCPD to operate slower under ground fault conditions due to the increased impedance of the circuit. This would seem like an unsafe practice to me, but cannot find any specific code section that prohibits this practice.
I know 250.122(C) describes using a single EGC for multiple circuits. This is the method that I have always used.
Can anyone tell me if the practice of using multiple EGC's in the same conduit is prohibited by the NEC. If so, what section? And also what your personal belief is of using this practice.
One of our electricians is working on a school project. They are installing EMT to feed a couple of different loads, a lighting circuit (15A) and a receptacle circuit (20A). Both are supplied from the same panel.
The blueprints call for two separate equipment grounding conductors. One for each circuit. A #14 for the lighting and a #12 for the receptacle circuit. The electrician did submit an RFI and was told this was how it was to be installed but was not told why. The receptacles being fed also are not Isolated Ground Type.
In the NEC I was unable to find any section that specifically prohibits the use of two separate EGC's in the same conduit. But I was taught that using two equipment grounding conductors in the same circuit would cause additional impedance in the grounding circuit, hence, causing the OCPD to operate slower under ground fault conditions due to the increased impedance of the circuit. This would seem like an unsafe practice to me, but cannot find any specific code section that prohibits this practice.
I know 250.122(C) describes using a single EGC for multiple circuits. This is the method that I have always used.
Can anyone tell me if the practice of using multiple EGC's in the same conduit is prohibited by the NEC. If so, what section? And also what your personal belief is of using this practice.