| Alternative | New Constr. cost relationship | Retro Fit Issues | Operational Issues | Safety Considertion | Net effect on Reliability | Impact on Trees |
|---|---|---|---|---|---|---|
| OH Wing Arm | 100-105 | Requires sufficient conductor slack. May require additional guying | Access from pole reduced, may require use of a bucket truck | No significant difference | No Significant difference | Clearances change spacially (+ or -4 ft.) |
| OH Re-route | 105-125 | Requires new pole, additional conductor, and guys | No significant difference | No significant difference | Reduction or elmination of tree related conflicts | Elimation or conflict shift to alternate site? |
| OH Compact Configuration | 95-110 | Electical clearance codes may require new poles. Shorter spans | Reduced phase spacing can restrict working clearances | Reduced working clearances | Can result in reduced reliabilty due to phasephase outages | Potential reduction in total crown area affected due to tighter spacing |
| Covered OH primary a.k,a. “Tree Wire’ | 110-120 | Increased mechanical loads may require hardware/pole upgrades | Work practices such as use of working grounds are more difficult. Requires regular patrols. Coating requires increased work for splices and taps | Reduced ability of system protection to detect downed and energized conductors. Presents a risk to public safety. | Reduction in branch failure caused phasephase faults. | Not considered a means to eliminate line clearance tree work. |
| Aerial Spacer Cable a.k,a. “Hendricks System” | 120-200 | Increased mechanical loads likely to require some hardware and pole upgrades. | Dramatically reduced phase spacing and conductor coating may increase working difficults. Requires regular patrols. Covering requires increased work for splices & taps | Reduced ability of system protection to detect downed of energized conductors. Heavy conductor covering reduces potential risk. | Significant reduction in branch failure caused phase-phase faults | Reduction in total crown are affected due to tighter spacing Debate over reductions in clearance required |
| Aerial Cable (true cable) | 200+ | Increased mechanical loads will require significant hardware and pole upgrades | Insulation requires increased work for splices and taps. Work it like UG cables. May require outage to make taps. | Reduced ability of system protection to detect downed & energized conductors. Rated insulation reduces risk of adverse effect on public safety | Dramatic reduction in branch failure caused phase-phase faults | Reduced clearance requirements. More a mechanical than electircal clearance issue. |
Cost relationship is provided as a general relative cost. No cost units are implied. The intent is to provide a comparative cost reference. All values are stated as related to bare overhead 3 Ø distribution primary (100)