In previous Items of Engineering Interest, we have discussed testing of new underground cable. The Underground Subcommittee of the NRECA’s T&D Engineering Committee highly recommends that electric utility operators test underground cable they purchase. The Subcommittee recommends that the following tests be conducted at a minimum.

1. Dimensional analysis of all cable components;
2. Microscopic examination for voids, contaminants and protrusions; and
3. Insulation shield stripping test.

The Subcommittee also recommends that optional testing of Tree-Retardant Cross-Linked Polyethylene and Cross-Linked Polyethylene insulated cables include a Hot Oil Test. The Subcommittee does not recommend conductor shield and insulation shield resistivity tests because they consistently test well below maximum specifications.

Subcommittee recommended typical sampling rates are to test one sample, each, from the first and last reel on orders of 50,000 feet (15 km) or less and one sample for each additional 50,000 feet (15 km) of cable ordered.

The Subcommittee recommends that purchasers instruct manufacturers to cut samples and send them to the selected testing laboratory, or the purchaser can cut the samples upon arrival of the shipment. The Subcommittee further recommended that purchasers notify suppliers in advance that cable testing will be conducted and purchasers should establish responsibilities and procedures in case of a failure, such as: Any evidence of noncompliance with the enclosed specifications shall be justification for:

1. Further testing at manufacturer’s expense (each shipping reel);
2. Rejection of the tested reel and possibly the reels preceding and following in the manufacturing process; and
3. Rejection of the entire order, depending on the severity and frequency of noncompliance.

A partial list of possible independent testing laboratories provided by the Subcommittee includes:

Cable Technology Laboratories, Inc.
P.O. Box 708
690 Jersey Ave.
New Brunswick, NJ 08903
(201) 846-3220

Forster Electrical Engineering, Inc.
550 North Burr Oak Ave.
Oregon, WI 53575
(608) 835-9009

NEETRAC
62 Lake Mirror Road, Building 3
Forest Park, GA 30050
(800) 762-6522

All of these laboratories participate in the Cable Acceptance Testing Program promoted by NRECA’s T&D Underground Subcommittee. The inclusion of a laboratory in this list does not imply endorsement by RUS. The testing laboratories listed above have voluntarily agreed to collect electric cooperative test data and provide it to the NRECA Underground Subcommittee annually for information and publication. To have your data included, note on your purchase order "INCLUDE IN COOPERATIVE DATA FILE." Cooperative names will not be published and participation is voluntary.

If you would like more information or have any questions, please call Trung Hiu, Electrical Engineer, Distribution Branch, at (202) 720-1877.