By eNarayan Elex’s technical sales team – authorized Raychem RPG cable accessories distributor serving Hyderabad, Telangana and Andhra Pradesh. Last updated 21 August 2026.
Quick Answer
Raychem RPG heat-shrink cable jointing kits are selected on three variables, in this order: voltage class of the cable (LT/LV up to 1.1 kV, or MV 11 kV / 22 kV, or HT 33 kV), joint type (straight-through joint to connect two cable runs, or termination/end-seal to land a cable onto switchgear, a transformer or a panel), and conductor cross-section (kits are supplied in size bands – commonly quoted from around 16 mm² up to 630 mm² across the LT/MV range, some MV families extending further – not a single size, so the kit must bracket the actual cable’s mm² rating). Get any one of these three wrong and the kit will not perform to its design life even if it appears to “fit.”
Why the Right Kit Matters
A cable joint or termination is the weakest point in any LT/HT cable run – more insulation failures originate at a joint than along the cable body itself. Heat-shrink technology (the Raychem RPG approach) replaces older taped/compound joints with a pre-engineered kit: dual- or triple-wall heat-shrink tubing with an adhesive/void-filling liner, a stress-control layer to manage the electric field at the cable-core cutback, and grounding/shielding components – assembled to a fixed, repeatable specification rather than built up by hand from raw tape and compound. That consistency is exactly why the kit has to match the cable it is going on to.
Step 1 – Confirm the Voltage Class
Raychem RPG’s jointing and termination range is organised by voltage class, and this is the first filter:
| Voltage class | Typical designation | Cable types covered |
|---|---|---|
| LV / LT | Up to 1.1 kV | PVC / XLPE / rubber-insulated LT power and control cables |
| MV | 11 kV | XLPE/PILC medium-voltage distribution cables |
| MV | 22 kV | XLPE/PILC medium-voltage distribution cables |
| HT | 33 kV | XLPE/PILC medium-voltage distribution cables (upper end of the MV/HT band) |
| HV (outdoor termination range) | Above 33 kV, up to 220 kV at the top end | Sub-transmission/transmission cable – beyond eNarayan’s typical LT/11kV/33kV supply band |
A kit rated for one voltage class must never be substituted on a cable of a different class – the stress-control geometry and creepage/clearance design inside the kit is specific to the working voltage. If your cable’s nameplate or drawing says 11 kV, 22 kV or 33 kV, you are in the MV/HT range; general LT wiring and distribution circuits up to 1.1 kV stay in the LV/LT range.
Step 2 – Straight-Through Joint vs Termination
These are two different products and are not interchangeable:
- Straight-through joint (in-line joint): used to connect two lengths of cable end-to-end – for cable runs that are longer than a single manufactured drum length, for a repair after cable damage, or to extend a run. The kit reinstates full insulation and screening continuity across the joint so the spliced section performs identically to unbroken cable.
- Termination / end-seal kit: used where a cable run ends and has to be landed onto a live component – a switchgear panel, an RMU, a transformer bushing, a motor terminal box or a distribution board. Termination kits are supplied for both indoor and outdoor use (outdoor terminations add UV- and tracking-resistant sheds/skirts for open-air installation); Raychem RPG’s outdoor termination range extends well beyond the LT/11kV/33kV band eNarayan typically supplies for.
Specifying the wrong type on a bill of materials is the single most common ordering error on site – always confirm from the drawing whether the point in question is mid-run (joint) or an end connection into equipment (termination).
Step 3 – Match the Conductor Size Band
Raychem RPG heat-shrink kits for LT and MV/HT XLPE cable are commonly supplied across a conductor size range from roughly 16 mm² at the small end up to 630 mm² (some MV/HT termination/joint families extend further at 11-33 kV and above). Kits are NOT sold per exact mm² – they are supplied in overlapping size bands (a single kit part number typically covers a defined mm² range), so:
- Read the actual conductor cross-section off the cable drawing or the cable’s own printed marking – never estimate from outer diameter alone, especially on multicore cable.
- Match that mm² figure to the kit’s stated size band, not just its voltage class. A kit correct for voltage but wrong for size band will not fully shrink down onto a conductor that’s outside its design range, compromising the seal.
- For a mixed-size joint (two different conductor sizes on either side, e.g. during a cable upgrade), a transition/reducer joint kit is required rather than a standard same-size kit.
