Assumption University
Thailand
EE4503
Electrical Systems Design
Raceways
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Assumption University
Thailand
Topics
• Introduction to Raceways
• Conduits
• Conduit Installations
• Wireways, Auxiliary Gutters, Cable Trays
• Fittings
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Raceways
• Damage e.g. physical, chemical
• Human Contact
• Easy Wiring e.g. wiring, maintenance
• Grounding for Metal Conduit
• Limit the scope of damage e.g. fire, short
circuit
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Conduits – RMC, IMC, EMT
Catalog of Panasoics
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Conduits – RMC
Rigid Metal Conduit
• Strongest conduit (except concrete :p)
• (Usually) Galvanized
• Usage: All weather, all terrain
• Standard:
1
”
2
– 6” (15mm – 150mm) and
3m length
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Conduits – IMC
Intermediate Metal Conduit
• Thinner than RMC
• (Usually) Galvanized
• Usage: All weather, all terrain
• Standard:
1
”
2
– 4” (15mm – 100mm) and
3m in length
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Conduits – EMT
Electrical Metallic Tubing
• Thinner than IMC & RMC
• Not allow to have thread
• Usage: Only in building (not under
ground, not for high voltage)
• Standard:
1
”
2
– 4” (15mm – 100mm) and
3m in length
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Conduits – FMC
http://www.delikon.com/brass.htm
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Conduits – FMC
Flexible Metal Conduit
• Metal conduit with the high flexibility
• Usage: Vibration or Need Bending
• Standard:
1
”
2
– 3” (15mm – 80mm)
• Installation: Need support every 1.5m and 0.3m
(in case of termination point / junction box)
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Conduits – RNC
Rigid Nonmetallic Conduit
• Built from nonmetallic material: e.g. PVC
• Disadvantage: Not as strong as metal and limit
temperature usage
• Advantage: Sustain to erosion, humidity, impact
• Usage: Exposed, Conceal, Wet & Himid or
underground (usually using “duct bank”)
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Conduits – RNC
Duct Bank
http://www.chana.egat.co.th/newweb/gallery/?level=picture&id=28
http://www.iowaconcrete.com/node/707
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Conduits – Comparison
http://www.mc2-ice.com/services/estref/popular_conversion_files/electrical/conduit_weight.html
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Conduits Installation: RMC, IMC
Wet Location: accessories needed to be specified as
“Raintight” or “Wet locations”
http://www.mikeholt.com/instructor2/img/product/pdf/1259687476sample.pdf
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Conduits Installation: RMC, IMC
Cinder Fill: In corrosive area (e.g. under
permanently moist), required at least 2” concrete
Electrical Systems Design: ประสิ ทธิ ์ พิทยพัฒน์
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Conduits Installation: RMC, IMC
Box: Where conduit reaching the box, “bushing” is
required to protect the cable’s
http://www.electrix.co.uk/view_product_options.php?id=1117
http://ecmweb.com/site-files/ecmweb.com/files/archive/ecmweb.com/images/112ecmCBfig1.jpg
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Conduits Installation: RMC, IMC
Bend: Number of bends in one run should <= 360o
Electrical Systems Design: ประสิ ทธิ ์ พิทยพัฒน์
http://www.tpub.com/ceb/71.htm
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Conduits Installation - Supports
Electrical Systems Design: ประสิ ทธิ ์ พิทยพัฒน์
http://www.ci.oceanside.ca.us/civica/filebank/blobdload.asp?BlobID=22230
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Conduits Installation: RMC, IMC
Splices and Taps: only inside the box
http://www.diyadvice.com/diy/electrical/fans-heat/whole-house-ventilating-fan/
http://www.familyhandyman.com/DIY-Projects/Lighting/Kitchen-Lighting/how-to-install-under-cabinet-lighting-in-your-kitchen/View-All
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Conduits Installation - # of Cables
• Need space inside conduit:
– Heat Ventilation
– Cable’s insulator will not be damaged.
http://www.simpullsolutions.com/documents/SIMpullTHHNInstallationandApplicationGuide8-15-07.pdf
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Conduits Installation - # of Cables
table
http://www.telepart.net/ตารางการติดตัง้ สายไฟในทอWire-Conduit-Table.html
่
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Conduits Installation - # of Cables
calculation
Calculate directly from the cable’s outer
diameter (𝑑) and conduit’s inner diameter
(𝐷) and 𝑛 is the number of cables.
