JBB Type Hot-Dip Galvanized Iron Parallel Groove Clamp
The JBB type iron parallel groove clamp is a bolted splicing fitting designed for the parallel connection or branch connection of galvanized steel strand and compatible steel wire. It is primarily used at non-tension-bearing positions in overhead distribution lines, overhead earth-wire systems and related utility installations.
The clamp consists of a grooved lower body, matching pressure plate, threaded bolts, nuts and washers. Tightening the fasteners presses the two conductors into the parallel grooves, producing a stable mechanical connection and maintaining electrical continuity where required by the approved line design.
The JBB series normally includes JBB-1, JBB-2 and JBB-3 models. Each model is designed for a specified conductor-diameter range and uses either two or three clamping bolts. The exact model must be selected according to the actual conductor diameter rather than conductor cross-sectional area alone.
Important: This clamp is normally intended for non-tension-bearing connections. It must not replace a dead-end clamp, tension clamp or full-tension splice unless the exact product has been designed and tested for that purpose.
Key Features
- Parallel-groove structure for steel strand connections
- Suitable for non-tension-bearing splicing and tapping
- Bolted construction allows installation and inspection with standard tools
- Grooved body supports consistent conductor positioning
- Available with two-bolt or three-bolt configurations
- Hot-dip galvanized finish for outdoor corrosion protection
- Multiple JBB models available for different conductor diameters
- Dimensions, coating and packaging can be produced to approved drawings
Representative Model Specifications
| Model | Applicable Steel-Strand Diameter | Body Width B | Bolt Size | Length L | Groove Radius R | Height H | Bolts | Approx. Weight |
|---|---|---|---|---|---|---|---|---|
| JBB-1 | 6.6–7.8 mm | 44 mm | M12 | 90 mm | 4.5 mm | 50 mm | 2 | 0.62 kg |
| JBB-2 | 9.6–11.0 mm | 50 mm | M16 | 90 mm | 6.0 mm | 60 mm | 2 | 0.82 kg |
| JBB-3 | 13.0–14.0 mm | 56 mm | M16 | 124 mm | 7.0 mm | 65 mm | 3 | 1.90 kg |
The table contains representative industry dimensions. Final conductor range, dimensions, tolerances, bolt grade and weight must be confirmed using the manufacturer’s approved drawing.
Materials and Construction
| Clamp Body | Malleable cast iron or specified ferrous casting |
|---|---|
| Pressure Plate | Malleable cast iron or specified ferrous casting |
| Bolts and Nuts | Carbon steel |
| Washers | Galvanized steel |
| Surface Finish | Hot-dip galvanized |
| Connection Type | Bolted parallel connection |
| Mechanical Function | Non-tension-bearing splice or branch connection |
The body and pressure plate are commonly manufactured from malleable-iron castings. The groove profile must correspond to the specified steel-strand diameter to distribute clamping pressure and prevent excessive localized deformation.
Material composition, casting grade, fastener grade and mechanical properties must be confirmed by the approved product specification. “Forged steel” should not be stated unless supported by the actual manufacturing record.
Hot-Dip Galvanized Protection
The ferrous components are normally hot-dip galvanized to improve corrosion resistance in outdoor power-line environments. The zinc coating should be continuous and reasonably smooth, without exposed base metal, excessive deposits or defects that interfere with assembly.
Coating thickness, zinc mass and test method should be specified in the purchase contract. ISO 1461 may be used as a coating reference when it is applicable to the product and agreed by the customer.
Typical Applications
- Parallel connection of galvanized steel strand
- Branch or tap connection of compatible steel wire
- Overhead earth-wire and shielding-wire assemblies
- Non-tension-bearing connections in distribution lines
- Utility-pole and substation steel-wire connections
- Maintenance and reconstruction of existing overhead lines
Installation Guidance
- Confirm the conductor material and outside diameter.
- Select the JBB model whose groove range matches the conductor.
- Inspect the clamp body, grooves, bolts, nuts and galvanized coating.
- Remove loose dirt, heavy oxidation and other contamination from the conductor contact area.
- Place the two conductors correctly inside the parallel grooves.
- Install the pressure plate and start all nuts by hand.
- Tighten the bolts alternately and evenly to the specified installation torque.
- Verify that the conductors remain seated in the grooves and that the pressure plate is not tilted.
- Inspect the connection after installation and during scheduled line maintenance.
Do not use an unspecified tightening torque. Excessive torque may damage the clamp, threads or conductor, while insufficient torque may result in movement, heating or loss of electrical continuity.
Quality Inspection
- Material and casting-quality inspection
- Conductor-groove dimensional inspection
- Overall dimensions and bolt-hole inspection
- Thread fit and fastener assembly inspection
- Hot-dip galvanized coating appearance and thickness inspection
- Mechanical clamping or slip testing when specified
- Electrical resistance and temperature-rise testing when applicable
- Marking, quantity and packaging inspection
Reference Standards
- DL/T 758-2021 – Splicing fittings
- IEC 61284:1997 – Overhead lines – Requirements and tests for fittings, when applicable
- ISO 1461:2022 – Hot-dip galvanized coatings on fabricated iron and steel articles
- Applicable utility drawings and customer technical specifications
Listing a reference standard does not constitute certification. Compliance must be supported by inspection records and test reports for the exact product model.
Ordering Information
Please provide the following information when requesting a quotation:
- Required model: JBB-1, JBB-2 or JBB-3
- Steel-strand material and outside diameter
- Required body and pressure-plate material
- Bolt size, strength grade and quantity
- Required hot-dip galvanized coating specification
- Applicable drawing or technical standard
- Required mechanical and electrical tests
- Order quantity, marking and packaging requirements
Frequently Asked Questions
Can this clamp be used for aluminium conductor?
The standard JBB iron parallel groove clamp is primarily intended for steel strand or compatible steel wire. Aluminium conductors normally require a suitable aluminium-alloy parallel groove clamp. Do not mix conductor and clamp materials without an approved technical design.
Is the JBB clamp a tension-bearing fitting?
It is normally used as a non-tension-bearing splicing or branch fitting. It should not be used as a dead-end or full-tension connection unless the exact model has been tested and approved for that function.
How should the correct model be selected?
Select the model according to the actual conductor outside diameter, groove dimensions, number of bolts and approved line drawing. Model selection should not be based on appearance alone.
Is the product hot-dip galvanized?
Hot-dip galvanizing is the normal finish for this type of outdoor iron fitting. The required coating thickness and inspection method must be stated in the purchase specification.
Can the clamp be reused?
Reuse is not recommended without inspection. A previously installed clamp may have damaged threads, distorted grooves, worn galvanizing or reduced clamping performance.
