EWT - Testing and Test Facilities

The Occupation Safety & Health Administration (OSHA) states that, “In 1999, for example, 278 workers died from electrocutions at work, accounting for almost 5 percent of all on-the-job fatalities that year, according to the Bureau of Labor Statistics (BLS). What makes these statistics more tragic is that most of these fatalities could have been easily avoided.”

Utility and electrical workers are periodically tasked with testing important equipment that supports the electrical grid infrastructure, to keep operations running smoothly and prevent failures of the system. Here we’ll walk you through some basic guidelines to follow when working in testing facilities and testing certain equipment, suggested by the Occupational Safety & Health Administration (OSHA).

First, appropriate engineered controls provide the primary layer of safety for personnel; permanent test areas must be guarded by walls, fences, or barriers designed to keep employees out of the test area.

In field testing, or at a temporary test site where permanent fences and gates are not provided, one of the following means must be used to prevent unauthorized employees from entering: (1) the test area is guarded by the use of distinctively colored safety tape that is supported approximately waist high and to which safety signs are attached; (2) the test area is guarded by a barrier or barricade that limits access to the test; (3) or the test area is guarded by one or more test observers stationed so that the entire area can be monitored.

Guarding is provided within test areas to control access to test equipment or to apparatus under testing that may become energized as part of the testing. Barriers are removed when the protection they provide is no longer needed.

Safe grounding practices must be used at the test facility. Workers must maintain all conductive parts accessible to the test operator at ground potential, except for portions of the equipment that are isolated by guarding. Workers should treat ungrounded terminals of test equipment or devices under testing as energized until tests determine the equipment is de-energized.

The work team should apply visible grounds to the high-voltage circuits after they are de-energized and before work is performed on the circuit, item, or apparatus under test. Common ground connections must be solidly connected to the test equipment and the apparatus under test.

In high-power testing, an isolated ground-return conductor system must be provided. The two exceptions to this requirement are:

• An isolated ground-return conductor cannot be provided due to the distance of the test site from the electric energy source, and;
• Employees are protected from any hazardous step and touch potentials that may develop during the test.

If test equipment cannot be grounded by means of the grounding conductor located in the power cord, workers should secure a ground that affords equivalent safety, and clearly indicate the safety ground in the test set-up.

If the test area is entered after equipment is de-energized, utility workers should place a ground on the high-voltage terminal and any other exposed terminals. High capacity equipment or devices must be discharged through a resistor rated for the available energy. A direct ground must be applied to the exposed terminals when the stored energy drops to a safe level.

Very important: ground the chassis of any test trailer or test vehicle is used in field testing. Provide protection against hazardous touch potentials with respect to the vehicle, instrument panels, and other conductive parts. Control wiring, meter connections, test leads and cables may not be run from a test area unless they are contained in a grounded metallic sheath and terminated in a grounded metallic enclosure, or an equivalent safety system can be installed.

Meters and other instruments must be isolated from test personnel. If this isolation is provided by locating test equipment in metal compartments with viewing windows, interlocks must be provided to interrupt the power supply if the compartment cover is opened. Make the routing and connections of temporary wiring secure against damage, accidental interruptions and other hazards. To the maximum extent possible, keep signal, control, ground, and power cables separate.

If employees will be present in the test area during testing, a test observer must be present. The test observer must be capable of implementing the immediate de-energizing of test circuits for safety purposes.

Conduct routine safety checks of test areas at the beginning of each series of tests. The test operator in charge conducts these routine safety checks before each series of tests and verifies at least the following conditions: (1) barriers and guards are in workable condition and are properly placed to isolate hazardous areas; system test status signals are in operable condition, (2) test power disconnects are clearly marked and readily available in an emergency; (3) ground connections are clearly identifiable, (4) personal protective equipment is provided and used, and signal, ground, and power cables are properly separated.