Wires and cables are mainly prone to the following types of problems during long-term operation:
1. Insulation aging
This is the most common question. Long-term over-voltage operation of cables, being close to heat sources, being in corrosive environments, or being overloaded due to poor contact when laid side by side will all accelerate insulation aging. When installing accessories, the connection points are not tightly crimped and the contact resistance is too high, causing open flame overheating and insulation damage.
2. Accessory failure
The failure rate of intermediate joints and terminal heads is relatively high, mostly due to poor on-site installation workmanship. If there are bubbles, moisture or impurities left inside, it can easily cause partial discharge and eventually lead to insulation breakdown. Therefore, high-quality accessories must be selected and installation quality must be strictly controlled.
3. Damage to outer sheath
The outer sheath is the first line of defense for cables. Stabs from hard objects when directly buried, scratches during pipe laying, damage to surrounding construction, and even termite erosion (more common in the south) will damage the outer sheath. This will cause the insulation of the sheath to decrease and the metal sheath to be grounded at multiple points to generate circulating currents, which may cause thermal aging and breakdown of the insulation in the long term.
In order to ensure the safety of cable lines, it is necessary to rationally select the type, standardize the laying and installation, strengthen the monitoring of the operating environment and perform regular inspections, paying special attention to the insulation status, accessory connection points and the integrity of the outer sheath.