Loose or degraded contacts, poor preparation, corrosion, overloaded circuits and unequal phase loading can contribute to termination heating. Compare similar phases and operating conditions, and arrange authorized inspection when a hotspot is suspected.
What the symptoms may suggest
Use this table to organize evidence. One observation is not enough to confirm a fault.
| Observation | Possible area | Useful evidence |
|---|---|---|
| One termination hotter than similar phases | High contact resistance or local defect | Thermal record at comparable load and geometry |
| Whole cable and all ends run hot | High current, cable rating or installation condition | Load history, derating and cable data |
| Temperature changes after maintenance | Contact quality or assembly issue may be involved | Work history, specification and follow-up trend |
| Heat plus smell or discolouration | Potential serious insulation and connection damage | Protect the area and escalate for qualified response |
Understanding the fault
Contact resistance produces local heat
At a poor electrical connection, additional resistance increases heat loss. The same joint can deteriorate faster as the contact condition worsens. A single hot termination should prompt a review of the connection and its history.
Compare like with like in thermal surveys
Apparent temperature depends on surface emissivity, reflected radiation, load and camera position. Compare similar connections under comparable conditions and keep the instrument settings in the report. A thermogram is useful screening evidence, not proof of a particular defect.
LT and HT terminations need different procedures
MV and HV cable accessories introduce additional insulation, stress control and sealing considerations. For 11 kV and 33 kV cables, design and repair decisions must follow the accessory manufacturer and site authorization. Do not apply generic LT joint practices.
Five questions to narrow the problem
Use existing records where possible. Site testing belongs to trained and authorized personnel.
- Which phase and termination shows the abnormal trend?
- Were thermal images captured at comparable load and viewing conditions?
- What are the cable type, voltage class and termination model?
- Was there recent jointing, maintenance or water ingress?
- Are there any signs of charring, tracking or insulation damage?
Next decision
Treat a marked hotspot as a potential maintenance priority. Do not access exposed live cable terminations. The authorized team should assess the load, joint condition, accessory rating and repair plan using approved procedures.
Common questions
Does every hot termination have a loose lug?
No. Overload, corrosion, insulation or thermal measurement effects can also contribute.
Can a normal phone camera detect cable termination heat?
A normal visible-light camera cannot measure a thermal hotspot. A suitable thermal instrument and competent interpretation are needed.
Technical references
These references explain the general principles. Follow the actual equipment manual and local safety requirements.
- Fluke: electrical thermography and hot connections
- Fluke: measurements for electrical fire prevention
Need help documenting the fault?
Electrical Doctor collects symptoms and creates a preliminary record. It cannot authorize repairs, switching or work on live parts.
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