What Is a Resin Cable Joint? Splice Kit Types and Selection Criteria
A resin cable joint is a cable splice kit that covers the splice of a low-voltage power cable with insulating resin poured into a mould and seals it against moisture.
A resin cable joint (resin cable splice kit) is a splice set that covers the splice of low-voltage power cables with insulating resin poured into a plastic mould and seals it against moisture. Once the resin cures and hardens, it provides the insulation and sealing of the splice. It is used to extend cables that are buried, run in ducts or installed in damp locations, and to repair a damaged section of cable.
Types of cable joints
| Type | How it insulates | On site |
|---|---|---|
| Resin (cast) joint | Resin poured into the mould cures around the splice | No heat source needed; the resin must be left to cure |
| Heat-shrink joint | Tubes and sleeves shrink over the splice when heated | Needs a hot air gun or gas torch |
By voltage class: 1 kV class joints are for low-voltage cables. Medium-voltage cables use MV joints of a different design with screening and field control; a 1 kV kit does not replace them.
Selection criteria
- Number of cores and cross-section: The kit must match the cable construction. 3x25+16 means three 25 mm² phase cores and one 16 mm² neutral core; 4x16 means four equal 16 mm² cores. Compare the marking on the cable sheath with the construction in the kit name.
- Voltage: The kits in the catalogue are 1 kV class and are used on 0.6/1 kV underground cables such as NYY.
- Conductor material: The names of the 3x25+16, 3x50+25 and 3x70+35 kits in the catalogue state copper conductors. Aluminium-conductor cables need connectors suitable for aluminium; confirm the kit's suitability with the manufacturer.
- Conductor connection: The cores are joined with crimp connectors before they go into the mould. Check on the product page whether the connectors come with the kit; if not, buy splice connectors matching the core cross-section separately.
- Cable outer diameter: The entries at both ends of the mould must fit the cable's outer diameter. For a cable with a thick sheath, check the kit size in the product data.
Common mistakes on site
- Lining up the core connectors: If the connectors are not staggered, the splice area gets thicker, does not fit the mould, and the resin layer between the connectors becomes thin.
- Mixing the resin poorly: If the two components are not mixed as instructed, the resin does not cure fully and gives no insulation or sealing.
- Not preparing the sheath: If the part of the sheath inside the mould is not cleaned of grease and dirt and roughened, the resin does not bond to it and moisture travels along the joint.
- Burying or loading before curing: Curing takes longer in the cold; the time is in the manufacturer's instructions.
- Working on a wet splice: Water left on the cores or in the mould weakens the insulation.
Resin cable joints in the catalogue
The Resin Cable Splice Kits category has 6 active products; all are Tamer Elektrik E1 series, 1 kV class, and are sold by the piece.
| Cable construction | Stock code |
|---|---|
| 4x4 mm² | E1 4105 |
| 4x16 mm² | E1 416 |
| 3x25+16 mm² | E1 32516 |
| 3x35+16 mm² | E1 33516 |
| 3x50+25 mm² | E1 35025 |
| 3x70+35 mm² | E1 37035 |
Frequently asked questions
Can a resin cable joint be buried?
Yes; resin joints are made for cables underground and in damp locations. Bury the joint only after the resin has fully cured.
What does 3x25+16 mean?
It shows that the cable has three 25 mm² phase cores and one 16 mm² neutral core. The joint kit is chosen for a cable of the same construction.
Can a resin joint be used on a medium-voltage cable?
No. 1 kV class kits are only for low-voltage cables; medium-voltage cables need an MV joint.
How long does the resin take to cure?
It depends on the resin type and the ambient temperature; follow the manufacturer's instructions on the pack. Curing takes longer in cold weather.