Which of the following triggers millisecond delay connectors for det cord?

• A. They require manual triggering
• B. They are activated by a detonator switch
• C. They are affected by weather conditions
• D. A falling rock

Answer: (D)

Millisecond delay connectors work by introducing a tiny, precise delay inside the connector after the first segment has been ignited. The trigger is the detonation arriving from the initiator at the start of the det cord—once the blasting cap or detonator fires, the detonation wave enters the delay element, waits for a few milliseconds, and then continues to the next segment. They are not manually triggered, and they are not reliably triggered by weather conditions or by a falling rock. The whole timing sequence relies on the initial detonator, with the connector providing the controlled delay between segments.