Technical Trade SchoolBAS-100 foundation-series
BAS-103
Concept reading and source route

BAS-103 Reading Guide

How to use this reading guide

This is the concept-review layer for a 100% online course. Read each module before its lesson, complete the retrieval prompts without looking, then use the linked authoritative sources to verify project-specific editions, requirements, and manufacturer procedures.

Online evidence is not OJL: browser simulations, document cases, and isolated remote equipment build reasoning and documentation skill; supervised field performance is recorded separately.

Module 1

Electrical purpose, charge, voltage, current, resistance and power

Why it matters: Voltage exists between two reference points, current requires a complete path, and low voltage is not automatically low risk.

Vocabulary and working scope

Source/load/path; potential difference; current; resistance; open/closed/short/ground; DC/AC awareness; volts/amps/ohms/watts/VA; polarity/reference; energy.

Source-to-result trace

  1. Locate the controlling requirement and establish authority.
  2. Identify the physical and digital boundaries.
  3. Preserve as-found state and timestamps.
  4. Trace the initiating condition through logic, interfaces, equipment, and process response.
  5. Compare expected and actual evidence.
  6. Calculate with units and stated tolerance.
  7. Record action, result, restoration, uncertainty, and owner.

Worked thinking prompt

A 24 Vac device has voltage at one terminal to ground but no complete return path and will not operate.

Calculation: Apply Ohm law, P=VI, VA relationships, series/parallel basics, and reasonableness with units.

Retrieval prompts

Module 2

Sources, transformers, control power, commons and grounding terms

Why it matters: Similar voltage readings do not make conductors interchangeable; design, source, listing, protection, and reference path govern.

Vocabulary and working scope

Utility/source awareness; transformer primary/secondary; isolation; 24 Vac; Class 2 awareness; VA; fuse/breaker; common; neutral; grounded/grounding/bonding awareness; signal reference; shield.

Source-to-result trace

  1. Locate the controlling requirement and establish authority.
  2. Identify the physical and digital boundaries.
  3. Preserve as-found state and timestamps.
  4. Trace the initiating condition through logic, interfaces, equipment, and process response.
  5. Compare expected and actual evidence.
  6. Calculate with units and stated tolerance.
  7. Record action, result, restoration, uncertainty, and owner.

Worked thinking prompt

Two transformer commons are tied without approved design, causing unstable readings and unexpected current paths.

Calculation: Calculate transformer load/current/spare, voltage drop from supplied data, and parallel-load totals; identify assumptions and limits.

Retrieval prompts

Module 3

AI, AO, BI, BO, universal and enumerated electrical interfaces

Why it matters: The database label AI/AO/BI/BO does not prove the field signal, wiring, reference, or physical process.

Vocabulary and working scope

Dry/wet contact; switched voltage; resistance; 0-10 V; 4-20 mA; pulse; UI/UO; sink/source awareness; common/reference; input impedance/load; state; fail position.

Source-to-result trace

  1. Locate the controlling requirement and establish authority.
  2. Identify the physical and digital boundaries.
  3. Preserve as-found state and timestamps.
  4. Trace the initiating condition through logic, interfaces, equipment, and process response.
  5. Compare expected and actual evidence.
  6. Calculate with units and stated tolerance.
  7. Record action, result, restoration, uncertainty, and owner.

Worked thinking prompt

A 4-20 mA sensor is landed as 0-10 V and displays a plausible but wrong value.

Calculation: Calculate linear scaling, loop current/resistor voltage from supplied values, binary truth, and expected normal/fault readings.

Retrieval prompts

Module 4

Relays, coils, contacts, SPST, SPDT and DPDT

Why it matters: A relay coil and its contacts are isolated functions; normal contact state is defined with the coil de-energized, and ratings/application govern use.

Vocabulary and working scope

Electromagnet/coil; coil voltage/VA; contact common/NO/NC; normal/de-energized state; SPST/SPDT/DPST/DPDT; poles/throws; interposing RIB; isolation; contact ratings; suppression.

Source-to-result trace

  1. Locate the controlling requirement and establish authority.
  2. Identify the physical and digital boundaries.
  3. Preserve as-found state and timestamps.
  4. Trace the initiating condition through logic, interfaces, equipment, and process response.
  5. Compare expected and actual evidence.
  6. Calculate with units and stated tolerance.
  7. Record action, result, restoration, uncertainty, and owner.

Worked thinking prompt

A technician lands a fan-start circuit on NC instead of NO and uses a contact rated for the wrong load type.

Calculation: Build contact truth tables, calculate coil current/VA, compare supplied contact ratings, and reconcile commanded versus actual states.

Retrieval prompts

Module 5

Series, parallel, switches, safeties, permissives and interlocks

Why it matters: Control-circuit logic and safety contacts must be traced in their actual normal/fault states; bypassing is not a training shortcut.

Vocabulary and working scope

Series AND path; parallel OR path; switches; limits; overload contacts; safeties; permissives; interlocks; seal-in awareness; hand-off-auto; fail-safe behavior; proof.

Source-to-result trace

  1. Locate the controlling requirement and establish authority.
  2. Identify the physical and digital boundaries.
  3. Preserve as-found state and timestamps.
  4. Trace the initiating condition through logic, interfaces, equipment, and process response.
  5. Compare expected and actual evidence.
  6. Calculate with units and stated tolerance.
  7. Record action, result, restoration, uncertainty, and owner.

Worked thinking prompt

A fan will not start because one series permissive is open, but the BAS output and relay both operate.

Calculation: Apply Boolean/series-parallel reasoning, voltage-drop expectations across open/closed elements, and transition coverage.

