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Contact Box (Spout Box) 12kV 630A-1250A
Contact box (spout box) is an epoxy resin insulating component engineered for 12kV medium voltage switchgear, rated for 630A to 1250A current carrying capacity. Manufactured using APG casting technology, this contact box features a smooth insulated inner cavity for high-voltage isolation, a busbar entry port for solid busbar connection, and anti-tracking skirts that increase surface creepage distance. The flanged square mounting base ensures secure installation into KYN28 switchgear, providing an isolating contact interface between VCB handcart and fixed cable or busbar conductors. This contact box is widely used in KYN28, HXGN, RMU, and GIS-type switchgear assemblies.
- Overview
- Applications
- Technical Data
- Services
- Quality Control
- Recommended Products
Epoxy Contact Box (Spout Box) - 12kV / 24kV, 630A to 1250A
Contact box, also called a spout box, is the fixed isolating contact interface between a withdrawable circuit breaker trolley and the panel's fixed busbar and cable conductors. It performs two jobs simultaneously: it houses the fixed contact that the trolley's tulip contact engages, and it provides the epoxy insulation barrier between that live contact and the earthed compartment wall. MOLDVOLT manufactures contact boxes for 12kV and 24kV withdrawable switchgear using APG casting.
THE COMPONENT THAT DEFINES WITHDRAWABLE SWITCHGEAR
Every time a breaker trolley is racked into service, its tulip contacts slide into Contact boxes and establish the main current path. Every time it is withdrawn, they separate. Contact box therefore carries full rated current continuously through a connection that is made and broken mechanically hundreds of times over the panel's life, while also holding off full system voltage to earth.
That dual duty is why contact box quality determines both the thermal and dielectric reliability of the whole panel. A contact box with degraded plating raises contact resistance and generates heat at exactly the point where heat is hardest to detect. A contact box with internal voids in the epoxy develops partial discharge and eventually punctures to earth. Neither failure gives warning.
SILVER-PLATED COPPER ALLOY CONTACTS
The fixed contact is copper alloy with 8-12 microns of silver plating, giving the lowest achievable contact resistance and resistance to oxidation. Plating thickness is measured by X-ray fluorescence and recorded per batch - under-plating is invisible on delivery and only reveals itself years later as a thermal fault. For coastal Gulf and West African installations where salt fog and sulphides attack silver surfaces, tin plating is available as an alternative.
APG CAST EPOXY BODY
The insulating body is cycloaliphatic epoxy, APG cast to produce a void-free matrix, and partial-discharge tested to below 10 pC at 1.1 times rated voltage. Cycloaliphatic resin is specified for its tracking and UV resistance across a -40 C to +105 C service range, covering both Gulf heat and CIS winter service.
INTEGRATED SHUTTER INTERFACE
Contact boxes are designed to work with the panel's automatic metal shutters, which close over the fixed contacts whenever the trolley is withdrawn. This is what ensures there is no exposed live metal inside the breaker compartment during maintenance.
SUPPLY
Available as OEM production to customer drawings and as direct-replacement spares for KYN28, HXGN and equivalent panels. Where the original part is obsolete, send a sample or drawing and we will produce an equivalent.
PRIMARY APPLICATIONS
- Busbar-side and cable-side isolating contacts in KYN28-12 and KYN28-24 withdrawable metal-clad switchgear - the primary application.
- VCB trolley isolating interface in withdrawable switchgear of all types.
- PT and metering trolley isolating contacts.
- Isolating contact interface in withdrawable LV motor control centres, using the appropriate LV rating.
- Replacement spares for aged withdrawable switchgear across the installed base.
- Panel builder and switchgear workshop production stock.
- Retrofit projects where a new breaker trolley is fitted to an existing panel and contact boxes have degraded.
WHY THIS IS A CRITICAL SPARE
Contact boxes degrade in ways that are invisible until failure. Repeated racking wears the plating; a misaligned trolley damages the contact; pollution and humidity attack the epoxy surface. The result is either a slow thermal rise that eventually causes a fault, or an insulation failure to earth. In both cases the panel is out of service until the box is replaced, and because it is behind the shutters it is not a part that can be improvised.
