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Conduit System
Conduit System
The noun conduit comes from root words meaning "pipe," and the word retains this definition.
Types of conduit
Types of conduit
PVC or plastic conduit
A PVC electrical conduit is commonly known as a white rigid PVC tube for threading and protecting wires from corrosion and electrical leakage. The most basic of the home improving is the installation of wire layout. PVC conduit pipes offer several advantages over steel conduit pipes. For one, they are much lighter in weight, making them easier to install and transport. They are also corrosion-resistant and do not require coatings or treatments to protect against rust or degradation.
metal conduit
The basic types of steel race ways in use today are steel rigid metal conduit (RMC), intermediate metal conduit (IMC) and electrical metallic tubing (EMT). Galvanized rigid conduit is the most popular type of RMC, excellent for applications in industrial and commercial buildings. PVC-coated aluminum is excellent for applications where chemical fumes can corrode the steel. Bronze alloy works well in chemical plants, coastal areas, underwater, and oil refineries.
Class 4 conduit
Class 4 conduit
Barton Class 4 conduit is Hot Dipped Galvanized, a process where steel products are coated with zinc by immersing them in a molten zinc bath at a temperature of approximately 450 °C. Trace elements of alloying metals such as lead, aluminum and nickel are included to improve fluidity and reduce dross.
The difference between
class 3 conduits is made by pre galvanized steel strip,
class 4 conduit is made by hot dipped galvanized strip. Hot-dip zinc coated steel to BS 2989 and with a minimum coating designation of G275.
Sizes
Sizes
Conduit sized are identified by diameter of the pipe.
3/4" or 19mm - common for general circuit
1" or 1" ½
2" ~ 4"
6"
10" ~ largest size market can offer.
Accessories
Accessories
Conduit piping system comes with complete accessories for installation purpose on site.
conduit jointer
L angle
conduit adaptor or 'male-female bush'
Safety and grounding
Safety and grounding
Conduit system (if using galvanize iron or steel conduit pipes) is required to be grounded or connected with CPC (circuit protective conductor).
Requirement in conduit piping system
Requirement in conduit piping system
Galvanize conduit are not painted there for standard color for representing electrical circuits must be painted with ORANGE color.
IEE Regulation on conduit system
IEE Regulation on conduit system
A system of conduits into which unsheathed cables can be drawn has long been a standard method for electrical installations. The Regulations applying to conduit systems may be summarized as follows:
All conduits and fittings must comply with the relevant British Standards.
Plastic conduits must not be used where the ambient temperature or the temperature of the enclosed cables will exceed 60°C. Cables with thermo setting insulation are permitted to run very hot, and must be suitably down-rated when installed in plastic conduit. To prevent the spread of fire, plastic conduits (and plastic trunking) must comply with ignitability characteristic 'P' of ES 476 Part 5.
Conduit systems must be designed and erected so as to exclude moisture, dust and dirt. This means that they must be completely closed, with box lids fitted. To ensure that condensed moisture does not accumulate, small drainage holes must be provided at the lowest parts of the system.
Proper precautions must be taken against the effects of corrosion , as well as against the effects of flora (plant growths) and fauna (animals). Protection from rusting of steel conduit involves the use of galvanised (zinc coated) tubing, and against electrolytic corrosion the prevention of contact between dissimilar metals eg steel and aluminium. Any additional protective conductor must be run inside the conduit or its reactance is likely to be so high that it becomes useless if intended to reduce fault loop impedance.
A conduit system must be completely erected before cables are drawn in. It must be free of burrs or other defects which could damage cables whilst being inserted.
The bends in the system must be such that the cables drawn in will comply with the minimum bending radius requirements . According to regulation, the radius of every conduit bend shall be not less than 2.5 time the overall diameter of the conduit. Where cables other than conduit wiring cables are installed in conduit, the radius of conduit bends shall be increased.
The conduit must be installed so that fire cannot spread through it, or through holes cut in floors or walls to allow it to pass. This subject of fire spread .
Allowance must be made, in the form of expansion loops, for the thermal expansion of long runs of metal or plastic conduit. Remember that plastic expands and contracts more than steel.
Use flexible joints when crossing building expansion joints.
When conduit is used as a protective conductor,the earthing terminal of each accessory and socket outlet shall be connected by a protective conductor to an earthing terminal fixed in the associated box or other enclosure.
Solid elbows or tees are generally only allowed immediately behind an accessible outlet box, inspection fitting or lamps. Where a conduit run does not exceed 10 meters between outlet points and the sum of all bends between the outlet is 90 degree bend or less. A solid elbow may be installed up to 500mm from an accessible outlet box.
Conduits accessories
Conduits accessories
Recommendation conduit system installations
Recommendation conduit system installations
Topic relates : Trunking system
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