What are the benefits of MDPE sheathed cables?

MDPE stands for medium density polyethylene. This material is used principally as a sheathing material on larger size cables with higher voltage ratings, such as our BS6622 11kV MDPE sheathed cable.

Polyethylene materials all have excellent insulation resistance, dielectric strength, low dissipation factors, and abrasion resistance. They are classified by their density which is associated with the crystallinity levels of the polyethylene.  The higher the crystallinity or density, the greater the toughness of the cable sheath.

Why use MDPE cables

MDPE has very high resistance to abrasion: it is extremely hard and has a low dielectric constant with superior oxidation resistance. The hardness of the MDPE cable sheathing protects the cable from sharp objects dropped or loaded onto the cable. This means MDPE finds particular usage in transmission cables in the toughest of environments, notably those with the high ambient temperatures found in tropical and subtropical countries. At these high ambient temperatures alternative sheathing materials such as PVC would be soft and prone to damage easily during laying of the cables. When compared with LDPE (low density polyethylene) it has significantly more strength enabling it to be pulled under heavy load for cabling applications, whilst compared to HDPE (high density polyethylene) it has improved resistance to cracking.

Various additives can be applied to MDPE compounds to improve fire retardant properties, UV and weathering resistance and the chemical degradation.

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