Given that limited spare parts availability is a leading barrier in Middle East and African electrical markets, contact boxes belong in the two-year spares list for any withdrawable switchgear fleet.
SELECTION GUIDANCE
Specify by rated voltage and BIL, rated current, contact geometry and dimensions matched to the trolley tulip contact, mounting interface and hole pattern, and plating type appropriate to the environment - silver for indoor clean service, tin for coastal and industrial atmospheres.
REGIONAL FIT
- Middle East: coastal salt fog and high ambient temperature. Tin plating and verified elevated-temperature performance are the relevant specifications.
- Africa: high replacement demand across an aged installed base of withdrawable switchgear, often with no OEM support remaining.
- Russia and CIS: low-temperature service to -40 C, requiring verified epoxy performance at temperature.
- Eastern Europe: standard IEC service in temperate switchrooms.
NOT SUITABLE FOR
Fixed-type switchgear with bolted busbar connections, which has no isolating contact interface. Current ratings above the selected type. Outdoor unprotected installation.
TECHNICAL DATA - Epoxy Contact Box (Spout Box)
Compliance: IEC 62271-200 (as part of the switchgear assembly), IEC 60168, IEC 62217
Electrical Ratings
| Model | Rated Voltage | Rated Current | BIL | Power-Frequency Withstand (1 min) |
| 12 kV / 630 A | 12 kV | 630 A | 75 kV peak | 42 kV |
| 12 kV / 1250 A | 12 kV | 1250 A | 75 kV peak | 42 kV |
| 12 kV / 1600 A | 12 kV | 1600 A | 75 kV peak | 42 kV |
| 24 kV / 630 A | 24 kV | 630 A | 125 kV peak | 50 kV |
| 24 kV / 1250 A | 24 kV | 1250 A | 125 kV peak | 50 kV |
| Parameter | Specification |
| Partial Discharge | < 10 pC at 1.1 × Uₙ |
| Short-Time Withstand Current | 25 kA / 31.5 kA for 4 s (matched to panel rating) |
Contact
| Parameter | Specification |
| Contact Material | Copper alloy (CuCrZr or equivalent) |
| Surface Treatment | Silver plated, 8 – 12 µm standard; tin plating available for coastal & industrial service |
| Plating Verification | X-ray fluorescence measurement, recorded per batch |
| Contact Resistance | Measured and recorded on every piece |
| Temperature Rise | Within 70 K limit per IEC 62271-1 at rated current |
Body
| Parameter | Specification |
| Material | Cycloaliphatic epoxy resin, APG cast |
| Colour | RAL 7035 light grey (standard) |
| Inserts | Brass or steel threaded inserts, cast in |
| Mounting | Flange with bolt pattern to customer specification |
| Shutter Interface | Designed for panel automatic shutter engagement |
Creepage
| Parameter | Specification |
| Standard Creepage | ≥ 16 mm/kV |
| Extended Creepage | 20 mm/kV / 25 mm/kV (medium & heavy pollution) |
Service Conditions
| Parameter | Specification |
| Operating Temperature | −40 °C to +105 °C |
| Altitude | Up to 1000 m standard; up to 2000 m on request |
| Humidity | Suitable for tropical & high-humidity service |
| Flame Retardancy | UL94 V-0 grade available |
Testing — Every Piece / Every Batch
| Test Item | Scope |
| Partial Discharge Test | Every piece |
| Power-Frequency Withstand Voltage Test | Every piece |
| Contact Resistance Measurement | Every piece |
| Plating Thickness Verification (XRF) | Every batch |
| Dimensional Inspection (critical fit dimensions 100% checked) | Every piece |
| Visual Inspection (cracks, voids, plating defects) | Every piece |
| Temperature Rise Verification | Type samples |
| Salt-Spray Testing | Coastal-service parts |
OPTIONS
Tin plating for coastal and industrial atmospheres | extended creepage | custom contact geometry and mounting to customer drawing | customer part numbering and packaging | flame-retardant UL94 V-0 formulation | low-temperature verified formulation for GOST 15150 service | reverse engineering from sample for obsolete parts
SPECIFICATION AND SOURCING
- Send a drawing, a sample or a photograph with the existing part number and we will identify the equivalent and confirm fit before you commit to an order.
