Electrical Testing Instruments for Use With Initiating Electrical Circuits

DOE-HDBK-1092-2004

5.1.6.7.3

ELECTRICAL TESTING INSTRUMENTS FOR USE WITH INITIATING

ELECTRICAL CIRCUITS

Instruments used with electrical initiating circuits connected to electro-explosive devices may be

further categorized for use with either low-energy initiators or high-energy initiators. All testing

instruments used for this purpose shall be current-limited. Before being used on initiating

circuits, every instrument wiring diagram and internal circuitry design shall be analyzed,

examined, and certified for the following:

The output current through a resistance equivalent to that of the minimum resistance

initiator of the class shall not exceed 1 percent and shall not exceed 10 percent of the no-

fire rating for the most sensitive initiator of the class. The current-limiting features of the

testing instrument shall be internal to the instrument and shall not depend on the circuit load

characteristics.

2. The internal circuitry shall ensure isolation features that require, at a minimum, two

independent failure modes before the specified output current can be exceeded.

A comprehensive (point-to-point, if possible) wiring check shall be made to ensure that the

wiring corresponds to the diagram and that all components are functioning properly and

within specifications.

5.1.6.7.4

ELECTRICAL TESTING INSTRUMENTS FOR USE WITH NONINITIATING

ELECTRICAL CIRCUITS

Testing instruments in this category are used with electric circuits connected to instruments

such as strain gauges, pin switches, pressure transducers, thermocouples, and electrical

components that are affixed to or within an assembly with explosives. These instruments shall

meet the following requirements:

Each use of the testing instrument shall be analyzed to ensure that there is no credible

scenario where the normal test energy from the testing instrument can ignite explosive

charges or initiators in the test. This testing shall be consistent with Section 5.1.6.7.3.

Where a testing instrument is used to make measurements on sensors directly applied to

explosives (e.g., bonded strain gauges or pin switches), the testing instrument shall be

certified and controlled.

Testing instruments shall be prominently marked with restrictions on their use. Many of

these testing instruments do not meet the requirements for use with initiating systems and

shall be marked to prevent their use on this type of circuit.

5.2

PREVENTION OF EXTERNAL IGNITION AND EXPLOSION

Explosives are hazardous by themselves, but around electricity they become even more

dangerous: an arc, spark, or hot surface can easily touch off an explosion. Therefore, the

electrical installation shall contain these ignition sources or house them in an area well

separated from the explosives storage area.

The electrical installation shall prevent accidental ignition of flammable liquids, vapors, and

dusts in the atmosphere. In addition, because portable electrical equipment is often used

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