Article by Prysmian Cables 4th Sept 2017
(Original Article)

While our contractual guarantee for cables is 12 months from delivery electricians, electrical engineers and their clients can be confident that Prysmian cable will have a design life of 25 years or more.

A cable’s design life is based on the cable running at maximum load all day every day for 25 years. At maximum load, the cable conductor will be at its maximum temperature, normally either 70℃ or 90℃, depending on the cable’s grade of insulation and it’s BS specification.

If the cable is not fully loaded all of the time then it can be expected to exceed its design life. For example, if the cable is loaded for 8 hours in a day, its life expectancy could be in excess of 40 years. However, if a cable were to be operated at 15℃ higher than its stated maximum operating temperature, then its life expectancy could be less than 5 years.

There are many factors that determine the life of a cable including:

• Whether a cable has been de-rated where it is installed next to other circuits or heat sources that would otherwise make it operate at a higher temperature
• Damage to the cable during transport or installation
• The presence of water
• Chemical contamination
• UV or infra-red radiation
• The number of times that cable is overloaded
• Number of short circuits
• The effect of harmonics
• The temperature at terminations
• Temperature of the cable
• Whether the cable has been installed internally of externally
• Service life load

Of course, there is no definitive or simple calculation method that can be used to forecast the actual life expectancy of a fixed wiring cable, but by following best practice electricians and designers can be sure that Prysmian’s high-quality cables will meet and exceed their design life.