JZD Wire & Cable Factory
More Than 20 Years Experience
More Than 20 Years Experience
Author: Joey Wan 
December 24,2021
According to relative report, the most direct cause of THHN stranded wire or cable failure is breakdown caused by the degradation of insulation layer. However in fact there are many method to reduce insulation degradation problems. According to our practical operation experience in the industry for more than ten years, we can sum up the following situations and let's look at them together.
There are many factors leading to external damage of cables, such as unqualified thhn stranded wire or cable laying and installation structure, excessive wiring and other factors can lead to mechanical damage, and it is easy to affect the normal operation of underground thwn wires or cables, such as cable damage in civil and industrial buildings. Sometimes, if the damage degree is not serious, it may take months or even years to make the damaged parts completely damaged, and sometimes even serious short circuit fault may occur, which directly affects the safety of electrical equipment production.
Substandard nylon cable joints and joints in wet weather, which can produce water or steam under prolonged electric field. The formation water mixed with the trees and the strength of the insulation gradually caused thhn stranded wire or cable damage. Resistant to the moisture is the one of most basic ability for a qualified thwn wire underground.
Due to current overload operation, the thermal effect of the load current through the thhn stranded wire and cable will inevitably cause the conductor to heat up. At the same time, skin effect, eddy current loss of charge and electrical loss of steel armored will also generate extra heat in the thwn wire underground, thus raising the cable temperature, and eventually lead to failure of thhn stranded wire or cable. If it cannot be handled properly at the first time, it is necessary to stop operation immediately to avoid more serious accidents.
The thhn stranded wire joint is the weakest link caused by the cable joint failure and direct fault. The construction worker's cable joints are manufactured in a way that if they are not tightly crimped and heated inadequately, the insulation of the cable ends can be reduced and accidents can occur. Equipment, precision testing instruments, raw materials, production quality control are important for manufacturing a qualified thwn wire underground. What's more compared to the thhn wire in the conduit, it's more complicated to produce the thwn wire underground, the price is higher, so more purchaser and buyer preferred to purchase the thhn wire in the conduit.
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