For those who have been following this story, the (mis)adventure continues. :weeping:
Brief backstory: As part of our 1MW solar project 19 months ago, the installing contractor pulled our existing (16) 500 MCM aluminum main feeder wires (480V/1,000A, 3-phase wye) into two in-ground conduits, damaging the insulation in the process. Two months ago, one conduit shorted out (destroying all wires within) and the other conduit was tested as having three damaged wires. After threats of legal action, the contractor finally agreed to replace the feeders. We opted to switch from (16) 500 MCM aluminum wires in two conduits, to (8) 400 MCM copper wire in one conduit (derating our service from 1,000A to 600A); we agreed to pay the $10K cost difference for this new copper XHHW wire. The contractor wanted a more experienced and skilled crew to do the new pulls, so he subbed the wire pulling part of the job to another contractor; the original contractor made the splices at the in-ground pull box.
The job was done last Friday. The wire was installed in two separate pulls: a 200' section from the distribution panel to the mid-point in-ground pull-box, and a 160' section from the switch gear to the pull-box. The wire was spliced at the pull-box. Before putting the feeders in service, we had an independent testing company perform insulation resistance tests on all the replaced wires (which, btw, the contractor objected to). One of the eight new 400 MCM copper wires tested low resistance to ground (~50K ohms). The splice at the mid-point pull-box was cut and the two sections of wire tested separately. Each section tested bad. Both the contractor and sub-contractor are of the opinion that the wire was defective from the distributor based on the fact that when they cut the splice out, they discovered a light coating of black oxidation on the copper wire's strands suggesting that water had intruded into the wire before it was sold.
Because the work was scheduled on a Friday, our options to resolve the problem were limited. The contractor's immediate "fix" was to change this wire from being a 480V phase conductor to being a neutral conductor, which we agreed would be an acceptable short-term solution. The contractor is currently discussing the problem with the wire distributor, but so far has not made any arrangements to replace the wire. In fact, so far he has not even conceded that the wire should be replaced. Based on comments made Friday, our expectation is that he will try to justify leaving the wire as-is and calling the job completed.
Questions:
1. Is it code-compliant to have a neutral feeder in service that has failed insulation resistance testing?
2. If it is not prohibited, what are the long-term issues with using this wire as a neutral inside buried conduit filled with brackish water?
3. If you were the customer who had paid for the installation of new copper wire, would you be willing to accept this damaged feeder?
Brief backstory: As part of our 1MW solar project 19 months ago, the installing contractor pulled our existing (16) 500 MCM aluminum main feeder wires (480V/1,000A, 3-phase wye) into two in-ground conduits, damaging the insulation in the process. Two months ago, one conduit shorted out (destroying all wires within) and the other conduit was tested as having three damaged wires. After threats of legal action, the contractor finally agreed to replace the feeders. We opted to switch from (16) 500 MCM aluminum wires in two conduits, to (8) 400 MCM copper wire in one conduit (derating our service from 1,000A to 600A); we agreed to pay the $10K cost difference for this new copper XHHW wire. The contractor wanted a more experienced and skilled crew to do the new pulls, so he subbed the wire pulling part of the job to another contractor; the original contractor made the splices at the in-ground pull box.
The job was done last Friday. The wire was installed in two separate pulls: a 200' section from the distribution panel to the mid-point in-ground pull-box, and a 160' section from the switch gear to the pull-box. The wire was spliced at the pull-box. Before putting the feeders in service, we had an independent testing company perform insulation resistance tests on all the replaced wires (which, btw, the contractor objected to). One of the eight new 400 MCM copper wires tested low resistance to ground (~50K ohms). The splice at the mid-point pull-box was cut and the two sections of wire tested separately. Each section tested bad. Both the contractor and sub-contractor are of the opinion that the wire was defective from the distributor based on the fact that when they cut the splice out, they discovered a light coating of black oxidation on the copper wire's strands suggesting that water had intruded into the wire before it was sold.
Because the work was scheduled on a Friday, our options to resolve the problem were limited. The contractor's immediate "fix" was to change this wire from being a 480V phase conductor to being a neutral conductor, which we agreed would be an acceptable short-term solution. The contractor is currently discussing the problem with the wire distributor, but so far has not made any arrangements to replace the wire. In fact, so far he has not even conceded that the wire should be replaced. Based on comments made Friday, our expectation is that he will try to justify leaving the wire as-is and calling the job completed.
Questions:
1. Is it code-compliant to have a neutral feeder in service that has failed insulation resistance testing?
2. If it is not prohibited, what are the long-term issues with using this wire as a neutral inside buried conduit filled with brackish water?
3. If you were the customer who had paid for the installation of new copper wire, would you be willing to accept this damaged feeder?
