Day 2: Hardwired Pre-Commissioning

By the end of this module, candidates should be able to use a BMS drawing to physically trace a circuit between the BMS panel and a field device.

Candidates will apply the knowledge gained during Modules 1–6 rather than being re-taught I/O, panel components, relay references or electrical principles.

A BMS drawing shows how a circuit should be installed. The physical installation shows how it has been installed. The candidate's task is to compare the two.

Candidates will be given a BMS point and must use the drawing to locate the corresponding components within the training equipment. Depending on the circuit, this may include:

• BMS I/O
• Relay and relay pole
• Numbered panel terminals
• Field cable
• Field device
• Device supply
• Signal common / reference

Candidates should work systematically rather than tracing random conductors through the equipment.

Candidates are given a digital input circuit such as a Flow Switch or Fan Run Status. They must independently trace the circuit and physically locate:

Candidate question: Does the physical installation match the drawing?

Candidates are given a digital output containing a relay, for example Fan Enable.

This tests whether candidates can correctly apply the relay-reference knowledge learned in Module 5. R5 identifies the relay; R5/1 identifies the required pole/contact. The candidate must locate the correct pole, not simply the correct relay.

Candidate question: Does the physical circuit leave the panel through the relay pole and terminal shown on the drawing?

Candidates are given a 0–10 V pressure sensor circuit. They must use the drawing to identify:

• Sensor supply
• Sensor common / reference
• 0–10 V signal
• Which conductor is the signal?
• What is that signal referenced against?
• Where do both conductors terminate?

Candidates are given the Academy's modulating actuator circuit. They must identify the actuator supply, actuator common and 0–10 V command, then trace:

The objective is not electrical testing. The candidate is proving that they can follow the intended circuit from the drawing to the physical equipment.

Finding the correct device, cable, terminal and I/O does not yet prove that the electrical circuit works correctly. A circuit may appear to terminate in the correct location but still contain:

• An open circuit
• A poor termination
• A short circuit
• Incorrect voltage
• Incorrect polarity
• An incorrect analogue signal
• A reference problem
• A failed field device

Candidates should complete one record for each circuit they trace.

1. Find the point on the drawing.
2. Establish the circuit route.
3. Follow any required drawing references.
4. Locate the corresponding BMS I/O.
5. Locate the relay and correct pole where applicable.
6. Locate the numbered panel terminals.
7. Identify the field cable.
8. Locate the field device.
9. Compare the physical installation against the drawing.
10. Record the result.

This module is about application, not additional theory. Candidates have taken the knowledge gained during Modules 1–6 and used it to follow real BMS circuits.

They should now understand the difference between what the drawing says and what is physically installed. They should also understand that visually tracing a circuit is only the first stage of proving it.

BMS Skills Academy — KNOW IT. PROVE IT. COMMISSION IT.

By the end of this module, candidates should be able to use a multimeter safely and systematically to test typical BMS control circuits and identify whether a fault is located within the panel, field wiring or field device.

The candidate will apply the electrical principles learned in Module 6 to actual BMS circuits and use the circuit-tracing method developed in Module 7.

For every test, candidates should ask three questions:

• What am I measuring?
• What should I expect to measure?
• What will the result prove?

Before testing, candidates must select the correct meter function. Selecting the wrong function can produce an incorrect reading and, particularly when using the current range, can create a fault or damage the meter.

Before relying on a meter reading, candidates should establish that the meter is functioning correctly. A zero reading can mean no voltage, but it can also result from incorrect meter setup, failed leads or poor probe contact.

For voltage testing associated with safe isolation, the appropriate proving procedure from Module 6 applies. During Academy ELV exercises, candidates should still develop the habit of confirming that the meter is operating correctly before trusting the result.

• Measure at the transformer secondary.
• Measure at the panel terminal.
• Measure at the field terminal.
• Measure at the device.
• Introduce an open circuit and identify the last good and first bad measurement.

• Demonstrate correct DC polarity.
• Swap the meter probes and observe +24.0 V versus -24.0 V.
• Relate polarity to electronic sensors and actuators.

Candidates are given an isolated field cable. The drawing identifies a numbered panel terminal and the corresponding field-device connection. The candidate must prove that the conductor actually connects those two locations.

• Safely isolate the circuit.
• Disconnect where required so parallel paths do not affect the test.
• Measure panel end → field end.
• Introduce an open circuit and compare the result.
• Use several cores and ask the candidate to identify the correct conductor.

Introduce two field conductors that should be electrically separate. Candidates first establish from the drawing that continuity is not expected, then test the conductors.

• Investigate whether conductors are cross-connected.
• Check for a short circuit.
• Consider whether another connected component is creating a path.
• Check for incorrect termination.

Use a flow switch, differential pressure switch or simulated plant status contact. Candidates identify COM, NO and NC and prove the contact state before and after operating the device.

Use a panel relay. The candidate uses the drawing to identify the relay coil, relay reference, required pole and COM / NO / NC arrangement. First prove the coil supply, then operate the relay and test the required contact.

• Introduce a fault where the field circuit uses the wrong relay pole/contact.
• Allow the relay to visibly operate while the intended output circuit remains incorrect.

The exact arrangement must always be confirmed against the device and approved drawing.

Use the Academy pressure sensor or signal generator. Candidates identify supply, common/reference and signal, then measure Signal → Correct Common at known values such as 2.5 V, 5.0 V, 7.5 V and 10.0 V. Where the training controller permits, compare the physical signal with the BMS value.

Generate approximately 5.0 V DC at the field device. Measure Field Signal → Field Common, then Panel Signal → Panel Common, then AI → AI Common. The readings should broadly correspond. Introduce a wiring fault and use the change in readings to determine where the signal is lost or altered.

