Placement · burial · duct · pit · immersion

Joints that live in water

The cable picks the series. The position picks how hard that series is being asked to work.

Design from the wettest day, not the day of the job

A pit gets pumped on the morning of the work and never again. A duct runs to a low point and keeps whatever collects there. Ground water moves with the season and nobody logs it. So the working assumption for anything buried is standing water for the whole service life.

That does not change which kit you order. Insulation type, core count and voltage class still choose the series on the kit selector, and conductor area chooses the code inside it. The position changes the mechanical item you accept, the care taken over the two ends of the outer seal, and one line in the enquiry that most enquiries leave out.

Nothing in the box changes with depth. The whole difference between a dry joint and a wet one is made in the specification and on site.

Four positions, and what each one asks of the joint

Ordered by how wet they get rather than how deep they go.

Direct burial

Bedded in fill and covered over. The loading is mechanical, permanent and never re-tightened, so the mechanical item carries the position — a wraparound joint case, or the galvanised mesh the catalogue prints in its place. Heat leaves through the soil, which makes the ground part of the joint's rating and a trench that dries out a worse place than the same trench in monsoon.

Duct run, jointed in a chamber

The joint sits in a bay; the duct is the route water uses to reach it. A circuit in duct sheds heat less readily than the same circuit laid direct, so the conductor sits hotter for the same current and the joint cycles harder. That matters more than the standing water, because the qualification the kit carries is a heating cycle test rather than a soak.

Draw pit or manhole

The most accessible position on a distribution run and reliably the wettest. It takes surface water and silt, gets pumped for the work and refills behind you. It is also the position the manufacturer's own qualification most nearly describes: a straight-through joint energised and load-cycled with water around it.

Permanently submerged

Under water by design rather than by flooding — a crossing, a sump, a shaft that stays full. The joint never dries, never gets looked at, and head acts on every seam without a break. Here the manufacturer lists a distinct series rather than a variant, and publishes one line about it.

The chain that closes the joint is not the same in every box

In principle every joint here finishes the same way: mastic and an adhesive lining onto original cable jacket, a jacketing sleeve over that, a mechanical item over everything. In practice the bill of material differs by series, and the differences are the ones a wet position cares about — how many sleeves close the ends, whether a rigid case is supplied at all, and whether the mesh replaces that case or is the only thing on the sheet.

One wording difference is worth carrying into the enquiry. The catalogue prints adhesive lined against the GPS/1112 outer jacketing and against the side sleeves in GPS/2436 and GTJ/2436. It does not print it against the GXS or GXSS jacketing sleeve. Probably a difference in how two pages were written rather than two different parts — but under permanent head it deserves a question.

What closes the joint against water, by series

Series	Outer jacketing	End sleeves	Mechanical item
GXLT / GPLT · 1.1–3.3 kV	Outer jacketing sleeves, item 11, no quantity printed	Not listed	Wraparound joint case, item 7 — galvanised mesh offered in its place
GXS/1236 · 3-core · 12–36 kV	Centre sleeve, part of item 12	2 side sleeves; item 12 is 3 pieces in total	Wraparound metallic joint case, item 11 — GI mesh may replace it
GXSS/1236 · single core · 12–36 kV	Outer jacketing sleeve, item 12, 1 No.	Not listed	GI mesh, 1 roll, item 8 — no case on the sheet
GPS/1112 · 11 kV PILC	Adhesive-lined outer jacketing, item 1	Not listed	GI wire mesh, item 2 — no case on the sheet
GPS/2436 · 24–36 kV PILC	Outer jacketing sleeve, item 18	Adhesive-lined side sleeve, item 12	Metallic protection cage, item 11
GTJ/2436 · transition · 24–36 kV	Outer jacketing tubing, centre, item 19, 1 No.	2 adhesive-lined side sleeves, item 13	Metallic protection case, item 12 — GI mesh tape offered in its place

Items and quantities as printed in each series' bill of material, Issue 2 catalogue, September 2018. Not listed means the line is absent from that sheet.

GXLTS — named, and nothing more

GXLTS appears once in the manufacturer's joints index, carrying one description: heat-shrinkable straight-through joints for submersible cable. No source for the voltage classes it covers, the constructions it accepts, a kit code, a conductor range, or any test under head. It has no ordering chart in the Issue 2 catalogue, so the series can be asked for by name and cannot be written into a schedule. Where a run is submerged by design, put that first in the enquiry and let the manufacturer's joints index answer with a series and its evidence.

Where the IP68 question stops being useful

IP68 is the wrong thing to ask a joint for, and not because the sealing is weaker than the rating sounds. Under IEC 60529 the second digit 8 means continuous immersion under conditions specified by the manufacturer — depth and duration arrive with the claim, not with the number. It also describes an enclosure at rest. A joint in a pit is not at rest: it heats and cools with the load, it shifts when the ground shifts, and the bond that has to hold is made onto a cable jacket doing the same.

The catalogue answers the harder version instead. Straight-through joints are qualified by a heating cycle test in water — 63 cycles of eight hours, five heating and three cooling, energised at 16, 30 or 45 kV AC by class — and that sequence, declared against IEC 60502-4 and CENELEC HD 629.1, ends with an examination looking specifically for a moisture path across the primary seal. The 1.1 and 3.3 kV series is tested the same way at lower figures, on the manufacturer's GXLT/GPLT joint page and in full on the LV kit page.

Not published anywhere in this record

A depth, head or pressure figure against any joint kit in the range, the submersible series included. A backfill grade, bedding specification or burial depth — those belong to the utility's standard for the run, not to the kit. A derating factor for a joint in duct. A rule for choosing the wraparound case over the mesh: the sheets print them as alternatives and stop. And the usual four — price, lead time, shelf life and stock. No source here for any of it, and none will be invented.

Asked from the trench

Do I need a special kit for a joint that will end up under water?

For a pit, a duct or direct burial, no. The standard straight-through series are qualified with the joint in water, so the position changes what you say in the enquiry rather than which series comes back. For cable submerged by design, GXLTS is listed separately and carries one line of published detail — so name the condition, not the code.

Can a joint be made in a flooded pit?

No. Every kit here is heat-shrinkable, and the shrinking stages want a surface the adhesive can wet. The boxes ship cleaning tissue, mopping cloth, aloxite emery tape and silicone grease, which is a fair indication of the condition the sheets expect. Pump it, tent it, dry the sheath well past the cut-back, keep it dry until the last sleeve is down. The joint lives in water afterwards. It cannot be made in it.

Wraparound case or GI mesh in a wet trench?

The sheets treat them as alternatives, not as a better and a worse. GXLT, GXS and GTJ each print the mesh as a substitution for the case; GXSS and GPS/1112 list a mesh and no case at all, while GPS/2436 lists a cage. No source for a selection rule between them, so it stays a question for the manufacturer, asked with the position stated.

Does the earth path need anything different underground?

Nothing extra is supplied for it. Continuity arrives as the same mesh tape, springs, clips, braid and — on paper cable — plumbing metal every kit already carries. What depth changes is that a fault in that path will not be found by looking. Stage order is on the stage list; the parts are counted on the contents manifest.