--- name: eol-resistor-calculator description: "Calculates and validates end-of-line (EOL, SEOL, DEOL, TEOL) resistor loops for intrusion alarm panels (Honeywell, DSC, Paradox, Bosch) with wire gauge drop and state tables. Trigger phrases: eol resistor, deol wiring, alarm zone resistor, calculate end of line, double eol tamper." category: architecture risk: safe source: community source_repo: wwewtech/eol-resistor-calculator source_type: community date_added: "2026-09-22" author: wwewtech tags: [security-systems, hardware, electronics, alarm-panel, circuit-design, electrical-engineering] tools: [claude, cursor, gemini, windsurf] license: "MIT" --- # EOL Resistor Calculator: Precision Intrusion Loop Supervision & State Solver Accurately size, configure, and troubleshoot Single (SEOL), Double (DEOL), and Triple (TEOL) end-of-line resistor loops across major security panel architectures with copper wire drop compensation and tamper state discrimination. ## When to Use This Skill Activate this skill when: - Sizing, retrofitting, or diagnosing hardwired security loops on alarm panels (DSC PowerSeries/Neo, Honeywell Ademco Vista, Paradox EVO/Spectra, Bosch B/G Series, Texecom Premier Elite). - The user asks: "How do I wire double EOL on a DSC panel?", "Calculate zone loop resistance for a 200m cable run", "Troubleshoot a constant zone tamper fault", or "What resistor values does Honeywell Vista use?". - Differentiating between Normal, Alarm, Tamper (Short), and Cut (Open) circuit states across varying panel threshold windows. - Sizing copper loop resistance drops on long perimeter runs (e.g. 22 AWG over 150+ meters) to prevent phantom false alarms. Do NOT use this skill when: - Designing wireless sensors or addressable polling loop multiplexers (polling loops use digital transponders, not passive EOL resistors). - Bypassing safety or life-safety supervision circuits (never advise strapping out resistors or bypassing line supervision). - Working on 2-wire smoke detector loops without consulting panel-specific smoke circuit polarity and current-limiting specs. ## Core Mental Models & Non-Negotiable Rules 1. **The Far-End Placement Axiom (Strict Anti-Panel Stacking)**: - Resistors MUST be installed **inside the sensor housing at the farthest physical end of the cable run**. - Placing resistors across screw terminals inside the alarm panel enclosure protects only the metal cabinet itself; the entire 50-meter cable run to the sensor is left vulnerable to undetected wire cuts or staple shorts. - Any wiring diagram showing EOL resistors at the panel board for field sensors is flagged as a Grade 2/Grade 3 compliance violation. 2. **The 4-State Double-EOL (DEOL) Truth Table**: - Double EOL uses two resistors: an End-of-Line resistor ($R_{EOL}$) and an Alarm contact resistor ($R_{ALARM}$). - Standard series-parallel configuration (e.g., DSC standard 5.6k / 5.6k): $$\text{Loop State} = \begin{cases} 0\ \Omega\ (\text{Short Circuit}) & \implies \mathbf{Tamper\ (Short)} \\ R_{EOL}\ (5.6\text{k}\ \Omega) & \implies \mathbf{Normal\ (Secure)} \\ R_{EOL} + R_{ALARM}\ (11.2\text{k}\ \Omega) & \implies \mathbf{Alarm\ (Tripped)} \\ \infty\ \Omega\ (\text{Open Circuit}) & \implies \mathbf{Tamper\ (Cut\ Wire)} \end{cases}$$ - This provides complete supervised discrimination between intruder activation and physical sabotage. 3. **Copper Wire Resistance Compensation Formula**: - Long field cable runs add series loop resistance across both conductors: $$R_{loop} = 2 \times D \times \rho_{gauge}$$ where $D$ is one-way distance in meters, and $\rho_{gauge}$ is resistance per meter: - **22 AWG (0.326 mm²)**: $0.053\ \Omega/\text{meter}$ ($16.14\ \Omega/1000\text{ft}$) - **20 AWG (0.518 mm²)**: $0.033\ \Omega/\text{meter}$ ($10.15\ \Omega/1000\text{ft}$) - **18 AWG (0.823 mm²)**: $0.021\ \Omega/\text{meter}$ ($6.38\ \Omega/1000\text{ft}$) - A 150m run of 22 AWG adds $2 \times 150 \times 0.053 \approx 15.9\ \Omega$. Ensure total loop resistance does not push readings beyond the panel's $\pm 15\%$ ADC tolerance window. 