The sensor produces a known signal relative to its own common, but the intended common/reference connection to the BMS input is removed. Candidates prove sensor supply, sensor signal against sensor common and then investigate why the BMS input does not have the intended complete signal/reference circuit.

Use two independently isolated ELV supplies: Supply A on the controller side and Supply B on the field side. The field circuit generates a known analogue signal relative to its own reference.

• TP1 — Signal
• TP2 — Field Common
• TP3 — Controller Common

Candidates measure TP1 → TP2, TP1 → TP3 and TP2 → TP3. The training rig should include a deliberate, controlled and current-limited reference offset so the fault produces a repeatable result rather than relying on unpredictable behaviour between naturally floating supplies.

Fault Condition

The candidate then operates the designed REFERENCE LINK. Once the intended common reference is established, both measurements should be approximately 5.0 V.

The lesson is not to common separate transformer secondaries whenever there is a problem. The lesson is to prove the reference arrangement required by the approved design.

Use the Academy modulating actuator. Command or generate known signals such as 0 V, 2.5 V, 5.0 V, 7.5 V and 10.0 V.

• Measure at the BMS output.
• Measure at the panel terminal.
• Measure at the actuator.
• Observe the physical actuator response.
• Introduce a disconnected field signal and determine whether the fault is panel-side or field-side.

Use a temperature sensor. Disconnect it appropriately from the active input circuit and measure resistance. Compare the result against the manufacturer's temperature/resistance information.

• Is the sensor connected?
• Is it open circuit?
• Is it short circuit?
• Is the measured resistance reasonable for the current temperature?
• Is it the correct sensor type?

The purpose is not to memorise thermistor resistance values. It is to prove whether the sensor and circuit are reasonable against the manufacturer's information.

Use the numbered panel terminal as the practical boundary between panel and field.

For an output, if the correct condition exists at the panel terminal but not at the device, investigate the field side. If it is missing at the panel terminal, investigate the panel side. For an input, work back through the circuit in the opposite direction.

Where a longer circuit contains several accessible test points, test somewhere approximately halfway through the circuit.

• If the expected condition exists there, move towards the device.
• If the expected condition does not exist there, move back towards the source.
• Continue narrowing the search area until the fault is located.

This prevents candidates checking every connection one by one and introduces a repeatable fault-finding technique.

By the end of Day 2, candidates have progressed from reading the drawing and following the circuit to electrically proving the circuit, locating faults, proving rectification and recording the result.

The key fault-finding question is not simply: “Why isn't it working?”

BMS Skills Academy — KNOW IT. PROVE IT. COMMISSION IT.

By the end of this module, candidates should be able to apply a repeatable pre-commissioning method to prove hardwired BMS field points, verify signals and physical responses, diagnose realistic faults and record the outcome without drifting into full functional commissioning.

• Identify the physical field device and associated BMS point from project information.
• Prove the correct device-to-point relationship before assessing accuracy or operation.
• Verify temperature, analogue, digital and actuator signals using appropriate test methods.
• Distinguish command from actual operation and signal scaling from measurement accuracy.
• Diagnose realistic wiring, signal and supply faults using a structured process.
• Restore devices and overrides to their intended condition after testing.
• Record point-to-point status, defects and blockers accurately.

Point-to-point verification must be completed before measurement accuracy or functional verification. A believable BMS value does not prove that the correct physical field device is connected to the correct point.

The purpose of this module is to move from electrical understanding into practical field-device proving. Candidates are expected to use drawings, points schedules, BMS graphics and suitable test instruments together.

Stage 1 — Prove the Point

• Identify the sensor and associated BMS input.
• Open the circuit using the designated sensor test link.
• Confirm the correct BMS point becomes invalid or indicates the expected fault condition.
• Restore the circuit and confirm recovery.

Stage 2 — Verify the Reading

• Use a suitable handheld air-temperature reference probe positioned as close as practicable to the sensing location.
• Allow the readings to stabilise before comparing.
• Investigate discrepancies before applying any offset.
• An infrared thermometer measures surface temperature and is not a valid room-air reference.

Measure the live 0–10 V signal at both ends of the field circuit using the designated signal reference for each measurement.

• Measure transmitter output against the designated transmitter common.
• Measure the corresponding BMS input against the designated input common.
• Compare the readings under the same operating condition.
• Apply a controlled change where appropriate to prove point and signal integrity.
• Convert the measured voltage into the expected engineering value using the issued range.

Scaling Example

Equal voltage readings at the transmitter and input support signal consistency but do not exclude every possible reference or ground-loop problem. A panel simulator proves the panel/input path only; it does not prove the field cable or field transmitter.

• Identify the field contact and associated digital input.
• Operate the relevant contact and confirm that the intended BMS input changes state.
• Confirm the intended NO/NC relationship from the project information.
• Restore the contact and record the result.

• Identify the correct physical actuator and associated BMS output.
• Command representative positions such as 0%, 50% and 100%.
• Observe the actual actuator movement and verify direction.
• Confirm that the correct actuator moves in response to the issued command.
• Restore the point to automatic control after testing.

• Understand the reported fault and expected operation.
• Locate the device, terminals and I/O on the drawings.
• Establish whether point-to-point verification passes.
• Measure the appropriate supply, signal or contact state.
• Compare field measurements against panel measurements.
• Identify, correct or report the fault; restore, retest and document.

The project points schedule is the primary record. Candidates use the actual project-style schedule rather than a separate generic test form.

• Point description and device/equipment reference.
• I/O type, module and channel.
• Point-to-point check status.
• Commissioned by and date.
• Set value and useful comments where applicable.
• Witnessing details where required.

The Equipment Schedule is used alongside the Points Schedule to identify the equipment/device reference and associated I/O.