Final answer:
To determine the length of detonating cord for a blast hole, a rule of thumb is to use a cord length that is 8 diameters side-to-side and 15 diameters deep. Consulting with a qualified engineer or explosives expert is important for accurate calculations.
Step-by-step explanation:
There are a few things to think about when choosing how long detonating cord to use in a blast hole. Using a cord length that is 8 diameters deep and 15 diameters side to side is a common thumb rule. It's crucial to remember that this is only a conservative estimate and could change based on the particulars of the explosion. It is usually advised to seek advice from a licensed engineer or explosives specialist to make sure the right amount of detonating cord is used for a secure and efficient blast.