Standards, Codes & Basic Electronics

Several bodies create the rules that govern alarm installation. Understanding who does what is a guaranteed exam topic.

The Key Organizations

• ANSI (American National Standards Institute) — writes the guides used to develop standards and codes.
• UL (Underwriters Laboratories) — tests and lists equipment; judges installations against set standards.
• UL also lists companies for specific types of installations, in addition to testing/listing equipment and judging installations against set standards.
• NFPA (National Fire Protection Association) — publishes the national fire and electrical standards (NEC, NFPA 72, 101, 170).
• FM (Factory Mutual) — also tests equipment but less widely used than NFPA/UL; does not always agree with NFPA.
• AHJ (Authority Having Jurisdiction) — interprets rules, enforces the code, approves equipment in your local area.
• MRLS — municipalities have the right to enact a "More Restrictive Local Standard" stricter than the state standard.
• Code changes happen through committee/board review, or by petition from individuals, industry groups (lobbying), or outside parties.
• In NY, the DOS Division of Code Enforcement and Administration trains Code Enforcement Officials (CEOs) and maintains the Energy Conservation Construction Code; codes are reviewed on a 3-year ICC cycle (e.g., the 2010 CO-detector requirement).
• RCNYS: in this "home rule" state, the Residential Code of NYS is an alternate compliance path for residential electrical work.
• Codes state minimums — a local code cannot override a higher authority (Federal > State > County > Town > AHJ).

NFPA Documents You Must Memorize

The National Electrical Code (NEC / NFPA 70) governs all electrical and low-voltage wiring in the United States. First published in 1897, updated every three years, adopted in all 50 states. Know these eight articles in this exact order.

Article 90 — Purpose of the NEC

Article 90 defines WHY the NEC exists and establishes the authority framework. It is tested on almost every exam.

• Purpose (90-1): The NEC exists for the practical safeguarding of persons and property from hazards arising from the use of electricity.
• Adequacy: Contains provisions considered necessary for safety — compliance does NOT guarantee an efficient, convenient, or adequate installation.
• NOT a design spec: The Code is NOT intended as a design specification and NOT an instruction manual for untrained persons.
• Enforcement (90-4): Intended for mandatory application by governmental bodies. The AHJ has authority for interpretations, approvals, and granting special permissions.
• Formal Interpretations (90-5): Formal Interpretation Procedures promote uniformity in applying the NEC.

Article 110 — Requirements for Electrical Installations

Article 110 establishes how electrical work must be executed — quality, approval, and workmanship standards.

• 110-12 Mechanical Execution: All electrical equipment SHALL be installed in a neat and workmanlike manner.
• Unused openings: All unused openings in boxes, cabinets, and enclosures must be closed (prevents spread of fire or gases).
• Equipment approval: Equipment shall be acceptable only if listed, labeled, or otherwise found acceptable to the AHJ.
• Working clearances: Adequate space must be maintained around electrical equipment for safety and serviceability.

Article 250 — Grounding & Bonding

Article 250 covers grounding and bonding of all electrical systems. For alarm installers, this is one of the most heavily tested articles.

• Wire type: Grounding wire must be solid copper (NOT stranded, NOT aluminum). All alarm system panels require copper only.
• Wire size: One AWG size smaller (thicker wire) than the largest wire in the panel.
• 14 AWG — panel supplied from 120 VAC with 15-amp overcurrent protection.
• 12 AWG — panel supplied from 120 VAC with 20-amp overcurrent protection.
• Routing: Run the wire DOWN, with large radius curves, the shortest distance possible.
• Priority 1 — Cold water pipe: Connect to the street side of the water meter (use your own clamp).
• Priority 2 — Ground rod: If water pipe is unavailable or plastic.
• Bonding: All grounds must be BONDED together — minimum 6 AWG bonding wire.

Article 300 — Wiring Methods

Article 300 covers how and where conductors are installed, protected, and supported. These physical installation rules apply to all wiring regardless of voltage.

• Physical protection: All wiring must be protected from physical damage.
• Protection within 7 feet of the floor: Cable in areas where it could be damaged must be protected — in conduit, raceway, or otherwise guarded.
• Fastening: Alarm/low-voltage cable must be fastened and supported at least every 18 inches.
• Fittings: All wiring entering boxes or enclosures must pass through approved fittings.
• Wet locations: Boxes and cable in indoor wet locations must have a minimum 1/4-inch airspace between the enclosure and the wall.
• Elevator shafts: Wiring in elevator shafts must directly relate to the elevator — no other circuits allowed.
• Wire markings: NEC rating, UL listing, and NY State Toxicity Requirements must appear on the cable jacket.
• Ducts/plenums (300-22): no wiring in ducts carrying dust or flammable vapor; only Type MI, MC, EMT, IMC, or RMC permitted in air-handling spaces.
• Flexible metal tubing for plenum wiring is also called "Greenfield" or "BX."

Article 500 — Hazardous (Classified) Locations

Article 500 covers wiring in locations where fire or explosion hazards exist. Know the three classes and use approved equipment in these environments.

