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Switchboard Condition Monitoring for Existing Boards
A switchboard can look normal during a scheduled inspection and still be developing a fault between visits. A loose termination, overloaded connection, ageing insulation, nuisance leakage path or changing load profile may not announce itself until damage has already started.
That is where condition monitoring earns its place. It does not replace mandatory protection, inspection or testing. It gives maintenance teams another stream of evidence, especially where faults develop slowly and intermittently.
For existing boards, the practical question is not “Can we monitor everything?” It is “Which changes would give useful warning, where should we measure them, and who will respond when the system raises a concern?”
Condition monitoring supports maintenance, not protection
Switchboard condition monitoring should sit beside the normal protection scheme. Circuit breakers, fuses, residual current devices and other protective devices still perform their required safety functions. Monitoring adds visibility into developing conditions that may not yet trip protection.
Two useful signals for many existing boards are temperature and residual current.
Temperature monitoring can help identify changes around selected joints, terminations and conductors. A rising temperature may point to a poor connection, a load change, imbalance, ventilation issue or another factor that needs inspection.
Residual current monitoring can help track leakage current trends on selected feeders. That may be useful where equipment uses filters, variable speed drives, power supplies or other electronic loads that can affect leakage behaviour over time.
The value is not only in the measurement. The system must show where the change occurred and make sure someone reviews it. Without that, condition monitoring becomes another list of unattended notifications.
Start with the board and its maintenance history
Existing switchboards come with history. Some have clear drawings and recent test records. Others have undocumented changes, spare ways used over time, mixed equipment ages and uneven labelling.
Start by reviewing the board before choosing any sensors.
Useful inputs include:
The single-line diagram
Recent inspection and thermography findings
Known problem circuits or nuisance trips
Load records, if available
Details of connected equipment
Board construction, ventilation and access
Previous repair or modification notes
This review helps set the monitoring scope. A board with a history of warm cable terminations may suit targeted temperature monitoring. A board feeding electronic loads may benefit from residual current trend monitoring on selected feeders.
The Acrel range includes electrical monitoring and sensing options that can support this type of assessment. The right choice still depends on the board, the risk, the installation constraints and the maintenance response.
Avoid the trap of measuring everything because sensors are available. More channels do not always mean better maintenance. A smaller set of well-selected points, with a clear response plan, is often more useful than broad coverage that no one reviews.
Choose monitoring points that match likely failure modes
Condition monitoring works best when each measurement has a reason. The question to ask is simple: if this value changes, what action would it trigger?
Temperature monitoring around selected connections
Heat is often a sign that something has changed. In a switchboard, useful temperature monitoring locations may include:
Main incoming connections
Busbar joints, where suitable and accessible
Outgoing feeder terminations
High-load circuits
Connections with previous inspection concerns
Areas affected by poor ventilation or dust build-up
A high temperature reading should not automatically be treated as proof of a loose connection. Load matters. Ambient temperature matters. So does the behaviour of similar circuits.
A connection running warmer than expected may be carrying more current than before. It may sit in a hotter part of the enclosure. It may also be behaving differently from comparable connections under similar load. The reading becomes useful when maintenance teams compare it with context.
Where possible, pair temperature data with load data. This helps avoid false assumptions. A warm termination at high load may call for review. A termination that becomes warmer than similar phases under similar load may deserve closer attention.
Residual current monitoring on selected feeders
Residual current measurements need the same care. Many normal loads create some leakage current, especially electronic equipment with filters, drives and switch-mode power supplies.
A residual current monitor can help identify changes over time, but it must suit the expected waveform and application. Different loads can produce different leakage characteristics. The device selection should match what the circuit is likely to carry.
Before setting alarms, establish normal behaviour. That may include:
Typical readings during normal operation
Readings during start-up and shutdown
Variations across shifts or production cycles
Effects of weather, moisture or cleaning
Changes when major equipment is switched on or off
Residual current monitoring can support maintenance decisions, but it is not a substitute for required residual current protection. Protection devices must still be selected, installed and tested for their required purpose.
Monitoring signal | What it may show | What to check before acting |
Connection temperature | Load change, poor termination, imbalance, ventilation issue | Load, ambient temperature, phase comparison and inspection history |
Residual current | Leakage trend, equipment change, insulation concern, filter behaviour | Normal operating pattern, waveform type, connected equipment and protection settings |
Communication status | Sensor or gateway issue | Power supply, signal path, enclosure effects and device health |
Design the installation for the existing board
Retrofitting monitoring into a switchboard is still electrical work. Wireless sensing may reduce control wiring, but it does not remove the need for safe design, installation and verification.
