Electric Detonator (Blasting Cap)
Definition
A metal-shell initiating device containing a bridgewire assembly, primary explosive (lead azide), and output charge (PETN or RDX). Firing current through the bridgewire heats the primary explosive, initiating the output charge and producing a detonation wave at the base of the shell.
- Housing
- Metal shell
- Primary explosive
- Lead azide
- Output charge
- PETN or RDX
- Initiation
- Bridgewire heated by firing current
Common questions
What is the forensic significance of the bridgewire assembly after a blast?+
Fragments of the bridgewire, shell, and leg wires often survive an explosion and can be recovered at the scene; their design and manufacturing marks can help identify the detonator type and sometimes the manufacturer or batch, supporting device reconstruction.
Why does the two-stage design (primary then output charge) matter for hazard assessment?+
The small, sensitive primary charge amplifies a low-energy electrical signal into a full detonation wave able to reliably initiate a much less sensitive output charge, which is why detonators are treated and regulated separately from bulk explosives despite their small size.
Related terms
- ATF Explosives Industry Programs Branch (EIPB)
- The US federal unit within the Bureau of Alcohol, Tobacco, Firearms and Explosives responsible for licensing, compliance inspection, and database management for...
- Bridgewire
- The high-resistance wire element within an electric detonator, typically nichrome or platinum-iridium, that converts firing current into heat to ignite the pyrotechnic...
- Deflagration-to-Detonation Transition (DDT)
- The acceleration of a deflagrating burn front to supersonic detonation velocity, triggered by confinement. Relevant to understanding how improvised devices using low...
- Detonating Cord
- A cord with a PETN explosive core (5-40 g/m) that detonates at approximately 6,400 m/s when initiated. Used to connect multiple charges...
- ENFSI Monopoly Programme
- The European Network of Forensic Science Institutes working group on explosives and gunshot residue analysis, which coordinates inter-laboratory method harmonisation and cross-border...
- Nonel Shock-Tube System
- A non-electric initiating system using a hollow plastic tube coated internally with approximately 18 mg/m of HMX. A low-energy shock propagates through...
- PESO (Petroleum and Explosives Safety Organisation)
- The Indian regulatory authority under the Ministry of Commerce and Industry that administers the Explosive Substances Act 1908 and subordinate rules, including...
- Safety Fuse
- A black powder-cored initiating cord burning at approximately 8-10 mm/s. Used for controlled delay ignition; forensic signature is black powder residue at...
- Unique Identifier (UI)
- A mandatory traceable code on each commercial detonator sold in the UK and EU post-2013, required by the Explosives for Civil Use...