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Raceways

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Raceways are electrical highways of distributing power. Without them, we would have a mass of wires that we couldn't tell apart, and no protection for our circuit.

Raceways are an integral part of what we do everyday, and are essential in keeping our wires safe - inside the conduit, as well as out. There is a particular art in doing a job neatly and organized. When your eye becomes more trained you will notice the difference between a "good" job, and a "masterful" job.

Surprisingly, the masterful jobs that take a little more time planning where the pipe will go initally, and the circuits, ends up taking the electricians less time to pipe because they aren't trying to "saddle" over everybody else's work. This results in a better looking electrical room, and circuits that are easily traced for origin.

Section 12 of the CEC gives uses of raceways, and proper installation.



Different Types of Raceways

- Rigid (CEC 12-1000)
- Flexible Metal Conduit (CEC 12-1000)
- Liquid Tight (CEC 12-1300)
- EMT (CEC 12-1400) Electrical Metallic Tubing
- PVC Rigid (CEC 12-1100)
- Surface Raceways (CEC 12-1600)
- Underfloor Raceways


An overview of the three most commonly used conduit (PVC, EMT, and Rigid)

PVC - Polyvinyl Chloride
- Non metallic suited for damp locations
- Half of the weight of aluminum
- Ease of installation
- Life span is unknown
- Any length can be reused
- Expands and contracts more than other conduit
- Temperature limitation
- Have to install bonding conductor
- Cannot be installed with thermal insulation
- No torches or open flames for installation
- Expansion joints are required after 45mm expansion. See code.


EMT - Electrical Metallic Tubing
- A thin walled metallic raceway
- 10 foot lengths from 1/2" to 4"
- Can be used as a bond
- Bent with one shot or hand bender
- Raintight or Concrete/Dry fittings
- LB, LR, LL, Type T, Type C, Condulets
- Supports one or two hole straps
- Non sparking
- Non magnetic
- Cannot be used in severe chemical reaction or fertilizer petroleum plants.


Rigid
- Aluminum or steel
- Choice of external coatings
- PVC Coated if ordered
- Baked on enamel
- Waterproof, explosion proof, fire proof, and vapour proof.
- Tapered thread (no air flow)
- Metal on Metal contact
- Good mechanical protection
- Bond to ground
- Can be used in hazardous areas
- Aluminum or steel
- No voltage limit
- Readily insulated
- ***Measure, mark, cut, thread



Fittings and Connectors
For conduit the common fittings and devices in the installation are:
- Clamps, brackets, and condulets.
- There are a maximum of 4 - 90 degree bends between outlet boxes.
- All fittings must be accessible.
- Connectors are used to terminate pipes to boxes or fittings.
- Couplings join pipes. Rigid is threaded. EMT may be compression or set screw.
- Locknuts are saucer shaped with small teeth formed with notches facing the box. They bite into the wall of the box, and achieve good bonding continuity.
- Bushings are used to protect conductor insulation. (CEC 12-906) Anything larger than 8 AWG requires insulated bushing type or plastic insert.



Electrical Boxes
Types of electrical boxes and devices for use:
- Device Box (Recpetacle and Switches)
- Octagon Box (Light fixtures or junction box)
- Square Box (Junction box for surface or concealed)
- Round Box
- Masonry Box (In block walls)




Accessories for Electrical Boxes
- Bar Hangers
- Plaster Rings
- Device Box Covers
- Reducing Washers
- Knock-Out Plugs



Calculating Box Fill
To be calculated in order...
- Maximum number of conductors (CEC 12-3036)
- Table 22 (volume required)
- Table 23 (maximum number of conductors)
- Please keep in mind that 12-3036 specifies conditions.



Applications of Use for a Junction Box
There is a Straight Pull Through or Angle ( U Pull) for a junction box. When pullings wires, there needs to be a workable amount of space left for the wires. The CEC has specific codes on pull throughs, and are outlined below.

- Straight Pull Through (CEC 12-3036) (2)(b) 8 x D. D being the largest diameter of conduit.

- Angle ( U Pull) (CEC 12-3036) (2)(c) 6 + D x C. The distance must be increased for the sum of all diameters on the same wall of the pull box.