4. **Panel Reference Resistor Standards Matrix**: - **DSC PowerSeries / Neo**: $5.6\text{k}\ \Omega$ SEOL / $5.6\text{k} + 5.6\text{k}$ DEOL. - **Honeywell Ademco Vista**: $2.0\text{k}\ \Omega$ SEOL (Standard zones), $1.0\text{k}$ (Zone 1 on some models). - **Paradox EVO / Spectra**: $1.0\text{k}\ \Omega$ SEOL / $1.0\text{k} + 1.0\text{k}$ DEOL (or ATZ mode with $1.0\text{k} / 2.2\text{k}$). - **Bosch B / G Series**: Dual supervision with $1.0\text{k} / 2.0\text{k}$ or panel-selectable windows. - **Texecom Premier Elite**: $2.2\text{k} / 4.7\text{k}$ or selectable Grade 3 Triple-EOL ($4.7\text{k} / 4.7\text{k} / 2.2\text{k}$ anti-mask). 5. **ADC Voltage Divider Acceptance Windows**: - Security panels measure zone voltage through an internal pull-up resistor ($R_{pullup}$, typically $1\text{k}$ to $3.3\text{k}\ \Omega$) connected to a reference voltage ($V_{ref}$, typically $5.0\text{V}$ or $13.8\text{V}$). - Terminal voltage is given by: $$V_{zone} = V_{ref} \times \frac{R_{loop\_total}}{R_{pullup} + R_{loop\_total}}$$ - Always confirm whether a measured terminal voltage falls inside the manufacturer's specified ADC threshold window before replacing field hardware. ## Named Sins & Anti-Patterns (Что категорически ЗАПРЕЩЕНО) | Anti-Pattern | Manifestation in Code/Workflow | Mandatory Production Counter-Rule | | :--- | :--- | :--- | | **Panel-Terminal Resistor Stacking** | Crimping EOL resistors into the screw terminals on the panel PCB. | Install resistors exclusively inside the remote sensor housing. | | **Vendor Value Cross-Contamination** | Putting 2.0k Honeywell resistors onto a DSC panel requiring 5.6k. | Verify panel model and enforce manufacturer-specific resistance ratings. | | **DEOL Series/Parallel Inversion** | Swapping series and parallel resistors on an alarm PIR contact. | Wire $R_{ALARM}$ in parallel with NC alarm switch; wire $R_{EOL}$ in series with loop. | | **Neglecting Wire Drop on Long Runs** | Ignoring 40+ $\Omega$ wire resistance on a 300-meter warehouse fence zone. | Calculate loop resistance $2 \times D \times \rho$ and verify against panel budget. | | **Twist-and-Tape Resistor Splices** | Twisting resistor leads by hand and wrapping with electrical tape. | Use soldered heat-shrink sleeves or grease-filled B-connectors/crimps. | | **Fire/Burg Supervised Mix-up** | Applying burglar DEOL tamper logic to 2-wire latching fire zones. | Fire loops strictly require Normally Open (NO) contacts with SEOL supervision. | | **Unshielded AC Parallel Run** | Running 22/4 unshielded alarm cable in parallel with 230V mains. | Maintain 300mm physical separation or use twisted shielded pair (STP). | | **Strapping Out Trouble Zones** | Advising a user to twist zone wires together to clear a trouble condition. | Diagnose root cause (open wire, bad contact, corroded resistor) methodically. | | **Confusing NO and NC Contacts** | Treating a magnetic reed switch (NC) like an exit request button (NO). | Verify sensor contact behavior in quiescent, non-alarm states. | | **Unrecorded Commissioning Values** | Leaving an install without recording measured DC resistance values. | Deliver an audit log of measured loop ohms across Normal, Alarm, and Tamper. | ## Concrete Archetypes / Presets ### Archetype 1: Double-EOL (DEOL) Sensor Wiring Schematic (DSC 5.6k) ``` (+) ZONE TERMINAL (Panel) │ ▼ [Core 1: Field Wire] ┌───────┴────────────────────────┐ │ SENSOR HOUSING (Far End) │ │ │ │ TAMPER SWITCH (NC) │ │ ┌────[ / ]────┐ │ │ │ │ │ │ ▼ ▼ │ │ ( ) ( ) │ │ │ │ │ │ │ ALARM RELAY (NC) │ │ │ ┌────[ / ]────┐ │ │ │ │ │ │ │ │ │ R_ALARM │ │ │ │ └───[5.6k]────┘ │ │ │ │ │ │ ▼ ▼ │ │ R_EOL [5.6k] │ │ │ │ │ │ └─────┼─────────────┼────────────┘ │ │ └─────────────┘ ▲ │ [Core 2: Field Wire] (─) COMMON TERMINAL (Panel) State Resistance: • Secure: 5.6k Ω • Alarm: 11.2k Ω (Alarm contact opens, forcing current through R_ALARM) • Tamper: 0 Ω (Short circuit) or ∞ Ω (Cut wire or Tamper contact opens) ``` ### Archetype 2: Loop Resistance & Tolerance Calculator (Python 3.10+) ```python def calculate_loop_parameters( panel_eol_nominal: float, panel_tolerance_pct: float, one_way_distance_m: float, wire_gauge_awg: int = 22, deol_mode: bool = True ) -> dict: # Ohms per meter for solid annealed copper conductors RESISTANCE_PER_M = {18: 0.0209, 20: 0.0333, 22: 0.0530, 24: 0.0842} rho = RESISTANCE_PER_M.get(wire_gauge_awg, 0.0530) wire_loop_ohms = 2.0 * one_way_distance_m * rho normal_resistance = panel_eol_nominal + wire_loop_ohms alarm_resistance = (panel_eol_nominal * 2.0 if deol_mode else float('inf')) + wire_loop_ohms tol_window = panel_eol_nominal * (panel_tolerance_pct / 