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Thursday, 2 August 2012

SMC JUNCTION BOX


 SMC JUNCTION BOXES 
                      
Electrical junction boxes are devices that contain the wiring junctions or intersections that allow the wiring in the home or public building to interface with the main power supply provided by a local utility. The presence of the junction box is generally regarded as both practical and more aesthetically pleasing than a bunch of exposed electrical wires.

For many people, the main purpose of a junction box is to conceal the electrical junctions from sight. Usually constructed with the use of metal or hard plastic, the general appearance of a junction box is either a square or rectangular design. A door on the front of the box allows access to the interior. The door may be recessed in the front of the junction box, or the entire facing may swing upward or downward to allow access to the junctions within the device. In many homes, the junction box proper is recessed into a wall, with only the front panel open to view. This makes it very easy to hand a piece of art over the junction box and hide it completely from view.

While it is true that the junction box presents a neater means of concealing electrical junctions, the real value of the box is providing a degree of protection for the wiring interface at various junction points. It provides facility to connect two or more different size of cable.

Limitation:
·         The junction box can also help contain sparks in the event that one of the junctions overloads for some reason, and thus limit the amount of damage that is caused.
·         The typical junction box today usually includes a safety switch that allows the connections made within the box to be shut down in an emergency.
·         Cost is additional.
·         It increases resistance of circuit path.

The life of a typical electrical junction box can be measured in decades. Occasionally, upgrades to the wiring within the building will dictate the installation of a larger junction box to accommodate additional electrical junctions or larger electrical cables. However, if the original wiring remains in good condition and there is no added burden placed on the overall electrical system within the building, the junction box does not usually have to be replaced.

 While some junction boxes are indoors, like the kind that can be inserted  into a wall and covered by artwork, there are also outdoor junction boxes. In this case, I would recommend a weatherproof junction box. Outdoors, the electrical wiring should be protected from the elements.
Cut out: Knockouts are partially cut-out sections, usually circular in shape, which can be forced out easily to create a hole or opening. Typically, knockouts come in standard sizes and advisable to use in bottom side to avoid water ingress.

Mounting: Enclosures are wall-mounted, pole mounted, over flush and under flush type.

Protection: Enclosures provide protection against dust i.e. IP55, 65 etc
Material:
Mild steel
Stainless steel
Galvanised steel
Polycarbonate

NEMA enclosures are designed for indoor or outdoor use. They protect personnel against incidental contact with the enclosed equipment and protect the enclosed equipment from falling dirt, rain, sleet, snow, and windblown dust. Type 3 NEMA enclosures are undamaged by the external formation of ice on enclosure.
Type of Junction Box
1.      Electrical Junction Boxes
2.      Wiring Junction Boxes
3.      Electric Junction Boxes
4.      Plastic Junction Boxes
5.      Cable Junction Boxes
6.      Plastic Electrical Junction Boxes
7.      Weather proof junction boxes
8.      Flameproof junction boxes

Weather proof junction boxes shall be as per IS-2147
Flameproof it shall be as per IS-2148 suitable for the area classification specified.
 Number of entries and locations shall be on e or more as per our requirement.
Weather proof junction boxes shall have doors which shall be hinged type and these shall be fixed by plated countersunk screws.
Installation: Outdoor, open air, indoor

SITE CONDITIONS
Ambient Temp. Min./Max. : 9 / 45deg, C

Typical size:
1 Junction Box, Size HXWXD-350X250X15050
2 Junction Box, Size HXWXD-325X220X15050
3 Junction Box, Size HXWXD-250X200X105125
4 Junction Box, Size HXWXD-140X140X9525

Make: SINTEX, HANSEL, CLIPSAL, ESCO, LOTUS FIBRE, UTILEX, FIBCOX
TYPICAL SPECIFICATION
1. 0 Specification for SMC pole junction boxes
1.      Junction boxes shall be made out of Hot press sheet moulded compound   (SMC) as per IS 13410/1992. It shall not be blow moulded.
2.      It should be shock proof, dust proof, fire resistance and pass the rating of UL94V-0.
3.      Box should be equipped with earthing stud in side, clamps with cadmium plating suitable for 6 inch dia pole. All bolts and nuts shall also be cadmium plated.
4.      The material of box shall confirm to grade - S 1 as per IS.
5.      The moulding compound shall be in sheet form sandwiched between two layers
  Of polyethylene sheets.
6.      XXXX should be marked on cover.
7.      Junction Box should not melt at high temperature
8.     Junction Box should be suitable for outdoor use.
2.0  MATERIAL OF JUNCTION BOX:
1. Material of construction of                          junction box shall be THERMOSETTING PLASTIC i.e.  Glass  Reinforced  Polyester Sheet  Moulding   Compound  (SMC)  as  per  IS:13410-1992  and confirming to the requirements of the specification.
2. All M.S. parts should be zinc passivated.
3.  Hinges shall be made out of Anticorrosive material.

3.0 CONSTRUCTION:
1.      Junction Box shall comprise of a moulded base and moulded door.
2.      Thickness of SMC Door/ base will be minimum 2mm.
3.      The door in closed position should be overlapped of base such as to protect electrical item from ingress of external solid, dust and liquid object.
4.      All the corners of the junction box should be round and not pointed ones.
5.      2 Nos. clamps on backside box, having min.20mm. wide shall be provided for fixing of box on the pole.
6.      Suitable bus bar or 4 way connector, stud type in side to be provided in Item for 3P+N,415V, AC.
7.      One no MCB channel L-90mm inside to be provided in each JB.
8.      One no. nipple arrangement having ID 20mm to be provided in each JB

4.0  TECHNICAL PARTICULARS OF SMC JUNCTION BOX
Sr.no.
Particulars
Detailed Particulars
1.
Material
Thermosetting
Plastic
2.
Grade of Material
SMC Ref.  Standard
IS: 13410-1992. Grade S1
3.
Thickness of base/ door (min.)
2mm. (min.)
4.
Properties of Material of construction of Junction Box

(a) Heat Deflection
Temperature ( Ref. Std. IS: 13411)
170o C (Minimum)

(b) Melting Point ( Ref. Std.
IS: 13360)
Does not melt
5.
Exposure to flame( Ref. Std. IS:
4249)
Self-extinguishing
6.
Degree of protection
IP-42    as    per    IS-
12063/87

Dielectric Strength at 90o   C in
Oil.
9  KV/mm(Min)   as
per IS: 6262-1971
7.
Clear    inside    dimensions     of
Junction Box
Submit drawing

8.
Pole  mounting arrangement
Submit drawing

9
Earthing arrangement
Submit drawing
10.
Mounting arrangement
Submit drawing
11.
Wire entry/Cable entry
Submit drawing
12.
Colour
Off white /Siemens gray
13
Hardware
SS
14
Rubber  gasket
Neoprene  


5.0 CERTIFICATION-
·        Test report from CIPET, Ahmadabad/ ERDA, Baroda/ EQDC, Gandhi Nagar if any to be submitted.
·         Routine test/ type test if any to be submitted.







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