%𝐹𝑖𝑙𝑙 =
𝑑
𝑛∗𝜋
2
𝐷 2
𝜋
2
2
𝑑
∗ 100 = 𝑛 ∗
𝐷
2
∗ 100
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Wireways
http://www.indochinaengineering.co.th/product.php?id_product=30
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Wireways
• Raceways are folded from sheet metal.
• General usage in open area. If outside
building, specify “Raintight”
• Not use when risk of severe physical
damage.
• Height: 50, 75, 100, 150, 200 mm
• Width: 50, 75, 100, 150, 200, 250, 300 mm
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Wireways
• Use current rated for the metal conduit.
• Use reduction factor, if > 30 cables.
• Need supports for every 1.5m.
• Cannot use through the wall or floor.
• Cannot use as grounding cable.
• Use no more than 20% fill.
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Auxiliary Gutters
• Similar to wireways
• Collect the cable before distribute.
http://www.contractortalk.com/f32/some-recent-work-34277/
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Cable Trays
http://www.indochinaengineering.co.th/product.php?id_product=32
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Cable Trays
• Cable Tray is not Raceways, but is
commonly used in industry to support
cable.
• Cheap and easy to use.
• Only for specific cable types, e.g. multicore cables
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Cable Trays – Ladder Type
For heavy-duty power distribution
http://www.shreemahalaxmisteel.com/cable-trays.html
http://www.ezziengineering.com/images/Cable_Tray_Catalogue.pdf
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Cable Trays – Perforated Type
For power cables, small cables and control
cables
http://www.shreemahalaxmisteel.com/cable-trays.html
http://www.ezziengineering.com/images/Cable_Tray_Catalogue.pdf
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Cable Trays – Solid Bottom Type
For small cables.
http://www.ezziengineering.com/images/Cable_Tray_Catalogue.pdf
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Cable Trays – Comparison
http://www.cooperindustries.com/content/dam/public/bline/Resources/Library/catalogs/cable_tray_systems/all_products/CTManual.pdf
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Fittings
• Accessories to be used with race way.
• Purpose
– To firmly hang the raceway
– To smoothly change the direction of raceway
– To easily pull the cable into the raceway
– To properly splice the cables
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Fittings - Boxes
• Termination point (switch, receptacle) or
Stop point (splice, tap) for the wiring
system.
• Metal or non-metal.
• Sizing is based on the required space.
• Have no hole for the object larger than 7.5
mm in diameter to pass thru.
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Fittings - Boxes
http://www.topaz-usa.com/catalogs/electrical_fittings_catalog.pdf
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Fittings – Pull Boxes
http://ecmweb.com/code-basics/sizing-junction-boxes
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Fittings – Pull Boxes
straight pulls
The horizontal
dimension (A)
is 8 times of the
largest raceway
size.
http://ecmweb.com/code-basics/sizing-junction-boxes
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Fittings – Pull Boxes
angle pulls
The distance between
raceways (C) is 6 times
of the diameters of the
raceways.
http://ecmweb.com/code-basics/sizing-junction-boxes
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Fittings – Other Accessories
Connectors
• Steel Coupling
• Compression
• Set Screw
• Rain Tight
http://www.topaz-usa.com/catalogs/electrical_fittings_catalog.pdf
http://numthaveerung.co.th/pdf/Steel%20Conduit-Accessories%20Fitting.pdf
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Fittings – Other Accessories
Bushing
• Metal
• Non-metal
• Grouding
http://www.topaz-usa.com/catalogs/electrical_fittings_catalog.pdf
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Fittings – Other Accessories
Elbow & Strap
• Elbow
• Strap
http://www.topaz-usa.com/catalogs/electrical_fittings_catalog.pdf
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Reference
• Electrical Systems Design: ประสิ ทธิ ์ พิทยพัฒน์
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