100.0) normal_min = panel_eol_nominal - tol_window normal_max = panel_eol_nominal + tol_window is_normal_acceptable = (normal_min <= normal_resistance <= normal_max) return { "wire_loop_resistance_ohms": round(wire_loop_ohms, 2), "measured_normal_expected": round(normal_resistance, 2), "measured_alarm_expected": round(alarm_resistance, 2), "panel_acceptance_window": (round(normal_min, 2), round(normal_max, 2)), "is_acceptable": is_normal_acceptable, "recommendation": "OK" if is_normal_acceptable else "Wire resistance exceeds panel tolerance! Upsize to 20 AWG or 18 AWG." } ``` ### Archetype 3: Multimeter Field Diagnostic Workflow ```markdown 1. Disconnect zone loop wires from panel terminal Z1 and COM. 2. Set digital multimeter to 20k Ω DC resistance range. 3. Clip probes to black and red loop wires. 4. Read resistance: - Reading = 0 Ω: Direct short on cable or tamper circuit pinched. - Reading = ~5.6k Ω: Loop is secure and healthy. - Reading = ~11.2k Ω: Sensor is currently tripped (door open, motion active). - Reading = O.L (∞ Ω): Broken conductor, disconnected terminal, or open tamper switch. 5. Reconnect to panel and verify terminal voltage across Z1 and COM: - Normal secure: 2.2V - 2.8V DC (on 5V pullup). - Alarm: 3.5V - 4.1V DC. - Tamper/Short: 0.0V DC. - Cut/Open: 5.0V DC. ``` ## The Pre-Emit Quality Gate Checklist Before emitting any alarm wiring advice, schematic, or resistor calculation: - [ ] **Placement Verification**: Explicitly mandate resistor placement at the remote detector, strictly barring panel-terminal stacking. - [ ] **Manufacturer Compliance**: Verified nominal EOL values match the specific panel model (Honeywell 2.0k, DSC 5.6k, Paradox 1.0k, etc.). - [ ] **Wire Gauge Compensation**: Calculated two-conductor wire loop resistance for distances $> 50$ meters. - [ ] **DEOL State Coverage**: Documented all 4 states (Normal, Alarm, Tamper Short, Tamper Open). - [ ] **Fire Circuit Distinction**: Confirmed burglary DEOL logic is never recommended for latching fire loops. - [ ] **Physical Connection Standards**: Specified soldered heat-shrink or B-connector crimps over raw tape twists. - [ ] **Zero Supervision Bypass**: Zero instructions provided to defeat or bypass loop supervision resistors. ## Self-Correction & Verification Loop ### Bad (Vibe-Coded AI Slop Output): > "To wire an alarm sensor, just twist the resistor onto the zone screw terminals on the panel board. A 1k resistor usually works for all panels. If you get a zone fault, just bypass the zone or short the wires together." *Problems: Fatal panel-terminal stacking, generic wrong resistor value, advises bypassing safety supervision, ignores tamper discrimination.* ### Good (Production EOL Resistor Calculator Output): > For a **DSC PowerSeries Neo** panel using a **Double-EOL (DEOL)** PIR detector over an **80m run of 22 AWG** cable: > 1. **Resistor Placement**: Install two 5.6k $\Omega$ resistors (5% tolerance, 0.25W) strictly inside the PIR housing at the far end of the run. > 2. **Wiring Topology**: > - Connect Tamper switch in series with the loop. > - Connect first 5.6k $\Omega$ resistor ($R_{EOL}$) in series with the loop. > - Connect second 5.6k $\Omega$ resistor ($R_{ALARM}$) in parallel across the NC Alarm relay contacts. > 3. **Wire Resistance Drop**: 80m of 22 AWG adds $2 \times 80 \times 0.053 = 8.48\ \Omega$. Total secure loop resistance will be $5,608.5\ \Omega$, well within DSC's $\pm 10\%$ acceptance window ($5,040\ \Omega$ to $6,160\ \Omega$). > 4. **Multimeter Diagnostic Verification**: > - Secure: $5.61\text{k}\ \Omega$. > - Walk-test (Alarm): $11.21\text{k}\ \Omega$. > - Sensor cover removed (Tamper): $\infty\ \Omega$ (Open). > - Crushed wire (Short): $8.5\ \Omega$ (Panel registers Tamper Short). ## Limitations - EOL values, wiring topologies, and zone states are panel- and detector-specific. Use the installation manual and approved wiring diagram for the exact model; the examples are not universal specifications. - Work on alarm systems only with owner authorization and qualified personnel. Do not bypass supervision, disable an active alarm, or leave a protected site without a verified restored state. - Cable resistance and resistor tolerances are estimates. Measure the installed loop and confirm the panel's published acceptance ranges before changing configuration.