Indoor or outdoor termination: what actually changes in the kit

Tail length is the figure that has to reach the drawing

Tail length sets how far the cores run from the breakout to the lug, so it is the number that must agree with the switchgear general arrangement before anything is ordered. The ladder is the same on all three three-core families and on the single-core one: 600, 800 and 900 mm outdoor at 12, 24 and 36 kV, against 450, 550 and 700 mm indoor. The indoor tail is shorter by 150 mm at 12 kV, 250 mm at 24 kV and 200 mm at 36 kV.

Special tail lengths are published as available on request on the GXO/E series, which is the route when the gland plate to bushing dimension does not suit the standard figure — see the manufacturer's GXO/E-1524 page for that kit's full contents list.

A rain shed is a creepage component, not an outdoor badge

The shed supplied in these kits is INSULSHED, cross-linked polyolefin with non-tracking behaviour, internally coated with water-resistant mastic and described by the manufacturer as suitable for indoor and outdoor applications alike. Its figures do not change with where it is fitted: no tracking, erosion or flame failure up to 3.25 kV for 20 minutes [ASTM D2303], dielectric strength 15 kV/mm minimum [ASTM D149], volume resistivity 1 × 10¹⁴ ohm.cm minimum [ASTM D257], shrink temperature 125°C and a continuous limit published as −40°C to +100°C on the datasheet and +110°C on the product page [IEC 216]. Ten sizes are charted, GRS 130-1 to GRS 130-6 with four N and S variants between them, published on the creepage extension skirt page.

That matters for the case the code letter cannot express. A termination inside a coastal switchroom, a cement or fertiliser plant, or a naturally ventilated substation beside a haul road collects salt, dust and conductive deposit across the same surface an outdoor one does, minus the rain that periodically washes it off. A sealed, air-conditioned panel collects almost none. Both are 'indoor'.

Where the switchroom is dirty, the creepage extension can be specified on its own rather than by changing the kit — sizes, and the tri-core GRST-1 to GRST-3 variant that fits over three cores at once, are set out under rain sheds. That judgement is the specifier's to make and to record.

The call is made at requisition, not on site

GXO-23 and GXE-23 are different part numbers holding different contents. A crew that opens an indoor box at an outdoor termination has no rain sheds and 150 mm less tail than the drawing assumes, and neither shortfall is recoverable with what is in the van. So indoor or outdoor belongs in the cable schedule next to insulation type, core count, mm² and Umax, before the requisition leaves the office.

For a first cut by construction rather than by voltage, XLPE and EPR kits, PILC kits and LV kits at 1.1 and 3.3 kV each list their own code pairs, and what is in the box itemises the components both variants share.