Use stress cones at each end of all phases
of jacketed URD cables.
Don't use porcelain.
One major manufacturer is Joslyn in Chicago.
They manufacture at least several, and have printed
instructions on how to install.
We use 3M Quickterms, because they are inexpensive and
fast to install.
Make certain you install MOV surge arresters (Ohio Brass) at both ends of your cable(s) as well.
URD cable can be a big headache......try to use EPR, not
XLPE-TR. XLPE-TR will 'water tree' within 18-20 years....inherent to the cable. EPR will go for 40 or more
years.
Also, make certain the cable insulation thickness is %133, and has a jacketed neutral. For single-phase residential feeders, use a full-neutral. Substation getaways: use 1/3 neutral.
I don't like to make contradictory posts but, we've been using XLPE cable for over 40 years and haven't had cable failures until about 40 years of age and the cable is installed under the water table. And that is straight XLPE. We are now using the enhanced Tree Retardant XLPE (TR-XLPE) and expect only better results.
Experience seems to have a greater effect on MV-cable life compared with 600-volt materials. There is a lot less room for error with shielded-cable installation. 65kVDC testing of new 15kV 133% cables does a good job of ‘flushing out‘ sloppy splices and terminations.
