I am hoping some of the veterans out there can give me some insight and there experiences on the use of DLO (UL listed of course) for use as building wire. The application requires large conductor sizes and some pretty tight bending radius that would make it next to impossible to install with traditional methods. The AHJ approved the design with DLO, but now they want it torn out. How have you guys resolved the following issues in the past with the AHJ:
1. The DLO in question is UL listed as a RHW/RHH-2 cable and CT rated. Has anyone ever encountered a restricted UL label such DLO label for RHW/RHH-2 is only applicable under certain conditions? My current argument is if its is UL labeled as RHW/RHH-2 it complies with Article 310, it is allowed for use as noted within NEC Chapter 3 (NEC 310.13).
2. Once you get above 4/o the conductor sizes get “oddball”. My design as approved interpolated between conductor sizes per the 310 Tables (i.e., 535.3MCM on Table 310.17, 75degC is 620A). Has anyone else used this methodology or did they just round down to the next published conductor size? Or has anyone tried a NEC 310.15(C) supervised calculation?
3. This one surprise me since the original design complied with NEC 392.11(B)(3), but when the Owner threw another feeder into the mix during construction that Code section was kaput (lucky me). Now if I specified 535.3MCM, how do you resolve 392.11(B)(1) and (2)? Average the 2 conditions or throw more copper into the project and just comply with 392.11(B)(2)?
4. Does anyone know of any UL486 or NEC nuances that says you cannot use a Class DLO or equivalent highly flexible, stranded cable termination for general wiring. I am just asking to have an answer for the AHJ in case they ask, because I can already see an argument that the terminations for DLO are only for a NEC 400 cord connection and not a NEC Chapter 3 installation, or that the UL listing is only good for factory assembled equipment.
I have specified DLO in the past without any problems (knock on wood) but this current project has thrown all kinds of problems that I thought I had reasonably resolved in the past. Things have been fairly diplomatic so far and the last thing I want to have happen is have the AHJ use the infamous NEC 90.4 triumph card and me becoming an engineer who knows where you can get a great deal on some DLO cable :smile:
Any insight and/or experiences will be greatily appreciated by this EE.