Industry research from major switchgear makers is consistent: most catastrophic switchgear failures do not start as insulation breakdown — they start as a connection that runs a few degrees too hot, for months. Understanding why, and why a once-a-year thermal camera scan is not enough, is now also a compliance question.
1. The under-rated threat: high-resistance connections
Equipment ageing, mechanical vibration, thermal cycling, harmonics, wrong material pairings and installation errors all drive the same outcome: high-resistance connection points. Because dissipated power follows P = I²R, such a joint generates localised heat even at rated current. That heat accelerates ageing, weakens nearby insulation, and materially raises the risk of arc flash — a direct threat to fire safety and to life.
2. Why periodic IR thermography is not enough
Relying on scheduled infrared (thermography) surveys alone has well-known, critical weaknesses:
- Snapshots, not trends: a survey captures one instant — often not when the equipment is at peak load, exactly when a marginal joint is hottest.
- High skilled-labour cost: it requires trained thermographers and scheduled access.
- Limited view: infrared (IR) windows narrow and distort the field of view; much of the connection is simply not visible.
- Deadly exposure: seeing the real joints often means opening an energised panel — direct arc-flash risk to the engineer.
- Invisible to meters: this kind of localised overheating cannot be detected by ordinary power or load metering.
3. Five core values of continuous thermal monitoring
| # | Value | What it delivers |
|---|---|---|
| 1 | Real-time diagnosis | Continuous 24/7 data; detects overheating and incipient faults immediately, and can be correlated against load current to diagnose the root cause — no outage, no waiting for the next survey. |
| 2 | No physical blind spots | Wireless sensor networks reach inside tight enclosures — busbars, ACB/MCCB terminals, hidden cable joints — so no thermal anomaly is missed and the fault is located precisely. |
| 3 | Improved safety | Remote data means engineers no longer approach energised equipment, sharply cutting arc-flash and accident risk. |
| 4 | Cost-effective over time | Less manual inspection labour, fewer catastrophic equipment failures and less production downtime through early detection. |
| 5 | Foundation for CBM | Continuous data is the essential input for condition-based / predictive maintenance — moving from reactive repair to proactive prevention (see our CBM & RBM guide). |
4. What the standards actually say
Continuous thermal monitoring is no longer just good practice — it is increasingly aligned with formal requirements. Two references matter, stated accurately:
NFPA 70B (2023)
With the 2023 edition, NFPA 70B became a standard (mandatory) rather than a recommended practice. It makes condition-based maintenance and thermographic inspection mandatory, on intervals set by each asset's physical condition — for example annual inspection as a baseline and more frequent (e.g. six-monthly) inspection for equipment in poorer condition. Critically, the standard also recognises continuous monitoring as a method to detect anomalies 24/7 between scheduled inspections and to inform maintenance intervals. In other words: periodic IR is the floor; continuous monitoring is the way to exceed it.
Always confirm the specific clauses and intervals against the current published edition of NFPA 70B for your jurisdiction and equipment.
EN 50110-1
EN 50110-1 — Operation of electrical installations — governs the safe operation of, and work on or near, electrical installations. Its core principle is to minimise human exposure to energised equipment and to make working procedures safe. Continuous, remote sensing supports that principle directly: it removes a recurring reason to open and approach live switchgear, which is exactly the hazard the standard exists to control.
5. How VTI delivers continuous thermal monitoring
The whole value above depends on a sensor that can actually sit on the energised joint, inside the enclosure, without batteries or wiring. VTI's self-powered wireless temperature sensors do exactly that:
- Self-powered — harvest energy from the conductor current; no battery to replace across thousands of points.
- Direct-contact, in-enclosure — clamp onto busbars, breaker terminals and cable lugs the IR camera cannot see.
- Live-line install — added without de-energising; no outage, no exposure.
- EMI-immune wireless — reliable data in MV/HV fields, into your gateway, SCADA and CMMS.
The result is the 24/7, blind-spot-free, safety-first thermal data that CBM/RBM and modern maintenance standards call for.
Meet the intent of NFPA 70B — continuously
Battery-free, in-enclosure wireless temperature monitoring that detects hot spots 24/7 and keeps engineers away from live equipment.
Request the technical datasheetFrequently asked questions
Does NFPA 70B 2023 require continuous thermal sensors?
Not exactly. NFPA 70B 2023 makes condition-based maintenance and thermographic inspection mandatory on condition-based intervals, and it recognises continuous monitoring as a valid method to detect anomalies 24/7 and inform inspection frequency. Continuous sensing exceeds the periodic-IR baseline rather than being explicitly mandated in its place.
Why isn't periodic infrared thermography sufficient?
It captures isolated snapshots — often not at peak load — needs skilled labour and scheduled access, is limited and distorted by IR windows, can't see inside enclosures without opening live panels (an arc-flash hazard), and misses overheating that ordinary metering cannot detect.
How does continuous monitoring improve safety?
Remote, continuous data removes the recurring need to open or approach energised switchgear for inspection, cutting arc-flash and accident risk — directly supporting the intent of safe-operation standards such as EN 50110-1.
How does this connect to CBM?
Continuous temperature is the essential input for condition-based and predictive maintenance: correlated with load and trended over time, it builds a real picture of asset health so teams shift from reactive repair to proactive prevention.