Efficient and Effective

Composite Shell Joint Retrofit Trial

Project Data

Start date:


End date:





Joint Shell developed a safe, cost effective alternative to removal and replacement of defective LV joints, lowering the unit cost per repair. The project innovated an existing jointing technique which involved encapsulation of joints in resin-filled plastic shells. Traditionally this approach was only adopted on new joints, but the Joint Shell project adapted this technique to repair existing, defective LV branch (T) joints.

What is the project about?

An increasing number of defective joints had been discovered within the pits ranging from a loss of insulation to a loss of earth. Traditionally, defective low voltage joints were removed and replaced following a fault which can require a large excavation and live jointing. This reactive approach can lead to Customer Minutes Lost (CMLs) and Customer Interruptions (CIs). This project developed a safe, cost effective alternative to repair defective joints.

How we’re doing it

The project researched the existing market, designed, developed and trialled an LV jointshell which could be installed on an LV joint to avoid moisture ingress inside the joint and its failure. Plastic shells were designed and developed in conjunction with the supplier. They were encapsulated to be wrapped up on an LV joint to avoid moisture ingress into the joint.

The compatibility of the polyurethane resin (JEM Resin) with bitumen compound will be explored at this stage. It was proposed to contact existing resin/shell producers to gain an understanding of the  limitations of the resin and carry out trials where required.

What makes it innovative

The design of an LV joint shell was innovative and has never been trialled before to prevent LV joint failure within GB networks.

The project demonstrated that a new type of joint shell can protect an LV joint from failure and water ingress. A network triall carried out by our team confirmed this.

What we’re learning

Joint Shell had a real effect on site safety – allowing field engineers to remove and replace defective joints ahead before  major faults occurred, thus reducing the risks associated with a major fault on the network.

Joint Shell also lowered the cost per unit of LV fault replacement, which saved time for engineers out in the field and money for UK Power Networks’ customers.

thinking outside the box icon
Share your ideas

If you have an idea that could reshape or revolutionise the way we work, we want to hear from you.

Submit an idea