Retrieval prompts

Module 6

Single-phase power and motor control types

Why it matters: Voltage system and motor nameplate/project documentation govern; BAS normally interfaces with the control circuit, not motor conductors.

Vocabulary and working scope

Line/neutral or line/line; 120/208/240 awareness; single-phase motors; capacitors awareness; contactor; overload; disconnect; control transformer; start/stop; proof; packaged equipment.

Source-to-result trace

  1. Locate the controlling requirement and establish authority.
  2. Identify the physical and digital boundaries.
  3. Preserve as-found state and timestamps.
  4. Trace the initiating condition through logic, interfaces, equipment, and process response.
  5. Compare expected and actual evidence.
  6. Calculate with units and stated tolerance.
  7. Record action, result, restoration, uncertainty, and owner.

Worked thinking prompt

A single-phase exhaust fan has control voltage and closed contactor contacts but no motor current because an upstream disconnect is open.

Calculation: Calculate single-phase current/power from supplied values, transformer/control load, expected state readings, and proof timeout.

Retrieval prompts

Module 7

Three-phase systems, starters, contactors and overloads

Why it matters: All motor-power legs are switched and protected as an approved assembly; a BAS relay belongs in the starter control circuit, never inserted into one power leg.

Vocabulary and working scope

Three conductors/phases; line/load; phase-to-phase voltage; rotation awareness; starter; three-pole contactor; overload elements/auxiliary contact; control circuit; disconnect/protection; motor; proof.

Source-to-result trace

  1. Locate the controlling requirement and establish authority.
  2. Identify the physical and digital boundaries.
  3. Preserve as-found state and timestamps.
  4. Trace the initiating condition through logic, interfaces, equipment, and process response.
  5. Compare expected and actual evidence.
  6. Calculate with units and stated tolerance.
  7. Record action, result, restoration, uncertainty, and owner.

Worked thinking prompt

A RIB relay is installed on one leg of a three-phase motor starter, creating a single-phasing and equipment-damage hazard.

Calculation: Calculate balanced three-phase power from supplied V/I/power factor, current imbalance, control-circuit current, and expected auxiliary-contact states.

Retrieval prompts

Module 8

VFD power, control and BAS interfaces

Why it matters: A VFD is power electronics, not merely a relay; BAS control never replaces disconnect, drive safeties, motor protection, or qualified commissioning.

Vocabulary and working scope

VFD line/load; motor leads; start/stop enable; speed reference; HOA/bypass awareness; fault/ready/run; analog/BACnet interface; minimum/maximum; ramp; proof; harmonics/noise; safety.

Source-to-result trace

  1. Locate the controlling requirement and establish authority.
  2. Identify the physical and digital boundaries.
  3. Preserve as-found state and timestamps.
  4. Trace the initiating condition through logic, interfaces, equipment, and process response.
  5. Compare expected and actual evidence.
  6. Calculate with units and stated tolerance.
  7. Record action, result, restoration, uncertainty, and owner.

Worked thinking prompt

The BAS commands 60 percent, the VFD reports run at 36 Hz, but fan proof and duct pressure remain low.

Calculation: Calculate frequency/speed percentage, fan-law awareness from supplied cases, command/feedback error, ramp/proof timing, and load reasonableness.

Retrieval prompts

Module 9

Meters, expected readings and de-energized diagnosis boundaries

Why it matters: A meter does not make a task safe; qualified-person status, risk assessment, correct instrument, verified condition, method, and PPE/program controls govern.

Vocabulary and working scope

Meter functions; leads/ports; category/rating awareness; proving source; voltage/resistance/continuity/current limitations; de-energized condition; expected reading; reference point; uncertainty; visual and document evidence.

Source-to-result trace

  1. Locate the controlling requirement and establish authority.
  2. Identify the physical and digital boundaries.
  3. Preserve as-found state and timestamps.
  4. Trace the initiating condition through logic, interfaces, equipment, and process response.
  5. Compare expected and actual evidence.
  6. Calculate with units and stated tolerance.
  7. Record action, result, restoration, uncertainty, and owner.

Worked thinking prompt

A continuity beep across a coil is treated as proof that the whole control circuit will work under power.

Calculation: Predict readings from the schematic, apply Ohm law, compare measured/supplied tolerance, and state what each result cannot prove.

Retrieval prompts

Module 10

Electrical fault isolation, restoration and professional defense

Why it matters: The learner must stop at the authorization boundary even when the likely answer is known; evidence and safe escalation are part of competence.

Vocabulary and working scope

Complaint; symptom; circuit normal model; source/path/load/reference; open/short/ground/cross/wrong coil/contact/overload/phase/control/mechanical hypotheses; next safe test; escalation; restore.

Source-to-result trace

  1. Locate the controlling requirement and establish authority.
  2. Identify the physical and digital boundaries.
  3. Preserve as-found state and timestamps.
  4. Trace the initiating condition through logic, interfaces, equipment, and process response.
  5. Compare expected and actual evidence.
  6. Calculate with units and stated tolerance.
  7. Record action, result, restoration, uncertainty, and owner.

Worked thinking prompt

A motor is off with BAS command on, relay energized, starter coil de-energized, and overload auxiliary open after reset history.

Calculation: Calculate evidence coverage, voltage distribution from supplied readings, imbalance, timing, and temporary-state/record reconciliation.

Retrieval prompts

Required and deeper reading

Adoption note: Standards, codes, project requirements, owner criteria, manufacturer instructions, and employer safety programs control. Confirm the adopted edition and authority before applying a numeric requirement.