Universal 2-USO 2 flameproof boxes







Uniwersalne skrzynki ognioszczelne typu 2-USO 2

By combining two type boxes USO 2-**** a flameproof enclosure of the type is created by means of the universal connector 2-USO 2-6402-R, which enables the connection of a cable with a voltage of 3.6 / 6 kV with 6 working cores with two cables or with 3.6 / 6 kV cables with 3 working cores The use of an additional universal connector creates a passage box. The resulting structure is marked with 2-USO 2-6402-P.

Universal flameproof boxes type USO 2 – **** They are suitable for safe use in underground mines in workings classified as “a”, “b” or “c” of methane explosion hazard and “A” or “B” class of coal dust explosion hazard.Universal flameproof boxes type USO 2 – **** are intended for connecting shielded mining power cables made of thermoplastics and mining tire cables, in insulation, sheath and tire made of electro-electricians with rated voltages not exceeding 3.6 / 6 kV in all workings of non-methane and methane mining plants.

Flameproof box type 2-USO 2 – **** – * with a universal connector:

  • 2-USO 2-6402-R – box with an insulation level of 6000 V + 20%, with 400 A current terminals, 2 cable inlet sockets, branched
  • 2-USO 2-6402-P – box with an insulation level of 6000 V + 20%, with 400 A current terminals, 2 cable inlet sockets, cruising

Flameproof boxes type 2-USO 2 – **** – * together with the universal connector are marked with the type: 2-USO 2 – **** – * where:

  • 2-USO 2 – means a flameproof box with a universal connector,
  • first * – rated operating voltage: 6 – 6000V (max 7200 V),
  • second and third * * – maximum current: 40 – max 400 A,
  • fourth * – number of cable inlet sockets: 2 – two cable inlet sockets,
  • fifth * – box type:
    R – branched,
    P – cruising.

Universal flameproof boxes type USO 2 – **** have the approval of the State Mining Authority and the ATEX certificate: OBAC 09ATEX266X z from 30.07.2012.

Universal flameproof boxes type USO 2 – **** can be used in underground mine workings only for connecting cables and shielded wires.


Rated data

Box type2-USO 2-6402-R
2-USO 2-6402-P
Nominal voltage Un
Nominal currentIn
6000 V+20%; max 7200V
400 A
Rated voltage of auxiliary and control lines25 V AC; 60 V DC
Short circuit current Iz
Short circuit time tz
10 kA
0.1 s
Number of inlets1+2 inlets for the manifold
1 + 1 entries for straight through
Type of inlets,
type of drain plug
WKp-1, WKp-2, WKp-3, WKp-4, Z-WKp
I M2 Ex d I Mb
II 2G Ex d IIC Gb
Drain reduction typeR-WMg-*
I M2 Ex d I
Type of cable entries WMg
I M2 Ex d I Mb
II 2G Ex d IIIC Db IP65
Possible combinations:
– power veins
– control wires
– grounding conductors
– force veins screens
– general screens
max 1 wires/phase, 150 mm2
max 6 wires, max 4 mm2
max 70 mm2
into the housing
into the housing
Level of security IPIP-54
Working temperaturefrom -10oC to +40oC
Work locationhorizontal
Total weightabout 110 ÷ 130 kg

– Weight given without cable entries,
– Each gully seat can be plugged with an approved Z-WKp gully plug or R-WMg reducer


The universal connector as a flameproof casing is made of 8 and 12mm thick sheets welded together with a tight weld. The sheet to which they are screwed USO 2 inlets and flat bars forming a flameproof joint with the cover (after its installation) are 12mm thick. Each threaded hole has a threaded sleeve welded from the inside by a tight weld. All tapped holes have a medium-precision fit. Universal connector cover made of 12mm thick sheet metal, it also has protective sleeves welded on for bolts.
It is tightly welded to the front plate of the universal joint socket WKp. The rear plate is milled over the entire surface to a minimum thickness of 10 mm, the same is the flame-proof surface and the cover of the universal connector.

A fastener for a 6-wire cable is welded to the bottom inside the universal connector. In  the middle of the universal connector, a grounding clamp is attached to ground the screen of the general conductor. On the outside of the universal connector there is one earthing terminal for earthing the flameproof box type 2-USO 2 – **** -* together with the universal connector.

The universal connector is closed with a flameproof cover with a flameproof flange surface. The cover is screwed with M10x35 allen screws in class 12.9.

Flameproof box type 2-USO 2 – **** – * with universal connector  in order to protect against corrosion, it is covered externally with one layer of Gruntokor C phthalate primer, and then with one layer of Nitromal cellulose enamel (red). The universal connector inside is painted with Nitromal cellulose enamel (white). Paint layer thickness 0.2 mm.

The universal connector consists of two inlets USO 2, made with fight. The shaft is pre-treated and then a sheet of metal is welded to it. Between the sheet of the universal connector and the groove USO 2. After screwing in four M10x35 allen screws in class 12.9, a flameproof flange joint is created and groove USO 2 with socket WKp of box USO 2-**** forms a flameproof cylindrical joint.

Flameproof box type2-USO 2-***-* together with the universal connector, it is a mechanical connection of two USO 2 – **** boxes, which allows you to connect a 6-core cable from the supply side and divide it into two cables / wires 3 – wires that are connected to the receivers. The 6-wire cable is attached at a universal connector with a line of groove Wkp and with a mounting bracket. In the center of the universal connector, the split cores of the 6-wire cable are distributed directly into the appropriate openings of USO 2 – **** boxes, and then connected to insulators.

Flameproof boxes type 2-USO 2 – *** – * together with a universal connector, the main purpose of which is to connect power cables and mining cables, intended to work in the underground of mining plants with the same wire cross-sections. It is also allowed to connect sections of cables and wires with different cross-sections, but the maximum load for a given 3-track system cannot be higher than the allowable load for a cable or wire section with a smaller cross-section and not greater than the allowable load for a given type of junction box used.

Various combinations of connected elements are allowed, i.e .:

  • 6-wire cable —— 3-wire cable + 3-wire cable,
  • 6-wire cable —— 3-wire cord + 3-wire cable,
  • 6-wire cable —— 3-wire cord + 3-wire cord.


Flameproof boxes type 2-USO 2 – **** – * with a universal connector having a test certificate WE: OBAC 13 ATEX 0291X from 22.11.2013r. issued by the Center for Testing, Attestation and Certification OBAC Sp. z o. o. in Gliwice. 
The basic requirements of safety and health protection were implemented by meeting the requirements of the following standards:

  • PN-EN 60079-0:2009
  • PN-EN 60079-1:2010

Flameproof boxes type 2-USO 2 – **** – * with a universal connector are marked with:
OBAC 13 ATEX 0291X
I M2 Ex d I Mb



By the decision of the President of WUG, universal flameproof boxes type 2-USO 2 together with a universal connector, are approved for use in underground mining plants.

  • 2-USO 2 – GX – 95/14 pismo: L.dz. 22484/07/2014/RS/KR/GEM.4740.46.2014



Download the catalog card:

Universal type flameproof box 2-USO 2

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