The design needs to consider:
Electrical clearances
Insulation and creepage requirements
Mechanical fixing
Heat and vibration
Access for maintenance
Enclosure ratings
Cable routing
Segregation from power circuits
Effects on existing certification or compliance
Communication through the enclosure
Metal switchboard enclosures can affect wireless communication. A sensor may work during bench testing and behave differently once fitted inside a live board with closed doors. The design should allow for signal testing in the final installed position.
Sensor access also matters. If batteries, clips or modules need future attention, maintenance staff must be able to reach them safely. A monitoring system that creates difficult future access may reduce risk in one area while adding it in another.
All work should follow the applicable Australian standards, site rules and manufacturer instructions. A licensed electrical worker should assess and carry out work where required. This article is general information, not a substitute for project-specific electrical design.
Set alarms around a meaningful response
An alarm is only useful if it leads to a defined action. If it only adds noise, people learn to ignore it.
For temperature monitoring, alarms should account for the way the board operates. A fixed limit may be suitable in some cases, but it may miss useful context. In other cases, trend-based alarms, comparison between phases, or alarms tied to load conditions may give better evidence.
For residual current monitoring, avoid setting thresholds before normal behaviour is understood. Many circuits do not sit at a perfectly steady value. Normal changes can occur when equipment starts, stops or changes operating mode.
A practical alarm plan should define:
Which value triggers a warning
Which value triggers urgent review
Who receives the notification
How quickly someone must respond
What checks they should perform
How the event is recorded
When the alarm setting should be reviewed
The inspection response should suit the risk. A warning may prompt a planned inspection, load review or thermographic check. A more serious alarm may require prompt attendance and isolation planning.
Do not let the system assign a fault cause by itself. A high reading can point to a problem, but people still need to confirm the cause through inspection, testing and judgement.
Make the data easy to review
Many monitoring projects fail because the data is difficult to interpret. The system gathers values, but the team cannot quickly see what changed, where it happened or whether it matters.
Good displays use clear board names, circuit names and sensor locations. Labels such as `Sensor 14` or `Loop 3` may make sense during commissioning, but they are poor maintenance labels. Use names that match the switchboard schedule and site drawings.
Useful records include:
Sensor location
Circuit served
Normal operating range
Alarm history
Inspection notes
Corrective actions
Date of last review
Changes to connected load
This matters for handover as much as day-to-day operation. Maintenance teams change. Contractors change. A clear record lets the next person understand why a sensor exists and what its readings mean.
The best condition monitoring systems help people make decisions. They do not bury them in graphs.
Plan the rollout in stages
Existing boards vary in condition, construction and importance. A staged rollout lets the team learn before fitting monitoring across a wider group of boards.
A sensible first stage might focus on one or two boards with known value or known concern. That could include a main distribution board, a process-critical board, or a board with previous temperature findings.
During the first stage, check:
Sensor installation method
Communication reliability
Alarm levels
Dashboard labels
Event response process
False or unhelpful alarms
Maintenance team feedback
After a short operating period, review what happened. Did the readings make sense? Did alarms reach the right person? Were there nuisance alerts? Did the system identify anything worth acting on?
This review is where the monitoring approach improves. It may show that some alarm levels need changing, extra context is needed, or certain sensors are not adding value.
Keep protection, inspection and testing in place
Condition monitoring can support better maintenance, but it does not replace the basics.
Switchboards still need inspection, cleaning where appropriate, testing, thermal checks, protection verification and safe work practices. Monitoring can help target those activities and catch changes between scheduled visits.
It can also support asset planning. Repeated temperature concerns on a feeder may suggest a load review or termination redesign. Rising residual current trends may point to equipment ageing, moisture exposure or changes in connected loads. Communication faults may reveal installation issues that need attention.
The key is to treat monitoring as part of the maintenance system, not as a separate gadget. Readings, alarms and inspections should feed the same asset records and decision process.
The practical takeaway
Adding monitoring to existing switchboards can be worthwhile when it starts with the board, not the device catalogue. Review the drawings, history and known issues. Choose temperature and residual current points that match likely failure modes. Design the installation safely. Set alarms that lead to clear action.
Acrel monitoring equipment can form part of that approach, but the result depends on the full system around it: sensor selection, electrical design, commissioning, labelling, response and review.
The aim is simple. Give maintenance teams earlier evidence of change, show them where to look, and make sure the warning leads to a real inspection before a developing fault becomes an expensive failure.
