The order an MV joint goes together, and where the earth path goes
Ten stages read off the bills of material, with the screen and armour connections pulled out as a stage of their own.
This is our reconstruction. The manual in the box beats it
No jointing procedure is published anywhere in the manufacturer's range. Every kit ships an Installation Instruction Manual, 1 No., counted as a line item, and that sheet is not on the web. What follows is Kit Sheet's reading of the GXS/1236, GXSS, GPS and GTJ bills of material together with the numbered cross-sections printed beside them. It gives you the order and the reason for the order. It gives you no cut-back dimension, no shrink temperature and no crimp die, because none of those exists in any published source. Open the manual before the knife. Where the two disagree, the manual is right and this page is wrong.
The rule that comes before the first cut
Setting-out first. Both ends past each other, cleaned, supported and reachable, before a single strand is stripped. A joint made kneeling in the wrong place is a joint made twice.
Then the sleeving. A GXS/1236 box holds three stress control sleeves, three or six red insulating tubes, three dual-wall screened tubes and three outer jacketing sleeves — one centre plus two sides. Each of those is a closed tube. None will pass a crimped ferrule and none can be split and rejoined.
So they are threaded on first and parked well back, in the order they will be pulled forward and facing the way they will be pulled. Marking that order on the sheath costs a strip of the PVC adhesive tape already in the box.
The wraparound joint case is the only exception. Item 11 on the GXS sheet closes around a finished body, so it waits until stage 9. So does the GI mesh application the same sheet offers in its place.
Ten stages, in order
Written for a three-core extruded-dielectric straight-through joint on the GXS/1236 manifest. Where a paper or transition kit diverges, it is said in the stage.
1 · Set out, then count the box
Support both ends and check the carton code against conductor area first: GXS-11 to GXS-15 at 12 kV, GXS-21 to GXS-25 at 15–24 kV, GXS-31 to GXS-34 at 36 kV. Then tick the manifest off item by item. A short box ends the shift rather than delaying it.
2 · Park every closed tube on the cable
Stress control sleeves, red insulating tubes, dual-wall screened tubes, the centre jacketing sleeve and both side sleeves. Note which end each one came off and which way round it sits. This is the stage that has no second attempt.
3 · Cut back the layers
Outer sheath, armour, inner sheath, metallic screen, then the semi-conducting core screen and the XLPE. Those six are callouts 14 to 19 on the GXS sheet and not one of them ships in the box — they are the cable, drawn so the kit items have something to be numbered against. Take every dimension off the instruction manual. No jointer's memory holds three voltage classes.
4 · Take the core screen off, then stop touching the insulation
The box supplies a nylon string, named on the sheet for cutting XLPE insulation, and three lengths of aloxite emery tape. No sheet in the range states how the semi-conducting screen itself comes away; that is manual territory. Finish with the cleaning tissue, six pieces, and the mopping cloth, working off the insulation and never back onto it. From here the XLPE surface is out of bounds to a glove, a rag and a finger.
5 · Crimp the inline connector
Three ferrules in a three-core kit, one in a GXSS. GPS/1112 is the sheet that spells the material choice out — inline connector, crimping type, ferrule Cu/Al — so it follows the conductor, not the van. A GTJ transition kit carries a barrier-type connector instead, three per kit, alongside three oil barrier sleeves. Nothing after this stage can be undone by heat.
6 · Mastic at the ferrule, mastic at the screen edge
A GXS/1236 carries stress control mastic at 6 or 9 pieces by voltage class, a grey or yellow stress control mastic at 6 strips, and red mastic again at 6 or 9. Between them they fill the step the crimp leaves and the void at the screen cut-back. The black stress control sleeve, three per kit, then goes over the graded edge.
7 · Rebuild insulation, then screen, in that order
Red insulating tubing: three pieces at 12 kV, six at 24 and 36 kV, straight off the quantity column. Then the dual-wall screened tubing, red and black in a single wall, three per kit. Insulation inside and screen outside is not a preference. Reversed, the joint has a conducting layer where its insulation should be.
