Shear Bolt Lug for MV Cable Terminations: Conductor Range, Palm Hole, and Accessory Compatibility

A shear bolt lug for MV cable must fit more than the conductor cross-section. It also sits inside a termination system, connects to a defined equipment stud or pad, and occupies limited space in a switchgear or transformer box. A lug that accepts the cable may still be unusable if its body is too large for the insulating component, its palm hole does not match the stud, or the installed cable cannot maintain the required routing and clearances.

The safest purchasing method is to treat the cable, lug, termination kit, and equipment interface as one assembly. The termination kit manufacturer’s current installation instructions and written compatibility approval should take priority over a general lug catalogue.

Five Selection Gates Before Model Approval

1. Match the Exact Conductor, Not the Family Headline

Begin with the cable manufacturer’s data sheet, then compare suitable designs in the mechanical lugs and connectors range. Record conductor material, nominal cross-section, construction, shape, and measured diameter after insulation removal. Two cables with the same square-millimetre rating can have different diameters and strand behavior. Do not assume that a lug listed for 95 mm² accepts every solid, stranded, compacted, or flexible 95 mm² conductor.

CONWELL lists its BLMT shear-bolt mechanical lug family for low- and medium-voltage terminations up to 35 kV, with a combined family range of 25–630 mm². This is not one universal lug. The published model bands are BLMT-25/95-13 for 25–95 mm², BLMT-35/150-13 for 35–150 mm², BLMT-95/240-13 for 95–240 mm², BLMT-120/300-17 for 120–300 mm², BLMT-185/400-17 for 185–400 mm², and BLMT-500/630-17 for 500–630 mm². Select from the exact row, then ask the supplier to confirm the offered model against the named cable.

CONWELL BLMT shear bolt lug. Model approval should use the exact conductor band, not the 25–630 mm² family headline.

If an insert, centering sleeve, or conductor preparation method is required, include its part number and installation instruction in the quotation. Never remove strands or substitute an unapproved insert simply to make a cable fit.

2. Check the Palm Hole and Equipment Pad as a Pair

The lug palm must match the actual equipment interface. State the stud nominal diameter and confirm the required clearance-hole diameter from the equipment drawing. Also record whether the pad uses one or two holes, the hole pitch, palm width and thickness, available edge distance, washer bearing area, tightening requirement, and terminal-pad material.

The CONWELL page publishes model suffixes ending in “13” or “17”, but an RFQ should not interpret a suffix as a guaranteed stud or hole size without a controlled dimensional drawing. Ask the supplier to state the finished palm-hole diameter for the exact offered reference. Field drilling, slotting, or enlarging can damage plating, reduce the bearing area, and invalidate the approved connection design.

The visible model marking and single-hole palm help receiving inspection, but the approved drawing must define the hole and palm dimensions.

3. Confirm Termination-Kit Compatibility in Writing

For MV work, a shear bolt lug for MV cable operates inside an electrical insulation and stress-control system. The mechanical cable lug application overview can support initial product screening, but the termination manufacturer must confirm the lug reference, cable reference, and kit reference as a compatible combination. A statement such as “suitable for MV” is not enough.

The compatibility check should cover lug body outside diameter, barrel length, overall installed length, palm offset, surface finish, bolt-head projection after shear, sealing cap or filler arrangement, and the internal bore of the insulating component. These details affect whether cold-shrink, heat-shrink, slip-on, or molded parts seat as designed and whether air pockets or sharp transitions are avoided.

Separable connectors may require a special threaded, spade, or solid-pin interface rather than a conventional flat palm. State the accessory type first and do not substitute between interface families based only on the conductor range.

The barrel diameter, bolt position, and installed bolt remnant form part of the accessory envelope; obtain the exact dimensional drawing before approval.

4. Verify Stress-Control and Cabinet Space

Check the complete installed assembly, not the loose lug. The termination kit must have enough axial space to cover the prepared cable and connector as instructed. The equipment box must accommodate the lug palm, stud hardware, phase barriers, insulation cover, and cable bend without forcing the termination sideways.

Ask for a drawing that shows cable entry, termination length, lug orientation, palm-to-stud position, closest grounded metal, phase-to-phase spacing, and access for the approved installation tool. For compact switchgear, transformers, or multiple cables per phase, a sample assembly or first-article fit check can resolve conflicts before shipment.

RFQ Data Sheet

Acceptance Records for the Installed Termination

• Record cable, kit, and lug references, batch or traceability codes, and phase identification.
• Photograph the prepared conductor, any installed insert, the completed shear heads, and the final palm connection.
• Confirm that every bolt sheared in the specified sequence and that no strand, burr, damaged plating, or sharp bolt remnant remains.
• Record equipment-bolt tightening with the value and tool required by the equipment manufacturer.
• Verify termination-component position, seal, clearances, cable support, and final enclosure condition.

Do not use the shear-head break as evidence of equipment-stud torque. The shear bolt secures the conductor inside the barrel; the palm-to-equipment fastener is a separate joint governed by the equipment instructions.

Frequently Asked Questions

Does a published conductor range cover every cable construction within those sizes?

No. A cross-section range does not automatically confirm solid, stranded, compacted, sector-shaped, or flexible conductors. Submit the cable data sheet and actual conductor diameter, then obtain model-specific confirmation of the supported construction and any required insert.

Do the “13” and “17” suffixes confirm the finished palm-hole diameter?

Do not approve the hole from the suffix alone. Request a controlled drawing that states the finished hole diameter, palm width, thickness, length, and offset for the exact offered reference, then compare it with the equipment stud and terminal-pad drawing.

Can any shear bolt lug for MV cable be used with any termination kit?

No. The termination manufacturer must confirm the cable, lug, and kit as a compatible combination. Body diameter, overall length, bolt remnant, surface condition, palm position, insulating-component bore, and stress-control geometry can prevent an otherwise suitable conductor connection from fitting the accessory.

Is a completed shear-head break enough to accept the installation?

No. It indicates completion of a designed bolt action only when the correct model, cable preparation, insert, bolt sequence, and tool conditions were used. Acceptance should also cover conductor condition, bolt remnants, accessory position, sealing, clearances, cable support, traceability, and the separately tightened equipment fastener.

What CONWELL Can Confirm for Your Project

The published BLMT page identifies a high-strength aluminium-alloy body, aluminium-alloy bolts, and a tin-plated surface. Project approval still requires model-specific drawings and confirmation of conductor construction, accessory fit, and equipment interface.

For a model and compatibility check, send CONWELL an MV lug enquiry with the cable data sheet, termination-kit reference, equipment drawing, quantity, and required approval documents. This gives engineering and procurement one traceable basis for selection and quotation.