Selection Table by Kit Family (Overview)
The table below is a working reference for the three variables together – voltage class, cable size band, and conductor type – so a site engineer can narrow the family before checking the exact part number against the current Raychem RPG datasheet.
| Voltage class | Conductor type | Typical cross-section band | Joint family | Termination family |
|---|---|---|---|---|
| LT (up to 1.1 kV) | Single-core / multicore XLPE, PVC | ~16-400 mm² | LT heat-shrink straight-through joint | LT heat-shrink indoor termination |
| 11 kV | Single-core XLPE/PILC | ~16-400 mm² | 11 kV heat-shrink straight joint | 11 kV indoor / outdoor termination |
| 11 kV | Three-core XLPE/PILC | ~25-400 mm² | 11 kV three-core joint | 11 kV three-core indoor/outdoor termination |
| 22 kV | Single/three-core XLPE | ~35-400 mm² | 22 kV heat-shrink joint | 22 kV indoor/outdoor termination |
| 33 kV (HT) | Single/three-core XLPE | ~35-630 mm² | 33 kV heat-shrink joint | 33 kV indoor/outdoor termination |
Exact mm² breakpoints, kit part numbers and whether a given family covers single-core or three-core (or both) construction vary by the specific product line and are confirmed against the current Raychem RPG datasheet at the point of order – the table above is a selection starting point, not a substitute for the datasheet.
Step-by-Step Jointing Procedure – Overview
This is a high-level sequence to understand what a heat-shrink joint installation involves; it is not a substitute for the specific installation instruction sheet supplied inside every Raychem RPG kit, which must be followed exactly for the part number in hand.
- Isolate and confirm dead. Standard electrical safety procedure – isolate, lock out/tag out, and prove dead with a rated voltage detector before any cable preparation begins.
- Cut back the outer sheath and armour to the dimensions specified in the kit’s instruction sheet – cutback lengths are kit-specific and printed on the datasheet, not universal.
- Prepare the conductor ends – strip insulation to expose bare conductor for the connector, clean any semi-conductive screen residue, and dress the cable so the components will sit square and true.
- Slide on the components in the sequence shown on the instruction sheet before making the conductor connection – this is the step most often gotten wrong on site, because once the conductor is jointed, components can no longer be threaded over the cable.
- Crimp or mechanically connect the conductor using the connector supplied or specified in the kit (correct die and crimp tool for the connector size).
- Apply void-filling/insulating mastic or tape around the connector as specified, to eliminate air gaps under the stress-control layer.
- Position and shrink the stress-control tubing over the cable-core cutback first – this component manages the electric field concentration at the screen cut point and must be centred exactly per the instruction sheet.
- Shrink the main insulating sleeve over the joint body, working from the centre outward with a controlled-heat torch, until full recovery and a glossy, bubble-free surface is achieved.
- Reinstate the metallic screen/earth continuity using the copper mesh, braid or bonding strap supplied, connecting screen-to-screen across the joint.
- Apply the outer protective/moisture-barrier tubing (and armour-bridging components for armoured cable) and shrink to full recovery.
- Reinstate mechanical protection – armour clamps, cable protection boxes or duct sealing as required by the installation environment (buried, duct, tray, or panel entry).
- Visual inspection and (where specified) insulation resistance / continuity test before re-energising.
The two steps most linked to premature joint failure on site are #4 (component sequence) and #7-8 (stress-control positioning and shrink quality) – both are covered in more detail below under common failure causes.
Common Failure Causes at Joints
Understanding why joints fail – rather than just how to make one – is what separates a joint that lasts the cable’s design life from one that becomes a repeat callback.
- Incomplete or off-centre stress control. The stress-control tube (or stress-control mastic/patch on some kit designs) manages the electric-field concentration where the semi-conductive screen is cut back. If it is positioned off-centre, under-length, or doesn’t achieve full shrink recovery, the field concentrates at an uncontrolled point and partial discharge activity begins there – often invisible until the joint fails months or years later.
- Moisture ingress through an incomplete outer seal. A heat-shrink outer sleeve that hasn’t reached full recovery (patchy, wrinkled, or under-heated) leaves a path for moisture to track in, especially on buried or duct-run joints exposed to groundwater. Moisture ingress is one of the two most commonly cited long-term joint failure mechanisms alongside stress-control faults, and it is largely preventable by correct heating technique and inspection at installation.
