Have you ever considered the continuous stress that cables hidden from sight—running inside walls, underground, or even on roofs—are exposed to? The aging of electrical networks, environmental factors, and mechanical damage all degrade the cable sheathing. The primary diagnostic tool is insulation resistance testing, which can detect faults before they lead to a disaster.
Why shouldn't this testing be neglected?
Insulation degradation is not visible to the naked eye. A weakened section can cause leakage current to appear, which:
- Can cause electric shock accidents on inadequately protected enclosures.
- Can cause fires due to localized heating and arcing.
- Causes unexpected downtime and costly operational losses in production.
This testing provides an accurate picture of whether the cable insulation is still capable of withstanding the mains voltage.
What do the standards require?
Testing is required not only by common sense but also by strict national and international standards.
- Indoor electrical installations
The initial and periodic verification of low-voltage electrical installations is regulated by the MSZ HD 60364-6 standard. During the installation or modification of a network, insulation resistance testing is a mandatory part of the initial verification.
- Underground cables and power cable lines Cables laid underground or installed outdoors fall under the scope of MSZ 13207. These cables can only be tested with specialized measuring instruments; an average electrical installation tester is unable to charge them with sufficient energy to accurately test a cable at the prescribed voltage.
- PV systems
On the DC (direct current) side connecting the solar panels, voltages of 600 V or even 1000-1500 V often run in the open air. The MSZ EN 62446 standard mandates the verification of the insulation resistance of PV strings. Here, cables are exposed to UV radiation, rodents, and extreme weather conditions. Damaged insulation on the DC side not only causes efficiency loss (leakage current) but, due to the resulting DC arc, it is the most common cause of solar panel fires.
How is the testing performed in practice?
Professional diagnostics is unimaginable without reliable measuring instruments. Our professional measuring tools provide precise results even in the harshest industrial and field conditions. Our modern digital devices automatically perform the charging of the cables prior to the measurement, the testing itself, and the discharging of the cable at the end of the test, thereby protecting the technician from dangerous electric shocks. When inspecting solar systems, our specialized tools allow for safe and fast work on the DC side as well; with their help, hidden ground faults of the strings running on the roof can be located immediately.
The testing process with the instrument follows a strict sequence:
- De-energization: The most important step is disconnecting the network (or the inverter).
- Disconnecting loads: All sensitive electronic equipment must be disconnected to prevent the high test voltage from destroying them.
- Measurement configuration: The test leads of the Fluke instrument must be connected between all active conductors, as well as between the conductors and the protective earth (PE) / cable shield.
- Evaluation and documentation: The obtained values must be recorded. It is important to note that the cable insulation resistance test report is an independent, separate document, which does not replace the general verification documents of the electrical installation.
Summary
Insulation resistance testing is the cornerstone of operational safety – whether it is in the walls of a family house, an underground cable of a factory, or a roof-mounted solar park. Diagnostics performed with a professional instrument help prevent millions in damages and life-threatening emergencies. Don't wait until a fuse trips or the smell of smoke warns you of trouble – have your network inspected in time, in accordance with current standards!
Is your electrical network safe? Don't leave it to chance!
Whether your new solar system has just been completed or you want to ensure the safety of your existing industrial network, professional insulation testing cannot wait. Our team performs comprehensive diagnostics using the latest, calibrated professional measuring instruments and up-to-date knowledge of standards, and issues the official test report.