8 · Carry the screen and the armour across
Copper woven flexible mesh tape, three rolls, laid onto the cable's copper foil screen at both ends. Each is fixed with a solder tack, or with the roll spring the sheet prints as the alternative at three pieces. The tinned copper braid — one per kit, labelled main earthing — then bridges the two ends. Armour is a separate connection with its own hardware: four worm drive clips in a GXS, two jubilee clamps in a GTJ/2436, six in a GTJ/1112. On a lead sheath the connection is plumbed, using the plumbing metal counted one set per GTJ kit.
9 · Close the mechanical protection
One wraparound metallic joint case per kit, over the finished body. The GXS sheet prints a substitution against it in as many words: item 11 may be replaced with a GI mesh application. That is a swap for the case. It swaps nothing in stage 8.
10 · Seal the outside
Three outer jacketing sleeves — centre first, then the two sides overlapping onto the cable sheath — with mastic sealing tape under the adhesive lining at each end. The GXLT type-test schedule immerses a finished straight-through joint for a 63-cycle heating test, five hours heating and three hours cooling at 95 °C conductor temperature, with no breakdown and no flashover allowed. That is what the last sleeve is asked to survive.
Where each series picks the earth path up
| Series | Screen connection | Armour or lead sheath | Main earth across the joint |
|---|---|---|---|
| GXLT/GPLT, 1.1–3.3 kV | No screen on the cable | Armour continuity connection with worm drive clamps, callouts 4 and 5; the paper drawing shows an armour/lead sheath continuity system and a plumb | Not separately numbered on either drawing |
| GXS/1236, 12–36 kV | Copper woven flexible mesh tape, 3 rolls, fixed with solder tack or roll spring (1 set / 3 Nos.) | Worm drive clips, 4 Nos. | Tinned copper braid, 1 No., printed main earthing |
| GXSS/1236, single core | Copper woven flexible mesh tape 1 roll and GI mesh 1 roll, with spring clamp or solder flux (2 Nos. / 1 set) | Not separately listed | No earth braid appears on this sheet |
| GPS/1112, 11 kV PILC | Copper woven flexible mesh tape, with GI wire mesh at item 2 | Item 3 is one line: copper braid, plumbing metal, flux and copper binding wire | Inside item 3, not counted on its own |
| GPS/2436, 24–36 kV PILC | Copper mesh tape with a constant force spring clamp | Worm drive clamp, and an earthing plumb at item 19 | Earth lead, item 15 |
| GTJ/1112, 12 kV | Tinned copper mesh tape, 3 Nos., with a constant force spring clamp or solder and flux | Jubilee clamps, 6 Nos., plus plumbing metal, 1 set | Tinned copper earth braid, 1 No. |
| GTJ/2436, 24–36 kV | Tinned copper mesh tape, 3 Nos., same spring-or-solder choice | Jubilee clamps, 2 Nos., plus plumbing metal, 1 set | Tinned copper earth braid, 1 No. |
Item names and counts as printed on the manufacturer's own joint sheets, normalised for spelling only. Two cells read not listed because the sheet does not carry that line — not because the connection is not made. The single-core GXSS/1236 sheet is the one to raise: it is the only joint sheet in the range with no earth braid on it.
Six ways the earth path is lost after it was made
Not one of these is visible once the joint case is closed. All of them present the same way later — an unearthed screen or a broken armour path, the first time the circuit sees a fault.
- The spring landed on the jacket. A roll spring or constant force clamp closed over the outer sheath instead of onto the metal it was meant to grip. From a metre away in a trench the two look identical.
- A cold solder tack. The sheet offers solder or a spring as alternatives, so the solder is not incidental — it is one of the two published ways the connection is made. A tack that wets one side only holds mechanically and conducts badly.
