eol-resistor-calculator – Other skill for AI agents

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.
• Use the exact listed installation and grading rules; this guide cannot certify Grade2/Grade3 compliance.

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{Fault\ (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}$$

• These electrical states aid supervision; they do not prove the cause or rule out 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 documented resistance windows, allowing for resistor/cable/temperature tolerances.

4. Model-specific reference values:

• The cited PowerSeries Neo manual shows5600Ω secure,11200Ω violated,0Ω fault and open-circuit tamper for its DEOL configuration.
• Do not generalize values across Honeywell, Paradox, Bosch, Texecom or even different zones/configurations of the same model. Obtain the exact installation manual and zone programming first.

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 | Using another panel’s resistor value without checking the exact zone manual. | 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. | Use the exact listed fire-zone wiring and detector manual; burglary DEOL logic is not a generic fire-loop design. |

| Unshielded AC Parallel Run | Running 22/4 unshielded alarm cable in parallel with 230V mains. | Follow local separation/wiring rules and the panel manual; shielding does not make unsafe proximity to mains acceptable. |

| 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 -- [NC tamper] -- [R_EOL 5.6k] --+-- [NC alarm] --+-- COM
                                        |                |
                                        +-- [R_ALARM] ---+
                                            5.6k
All resistors and contacts above are at the approved remote detector end.

State Resistance:
• Secure:  5.6k Ω
• Alarm:  11.2k Ω (Alarm contact opens, forcing current through R_ALARM)
• Fault: near0 Ω (short circuit, plus cable resistance to the fault)
• Tamper: ∞ Ω (cut wire or tamper contact opens)

Archetype 2: Loop Resistance & Tolerance Calculator (Python 3.10+)

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}
    import math
    if not all(math.isfinite(v) for v in (panel_eol_nominal, panel_tolerance_pct, one_way_distance_m)):
        raise ValueError("Finite inputs required")
    if panel_eol_nominal <= 0 or not 0 <= panel_tolerance_pct < 100 or one_way_distance_m < 0:
        raise ValueError("Invalid resistance, tolerance or distance")
    if wire_gauge_awg not in RESISTANCE_PER_M:
        raise ValueError("Unsupported wire gauge; supply measured manufacturer data")
    rho = RESISTANCE_PER_M[wire_gauge_awg]
    
    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)),
        "normal_within_assumed_window": is_normal_acceptable,
        "recommendation": "OK" if is_normal_acceptable else "Wire resistance

… (full content is in the download package)