- Voids at the connector interface. Skipping or under-applying void-filling mastic/tape around the mechanical connector leaves air pockets. Under electrical stress, air-filled voids are where partial discharge starts, which over time carbonises the surrounding insulation and leads to breakdown.
- Wrong kit for conductor size or voltage class. Covered in Steps 1 and 3 above – using a kit outside its designed mm² band or voltage class means the components can’t achieve their intended fit and clamping force, undermining the whole design.
- Mechanical damage during installation. Nicking the conductor or insulation during stripping, over-torquing a crimp connector, or physically stressing the joint before the sleeves have fully cooled and set, all introduce weak points that show up later as failures, sometimes on re-energisation, sometimes months down the line under thermal cycling.
- Inadequate cable bending radius near the joint. Bending the cable too tightly right at the joint body stresses the insulation and the joint components simultaneously – manufacturer minimum bend radius guidance applies at and near a joint, not just along straight cable runs.
Heat-Shrink vs Cold-Shrink vs Push-On – Comparison
Three broad jointing/termination technologies are used in the LT/MV/HT cable accessory market. eNarayan’s Raychem RPG range is predominantly heat-shrink, but it’s useful to understand where the alternatives fit so a specification decision is made deliberately rather than by default.
| Factor | Heat-shrink (Raychem RPG) | Cold-shrink | Push-on / pre-moulded |
|---|---|---|---|
| Installation method | Components pre-expanded on a removable core or applied loose, then shrunk with a controlled heat source (torch) | Components pre-stretched on a removable core, installer pulls the core out and the material shrinks at ambient temperature – no heat/flame needed | Rubber or silicone components mechanically slid/pushed onto the prepared cable to an interference fit – no heat, no core removal |
| Skill/tooling dependency | Requires correct torch technique, controlled heating, trained installer – heat-shrink quality is installer-dependent | Lower installer-dependency since there’s no flame/heat step, but core-pull technique and component positioning still matter | Lowest installer variability once cable prep is correct – fit is largely mechanical/dimensional |
| Site conditions | Needs a safe hot-work permit/environment for the torch – a consideration in confined spaces, near gas lines, or where hot work permits are restrictive | Preferred where hot work is restricted or prohibited (confined spaces, explosive-atmosphere-adjacent areas, indoor panels with hot-work limits) | Also suited to hot-work-restricted environments; commonly used for pre-engineered/factory terminations |
| Fit range / flexibility | Wide size-band tolerance per kit (covers a mm² range), good for irregular/aged cable outer diameters | Narrower per-kit size tolerance than heat-shrink in some product lines – matched more tightly to a specific OD range | Typically the tightest OD-dependent fit – best suited to new, consistent-diameter cable and standardised terminations |
| Track record / cost profile | Long-established in India for LT/MV/HT distribution; broad availability, this is the dominant technology eNarayan stocks | Growing usage, generally at a cost premium per kit vs heat-shrink for equivalent voltage class | Common on pre-moulded MV terminations at higher voltage/HV where speed and repeatability at the top end matter |
For eNarayan’s LT/11kV/33kV distribution-cable customer base, heat-shrink remains the default recommendation on cost, stock availability, and long field track record in this size/voltage range. Cold-shrink or push-on becomes relevant primarily where hot-work restrictions on a specific site rule out a torch – this is a project-specific conversation, not a blanket substitution.
Standards Referenced
Cable jointing and termination practice for XLPE/PVC power cable in India is governed by the relevant Bureau of Indian Standards (BIS) specifications for the cable itself (XLPE cables to IS 7098, PVC cables to IS 694/IS 1554 as applicable) and by the cable accessory’s own type-test standards, several of which are aligned to IEC practice. Always cross-check the specific IS/IEC reference printed on the Raychem RPG datasheet for the exact kit part number you are quoting, rather than relying on a general IS citation – accessory standards vary by kit family and are confirmed at the point of order.
For related site work, see our guides to switchgear selection (MCB, MCCB, RCCB, ACB) and earthing & lightning protection (IS 3043, IS/IEC 62305), both relevant where a cable jointing/termination scope overlaps with panel or earthing work on the same site.