- A clamp on the wrong layer. Worm drive clips belong on the armour wires. Tightened over the inner sheath they still bite, still look correct and connect nothing.
- Plumbing skipped on a lead sheath. The plumb is the connection there. GTJ sheets count plumbing metal one set per kit and GPS/2436 names the finished thing an earthing plumb. No clamp is printed anywhere as a substitute for it.
- GI mesh mistaken for an earth conductor. The published substitution is GI mesh in place of the joint case, and the case is mechanical protection. Nothing about the braid, the mesh tape or the springs changes when that swap is taken.
- The braid made off at one end. One main earthing braid per kit, and it has two ends to connect. Half a braid still reads through to earth from the near side.
The bonding scheme is not in the box
Nothing in the joint literature indexed here addresses screen bonding. No link box, no sheath voltage limiter and no cross-bonded arrangement appears on any joint sheet in the range, at any voltage class.
That is not an omission. A joint restores the screen through the joint; where that screen is earthed was settled in the cable system design long before a kit code was chosen. Single-point bonded circuits still need continuity across every straight-through joint on the run, because the screen has to reach its one earthing point.
The question bites hardest on single-core cable, which is where GXSS/1236 lives. A screen earthed at both ends of a single-core circuit forms a closed loop around a conductor, and whether the design accepts that is a design answer. It is not on the kit sheet.
If the joint sits inside a bonding scheme with a link box or a limiter, say so in the enquiry. A body that has to bring a screen lead out of it is not the joint these cross-sections draw.
Two mistakes you cannot fix from where you are standing
A sleeve left off the cable. Once the ferrule is made off, the only route to getting a closed tube past it is to cut the joint out and open a fresh kit. The sheets are explicit that a kit is complete for one joint, so there is no second ferrule waiting in the carton.
Semi-con left on the insulation. A smear of core screen on the XLPE is a conducting path lying underneath everything shrunk over it afterwards. It survives torchlight, it survives handover, and it is never visible again.
Neither shows at the end of the shift. The tests built to find them — the 63-cycle heating cycle in water, the impact test for straight-through joints, the thermal short-circuit test — are run on laboratory samples for a type approval, not on the joint going into your trench.
No source for these
Cut-back and setting-out dimensions. The cross-sections in the joints catalogue are unscaled and undimensioned; the figures exist only in the instruction manual. Shrink temperature, flame type, torch distance. Nothing published anywhere in the range. Crimp die and tonnage. No tool of any description is named on any joint sheet. Torque for a worm drive clip or a jubilee clamp. Nothing. A site acceptance value for continuity or insulation resistance. The published 1 min. 500 V DC, >10³ Ω figure is a type test on a sample, taken before and after an impact test, and it is not an acceptance criterion for a joint in the ground. How long a cleaned surface may stand before it is shrunk over. Nothing. Kit Sheet holds no stock and quotes nothing, so all six are questions for the manufacturer.
Asked on site
Which jointing tools does the kit not include?
Does the sequence change on a 1.1 kV joint?
Can the insulation be cleaned with a solvent from the van?
How is the earth path verified before the joint is closed?
Is a transition joint built in the same order?
Where the rest of this sits
- Every part in a joint kit, named and countedThe full GTJ/2436 manifest, the GXLT callout key, and which numbered items are the cable rather than the kit.
- The sleeves parked on the cable at stage 2Stress control, red insulating, dual-wall screened, oil barrier — and how the counts move with voltage class.
- Kit codes against conductor areaGXLT, GXS, GXSS, GPS and GTJ charts. Read before stage 1, not after.
- The GXS manifest this sequence was read offThirteen kit components, eight installation aids, six cable components the kit has to match.
- The single-core kit with no braid on its sheetGXSS-11 to GXSS-35, and the earth-path line the sheet does not print.
- Six ways a joint failsRead backwards from the failure to the stage on this page where it was made.