Project Spotlight: San Bruno Cable Pull

New River Electrical recently completed a unique cable installation in South San Francisco, California. This project was the first of this type in the country and consisted of replacing a pipe-type cable with a tri-plexed solid dielectric cable in the same pipe.

Nine IBEW members from New River Electrical Corporation’s Underground Transmission division performed the project. The crew worked hard to make sure everything ran efficiently and incident-free on this complex project.

The Complexities of a Cable Pull

We installed a tri-plexed 115,000-volt circuit that consisted of three separate XLPE cables tri-plexed at the manufacturer’s plant together with one groundcontinuity cable (GCC), making a total of 7.5 inches in diameter. The cable was then installed into an 8-inch steel pipe that was originally used as part of a pipe-type cable installation .

“A fiber optic cable installed inside the hollow pipe within the cable bundle helps monitor the temperature of the high voltage cable while energized to show any hot spots or abnormalities,” said Jared Hurley, General Foreman on the project.

A wooden mandrel, one-half inch smaller than the diameter of the pipe, was then pulled through end-to-end along with two 8-inch foam swabs to assure the pipe was properly cleaned and free of debris or foreign objects.

“We use the wooden mandrel to mimic the outside surface of the high voltage cable jacket,” said Hurley, “so if the mandrel is damaged while pulling through the pipe, we’ll know that the cable would be damaged as well.” Additionally, the wooden mandrel helped to assure the pipe was not oval shaped or collapsed at any point and that the required bending radius had not been violated.

Before and after cable installation, we are required to perform a 10,000 to 25,000-volt DC test on high-voltage cables in order to ensure that the cable had not been damaged during shipping from the manufacturer or during the installation.

Once our crew assured the pipe was clean and defect-free and the high-voltage cable had been tested, the 20,000-pound winch line was then used to pull the cable. The process was monitored by sensors built into the equipment that record the speed and tension for the entire length of the cable pull.

In total, the cable pull for this project was 1,097 feet from end to end.

Our Commitment to a Job Well-Done

Our workers’ safety is paramount at New River Electrical Corporation. We provide proper personal protective equipment, extensive training, and conduct safety meetings weekly, as well as job site analysis and audits daily.

The result of this significant project met the goals set by Pacific Gas and Electric Company (PG&E) and was delivered by a team of experts including Black & Veatch Construction Inc. (BVCI) as the EPC Prime Contractor, and Sumitomo Electric Industries (SEI) as the Cable System design and manufacturer.

Our team is not only proud of the successful completion of this leading-edge cable installation, but most importantly, that it was performed effectively and without incident.