The code **16-4 FPLP** refers to a specific type of fire alarm cable used in building construction and security systems. It is defined by its gauge, conductor count, and safety rating. --- ### 1. Breakdown of the Specification | Component | Meaning | Description | | :--- | :--- | :--- | | **16** | American Wire Gauge (AWG) | The thickness of the wire. 16 AWG is relatively thick, allowing for longer distances and higher current capacity compared to 18 or 22 AWG. | | **4** | Conductor Count | There are **4 insulated wires** inside the main outer jacket. | | **FPLP** | Fire Power Limited Plenum | This is the NEC (National Electrical Code) rating for fire safety. | --- ### 2. The FPLP Rating Details The "FPLP" designation is the most critical part for electronic installations: * **FP (Fire Protective):** Designed specifically for fire alarm systems. * **PL (Power Limited):** Rated for circuits where the power is limited to prevent fire hazards if a short circuit occurs. * **P (Plenum):** This indicates the cable is rated for installation in **plenum spaces** (the areas in buildings used for air circulation, like above drop ceilings or under raised floors). * Plenum-rated cables use special insulation (often low-smoke PVC or Teflon) that emits very little smoke and no toxic fumes if they catch fire. --- ### 3. Technical Characteristics * **Shielding:** Usually comes in two versions: **Unshielded** (for general use) or **Shielded (FPLP-R)** with an aluminum foil wrap to prevent electromagnetic interference (EMI). * **Voltage Rating:** Typically rated for **300 Volts**. * **Color Coding:** The 4 conductors are standardly colored **Black, Red, White, and Blue** (or sometimes Green) to help technicians identify circuits. * **Temperature Range:** Generally rated for **-20°C to +75°C**. --- ### 4. Common Applications This cable is used in electronic systems where high reliability and fire safety are required: 1. **Fire Alarm Systems:** Connecting smoke detectors, pull stations, and notification appliances (horns/strobes). 2. **Voice Evacuation:** Used for emergency speaker systems in large buildings. 3. **Microprocessor Controlled Systems:** The 4 conductors allow for both power (2 wires) and data/signal communication (2 wires). ---