Systems Underload

DOE-HDBK-1092-98

2.13.4.6 SYSTEMS UNDER LOAD

Electrical equipment intended to switch current shall have a rating sufficient for the current. Manual

switches and disconnects, taps, terminators, and nonenclosed switches shall not be operated while

under load, unless the devices are rated as load-break type and are so marked.

2.13.4.7 WORKING WITH TEST INSTRUMENTS AND EQUIPMENT

Sometimes it becomes necessary to check the continuity of power circuits, control circuits, etc., by

using a particular testing instrument designed for the testing involved. The voltage device used shall

be rated for the application. Proximity testers and solenoid-type devices should not be used to test

for the absence of AC voltage because they have a lower voltage (usually in the range of 50 to 110

volts) below which they will not detect voltage, even if it is present. Also, these testers will not detect

DC voltage or detect AC voltage in a cable that is shielded. They are very useful in certain

applications such as finding cables that go through a panel but do not terminate in the panel. However,

it should be noted that just because a proximity tester does not detect voltage does not mean that the

equipment or device is actually deenergized. The absence of voltage can only be verified with a

voltmeter rated for the application.

Voltmeters, both analog and digital, are designed for a number of applications from appliance

troubleshooting to power system testing. The type of voltmeter used depends on where in the power

system you are using the meter. The user must read and understand the manufacturers' instructions

on the use and application of the voltmeter. When a multi-function, multi-scale meter is used, it is

important for the user to select the function and scale necessary for the task being performed in order

to avoid damage or destruction of the meter and injury to the employee. See ANSI/ISA S82.01,

S82.02, S83.03, International Electrotechnical Commission (IEC) 1010-1, and UL 1244 for more

information on the application and ratings of voltmeters.

The following should apply when working with test instruments and equipment on energized

circuits.

2.13.4.7.1 QUALIFIED EMPLOYEES

Only qualified workers who are knowledgeable and have been trained to work safely with test

instruments and equipment on energized circuits shall be permitted to perform testing work on

electrical circuits or equipment where there is danger of injury from accidental contact with

energized parts or improper use of the test instruments and equipment.

2.13.4.7.2 VISUAL INSPECTIONS

Test instruments and equipment and all associated test leads, cables, power cords, probes, and

connectors shall be visually inspected for external defects or damage before being used on any shift.

If there are defects or evidence of damage that might expose an employee to injury, the defective or

damaged item shall not be used until required repairs and tests have been made.

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