Eol Resistor Calculator

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)