The tape method was the only way to make a good splice until shrink tube splice kits became available. Many installers still use tape because it has worked for them for years. You crimp the conductors together, wrap each conductor with a layer of rubber tape followed with a layer of plastic electrical tape. This makes a watertight connection and insulates the conductors from each other and the well casing. Properly done, this technique makes an excellent splice, but is very time consuming.
This multi-purpose rubber insulating tape is used as a primary tape insulation in splicing and terminating wires and cables rated up to 90ºC / 194ºF. It is a highly conformable, linerless Ethylene Propylene Rubber (EPR)-based tape. 3/4 in x 15 ft $6.00
PVC 3/4" X 60' Black Electrical Tape Scotch # 1700 (A)
Scotch Temflex model 1700 black PVC insulating electricians tape. 7 mil thick x 3/4" wide x 60ft. long roll. UL listed. CSA certified for 176°F. Weight: 0.24 lbs. $1.00