• Scope (500-1): Covers all voltages where fire/explosion hazards may exist.
• Class I (501-4): Class I hazardous locations (flammable gases/vapors) require explosion-proof equipment and wiring methods per NEC Article 501, Section 501-4.
• Class II (500-14): Switches, relays, and current-breaking contacts for bells, horns, and sirens must have enclosures approved for Class II locations.
• Class III: Alarm systems in Class III locations comply with Article 503 for wiring methods.
• Cable required in hazardous locations: Use PLTC (Power Limited Tray Cable) — standard CL2/CL3 is not acceptable.

Article 725 — Remote Control, Signaling & Power-Limited Circuits

Article 725 defines the three circuit classes governing most alarm system wiring. This is one of the most exam-heavy articles for alarm installers.

• Safety Control (725-4): Remote-control circuits to safety control equipment shall be classified as Class 1 if failure introduces a direct fire or life hazard.
• Class 1 vs. Communications (725-5): Class 1 circuits SHALL NOT be run in the same cable as communications circuits.
• Physical protection (725-18): Where damage to a safety-control Class 1 circuit would create a hazard, conductors must be in conduit, IMC, EMT, Type MI, or Type MC cable.
• Aerial extension (725-19): Class 1 circuits extending aerially beyond one building must also comply with Article 225.
• Over-current protection (725-35): OCDs shall NOT be interchangeable with devices of higher ratings.
• Transformer circuits (725-37): Transformers supplied from light/power circuits must be protected by an OCD rated NOT over 20 amperes.
• Separation (725-38): Class 2 and 3 open conductors must be separated at least 2 inches from Class 1, power, or light conductors.
• Grounding (725-43): Class 2 and 3 circuits must be grounded per Article 250.
• Overcurrent/wiring method (725-12/14): conductors 14 AWG and larger are protected per Article 300; Class 1 wiring method also follows Article 300.
• Smaller conductors (725-15/16): 18/16 AWG permitted for Class 1 circuits within Article 400 ampacity limits, with 600V-rated insulation.
• Class 1 grounding (725-20): Class 1 circuits and equipment must also be grounded per Article 250.
• Power limiting (725-31/32): Class 2/3 power is inherently limited, or limited via source + overcurrent device; power supplies are not paralleled unless listed for that use.
• Marking (725-34): Class 2/3 power supply units must be durably marked, in a visible spot, with their class and electrical rating.
• Co-location: Class 2/3 conductors may share a cable/raceway with jacketed Article 760 or 770 cables.
• Extension beyond one building (725-42): Class 2/3 conductors near conductors over 300V-to-ground must also meet Article 800.
• Class 1 Remote-Control/Signaling (non-power-limited): a separate variant of Class 1, permitted up to 600V with a source that is NOT required to be power-limited — distinct from Class 1 Power-Limited (Class 1 PL), which is capped at 30V/1000VA.

Article 760 — Fire Protection Signaling Circuits

Article 760 specifically governs fire alarm system wiring — from the fire alarm control panel to all connected devices. Covered in full in Module 4.

• NPLFA (Non-Power-Limited Fire Alarm) circuits — require conduit or equivalent protection like Class 1 circuits.
• PLFA (Power-Limited Fire Alarm) circuits — may be run with less stringent protection (like Class 2/3).
• Cable designations: FPL (general purpose), FPLP (plenum), FPLR (riser), FPLS (shielded).
• Circuit integrity: Fire alarm cables must maintain electrical integrity during a fire — survivability is required.
• Fire circuits must be identified as such at the control panel and at every junction, and cannot share a cable/raceway/conduit with high-voltage circuits.

Article 800 — Communications Circuits

Article 800 governs telephone, data, and broadband communications wiring. Alarm systems often use communications infrastructure — covered in depth in Modules 2 and 5.

• Scope: Covers wiring from telephone company terminals to the customer premises equipment.
• Cable types: CM (general), CMR (riser), CMP (plenum), CMX (dwelling only).
• Entrance protection: Communications conductors entering from outside must be protected against lightning and power surges.
• Class 2/3 in same cable: If Class 2/3 circuits share a cable with communications wiring, those circuits become subject to Article 800.

The Atom & Electron Flow

All electricity is based on the movement of electrons. Energy applied to a material causes electrons to move from one atom to the next in a chain reaction — this is electric current.

• Conductors (copper, gold, silver) — loosely held outer electrons; current flows freely.
• Insulators (glass, rubber, vinyl, PVC) — tightly held electrons; current cannot flow.
• Electrons move from negative to positive (conventional current shown flowing + to −).
• Like charges repel; unlike charges attract.

Closed vs. Open Circuits

• Closed circuit: current flows — resistance is finite; a complete, unbroken path exists.
• Open circuit: resistance is infinite (∞) — flow stops completely. Any break in the path creates an open.

The Four Electrical Quantities

Ohm's Law (George Simon Ohm, 1826)

Raise the voltage → current goes up. Raise the resistance → current goes down.

AWG Wire Resistance Table

Batteries — Series vs. Parallel

Electric Current & the Human Body