Quick Selection Checklist
- Voltage class confirmed from cable nameplate/drawing (LT/1.1kV, 11kV, 22kV, or 33kV/HT)
- Joint type confirmed: straight-through (mid-run) vs termination (end connection)
- If termination: indoor or outdoor confirmed
- Conductor size (mm²) read from cable marking/drawing, not estimated
- Kit size band brackets the actual conductor mm²
- Same-size joint vs transition/reducer joint confirmed if conductor sizes differ across the joint
- Site hot-work permit status checked if heat-shrink’s torch step could be a constraint
- Installation instruction sheet for the exact kit part number reviewed before work starts
Why Buy Through eNarayan Elex
eNarayan Elex, Rasoolpura, Hyderabad (GST 36AACCE0195K1ZK) is an authorized distributor for the Raychem RPG cable accessories range across Telangana and Andhra Pradesh, alongside the wider cable accessories catalogue. For a jointing/termination requirement, share the cable’s voltage class, conductor size and the joint/termination type needed and the correct kit part number can be confirmed against current stock before dispatch.
FAQ
1. Can an 11 kV kit be used on a 1.1 kV LT cable, or vice versa?
No. Voltage-class kits are engineered for the electric-field stress at that specific voltage; using an MV/HT kit on LT cable or an LT kit on MV/HT cable does not meet the accessory’s design intent and is not a supported substitution.
2. What is the difference between a straight-through joint and a termination kit?
A straight-through joint connects two cable ends together mid-run and restores continuous insulation/screening across the splice. A termination kit lands a cable end onto switchgear, a transformer, a panel or another piece of equipment, and is supplied in separate indoor and outdoor variants.
3. How do I know what conductor size kit to order?
Read the mm² conductor size directly from the cable’s printed marking or the installation drawing, then match it to the kit’s stated size band – kits cover a size range, not one exact mm² figure.
4. Are outdoor termination kits different from indoor ones?
Yes. Outdoor terminations add UV- and tracking-resistant sheds/skirts designed for open-air exposure; an indoor kit is not built for that environment and should not be substituted outdoors.
5. What cable insulation types do these kits work with?
Raychem RPG’s heat-shrink LT and MV/HT kits are designed for XLPE-insulated power cable; PILC (paper-insulated lead-covered) cable uses separate accessory families – confirm the cable insulation type before ordering.
6. Can one joint kit be used to connect two different cable sizes?
Not with a standard same-size kit. A transition or reducer joint kit is required when conductor sizes differ on either side of the joint.
7. What is the largest conductor size these kits cover?
The LT/MV/HT heat-shrink range commonly covers up to around 630 mm², with select 11-33 kV joint and termination families extending further for larger conductors – confirm against the exact kit part number for your project.
8. What actually causes a heat-shrink joint to fail years after installation?
The two most common root causes are incomplete or off-centre stress-control positioning (which concentrates electrical field at an uncontrolled point) and moisture ingress through an outer seal that never reached full shrink recovery during installation. Both are installation-quality issues, not product defects, which is why following the kit’s specific instruction sheet exactly matters as much as buying the correct kit.
9. Is heat-shrink or cold-shrink jointing better?
Neither is universally “better” – heat-shrink (Raychem RPG’s core range) has the broader size-band tolerance and longer field track record for LT/MV/HT distribution cable in India; cold-shrink removes the torch/hot-work step, which matters specifically where a site’s hot-work permit rules restrict open flame. The right choice depends on site conditions, not a blanket preference.
10. Does jointing require a hot-work permit?
The heat-shrink method uses a controlled-heat torch to recover the components, so yes – standard hot-work permit procedures apply on most industrial/commercial sites. If a site prohibits hot work in the specific area (confined space, gas-adjacent, certain panel rooms), cold-shrink or push-on alternatives should be discussed instead.
11. Can a damaged cable be repaired with a straight-through joint instead of replacing the whole run?
Yes – this is one of the primary uses of a straight-through joint: splicing in a repair section after physical cable damage, provided the joint kit is correctly matched to the cable’s voltage class, conductor size and insulation type, and installed to the same standard as a new joint.
12. Does eNarayan stock Raychem RPG kits ready for same-day dispatch in Hyderabad?
Stock availability depends on the specific voltage class, joint/termination type and size band required – share your cable specification with eNarayan Elex, Rasoolpura, to confirm current stock before dispatch.
