All detonator lead wires shall be electrically insulated. Firing leads or cables of low-energy detonators for explosive assemblies shall be kept properly shorted during setup on the firing point.

5.1.6.7 ELECTRICAL TESTING INSTRUMENTS FOR USE WITH EXPLOSIVES SYSTEMS (EXCEPT THOSE COVERED BY DOE 5610.3)

Testing instruments shall meet certain criteria and be certified and labeled for the types of testing they are permitted to perform.

5.1.6.7.1 CLASSIFICATION

Testing instruments shall be assigned to categories on the basis of electrical characteristics that affect their safe use with explosives systems. Specifically, instrument categories shall be established so that testing instruments in each category can be safely applied to one or more of the following classes of explosives systems:

1. Low-energy or hot-wire initiators (blasting caps, actuators, squibs, etc.)

2. High-energy initiators (exploding bridgewires, slappers, etc.)

3. Noninitiating electrical circuits.

Testing instruments that do not meet the safety criteria may be used on an explosives system only if the activity is considered a remote operation and adequate personnel shielding or separation distance is provided.

5.1.6.7.2 CERTIFICATION

Each DOE facility using electrical testing instruments on explosives systems shall establish a formal system for reviewing and certifying those instruments. Procedures for marking instruments to show their approved use and restrictions on their use shall also be established, so that every testing instrument is prominently labeled with its approved use and with a warning if there is a restriction on its use.

Inspection and calibration of certified instruments shall be required at prescribed intervals or whenever the instrument is opened for servicing or repair.

Records of all certified testing instruments shall be maintained by each DOE facility using electrical instruments to test explosives systems. These records shall include type, manufacturer, model, electrical specifications, wiring diagrams, and failure mode analyses. The Explosives Safety Committee chairperson shall be notified in writing by DOE facilities when they approve new electrical testing instruments for use with initiating systems. The chairperson shall disseminate this information to all committee members.

5.1.6.7.3 ELECTRICAL TESTING INSTRUMENTS FOR USE WITH INITIATING ELECTRICAL CIRCUITS

Instruments used with electrical initiating circuits connected to electroexplosive 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:

1. The output current through a resistance equivalent to that of the minimum resistance initiator of the class shall not exceed 1 1o and shall not exceed 1010 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.

3. 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:

1. 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.

2. 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.

3. 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.