![]() Quite possibly the contractor felt that it would be cheaper to just use the proper cable than to argue with you and/or the AHJ. You may have slightly higher touch potentials. If this were to be installed under the 2015 edition of the Canadian Electrical Code you would require a #3 AWG conductor to be run in close proximity to each group of 500 MCM conductors. In the case of parallel feeders, The 2015 edition of the Canadian Electrical Code now requires the grounding conductor to be run in parallel also. If we consider the two 500 MCMs to be the equivalent of one 1000 MCM then a #1 AWG cable would be required. The 2015 edition of the Canadian Electrical Code sizes the main bonding jumper based on the size of the service conductors. ![]() The ampacity of parallel 500 MCM exceeds 800 Amps so 2/0 cable would be required. The 2012 edition of the Canadian Electrical Code sizes the main bonding jumper based on the ampacity of the service conductors. Note I don't suggest ignoring the code, however the question has to do with the safety of the installation. That question is more interesting than I first thought. This is a mistake that I surely won't be making in the future.īest Regards RE: Undersized Grounding Electrode Conductor waross (Electrical) 2 Mar 16 13:47 The project is already built and the contractor may have picked up on the mistake, but I needed some peace of mind on this question. I know that having an undersized grounding electrode conductor can lead to the possibility that when there's a fault current, the cable could burn up when transferring the fault current to the grounding electrode, but I wanted to know if being off by one size (1/0 instead of 2/0) poses a huge compromise to safety or if the 1/0 would be able to handle most fault current situations. Instead of using a 2/0 wire I used a 1/0 for my grounding electrode conductor size as well as my main bonding jumper. When I went to size the grounding electrode conductor, I accidentally sized it for only one set of 500 kcmil using table 250.66 in the NEC. The project had an 800 amp main distribution panel with two sets of 500 kcmil for the service entrance. The other day I noticed on one of my previous projects that I undersized my grounding electrode conductor and main bonding jumper. I am an engineer in training and relatively new to this field, so I am still learning on a daily basis. This is my first time posting to this forum and I had a question that I've been obsessing about for about a week now.
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