- Reverse engineering from a physical sample where the original part is obsolete or the OEM no longer supplies it - common for aged KYN28, HXGN and imported panels still in service across Africa, CIS and the Middle East.
- OEM and private-label production to your drawings, with your part numbering and packaging.
- Material and plating selected for the destination environment: silver plating for lowest contact resistance indoors, tin plating for coastal and industrial atmospheres where salt fog and sulphides attack silver.
WHY THIS MATTERS COMMERCIALLY
Limited local technical expertise and difficult spare parts supply are consistently identified as the main barriers in Middle East and African electrical markets. A panel is out of service for as long as it takes the part to arrive. We hold consumable items in stock and quote fleet spares lists against your installed base so the part is on the shelf before it is needed.
QUANTITY AND LEAD TIME
- Stock items dispatched from inventory; typical production lead time 15-25 days for standard specifications.
- Low minimum order quantities on standard parts - we supply single-piece emergency replacements as well as bulk production volumes.
- Air freight for breakdown situations, sea freight consolidation for planned restocking.
TESTING AND DOCUMENTATION
- Routine testing per applicable IEC standard with results supplied per batch.
- Material certificates, plating thickness reports and dimensional inspection records available on request.
- Certification support for SONCAP, KEBS PVoC, SABER and GOST R submissions where the component ships as a standalone consignment.
AFTER-SALES
- Technical response within 24 hours; application engineering support for fit, assembly torque and maintenance intervals.
- Warranty against manufacturing and material defects: 12 months from delivery.
- Framework and call-off agreements available for panel builders, utilities and switchgear service workshops.
MATERIAL CONTROL
- Copper verified as T2 grade electrolytic copper or specified copper-silver alloy, with mill certificates retained per batch.
- Epoxy resin verified as cycloaliphatic grade with documented gel time, viscosity and filler ratio; general-purpose bisphenol resin is not accepted for outdoor or high-humidity service because of its poorer tracking and UV resistance.
- Plating thickness measured by X-ray fluorescence and recorded per batch - typically 8-12 microns of silver on contact surfaces. Under-plating is invisible on delivery and only shows up years later as a thermal fault, so this is measured rather than assumed.
PROCESS CONTROL
- APG (Automatic Pressure Gelation) casting under controlled mould temperature, injection pressure and gel time, producing a void-free matrix. Voids initiate partial discharge, and partial discharge is what eventually punctures an insulator in service.
- Vacuum degassing of resin before injection to eliminate entrapped air.
- Controlled post-cure cycle to relieve internal stress and stabilise dimensions.
- Contact finger spring force calibrated and verified against specification, ensuring uniform current sharing across all fingers.
ROUTINE TESTING - EVERY PIECE OR EVERY BATCH
- Partial discharge test on insulation components, typically below 10 pC at 1.1 times rated voltage.
- Power-frequency withstand voltage test.
- Contact resistance measurement on current-carrying parts.
- Dimensional inspection against drawing, with critical fit dimensions 100% checked.
- Visual inspection for cracks, voids, plating defects and surface finish.
- Mechanical load testing on insulators against rated cantilever strength.
TYPE TESTING
- Insulators verified to IEC 60168 and IEC 62217; contacts and conductive parts verified for temperature rise within the 70K limit of IEC 62271-1 at rated current.
- Thermal cycling and, for parts destined for coastal service, salt-spray corrosion testing.
TRACEABILITY AND SYSTEM
- ISO 9001 quality management system.
- Batch numbering linking finished parts back to raw material certificate and process records.
- Certificates of conformity, material certificates and test reports issued with each shipment.
- Retained samples held per production batch for future reference in the event of a field query.
