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4-2 Installing Conductors

Nearly all types of wire may be used in conduit installation; however, the most common type used is moisture-resistant thermoplastic (TW). To determine the length of wire to be installed, add the length of conduit and the length of wire to be left in the boxes for connections (usually 6 inches for each outgoing wire). If the conductors are to be connected into the breaker panel add conductor lengths, in feet, equal to the length and width of the breaker panel.

The general procedure for installing conductors in conduit is the same for all types of conduit. Conductors are installed by pulling them through the conduit. The pulling is done with a special tool called a fish tape (Figure 4-15).

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Figure 4-15. Fish tape

The fish tape is fed through the conduit from its storage reel. The tape is fed in at a box installed for a switch or receptacle. The tape is pulled out of the next opening in the line away from the panel box (Figure 4-16).

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Figure 4-16. Use of the fish tape

Conductors are fastened to the end of the tape. The tape is then pulled or reeled in to draw the conductors through the conduit. If the run is long, two people are needed for this job. One feeds the conductors in at one end as the other reels in the fish tape.

In most cases, there will be more than one conductor being fed into the conduit. It is important to keep the conductors smooth and free of kinks. Set up the conductor spools so that they unwind freely and can be kept free of bends and crossovers.

When more than one conductor is to be pulled, the connection to the fish tape should be staggered to avoid a bulky connection that would make pulling difficult (Figure 4-17.)

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Figure 4-17. Connecting conductors to the fish tape

If the conductors become twisted, they are difficult to pull around bends. For particularly long runs or where there are many bends, wires can be coated with a lubricating compound. Noncorrosive lubricating components are available in dry powder form and in paste.

Sometimes, nonmetallic cable, rather than individual conductors, is installed in conduit. This is done in locations where special protection is needed, such as below grade in residences. The extra stiffness and larger diameter of cable require that special care be taken when feeding the cable into the conduit to avoid damage to it.

The procedure of pulling conductors between switch or receptacle boxes is continued until the complete system is wired. Sometimes, if no switch or receptacle box is called for on a long run, a conduit body must be installed near the middle of the run to make conductor installation easier. Conduit bodies can be used as pull boxes by opening the hatch. Be sure to leave at least 6 inches of wire at each box to make connections to the switch, receptacle, or fixture that will be installed later.

NOTE: A pull box is used at the mid-point for long runs of conduit. Conductors are pulled from the pull box to the start of the run. Then, conductors are pulled from the mid-point (pull box) to the end of the run. This eliminates the need to pull heavy conductors over long distances. Friction between conductors, the conduit, and the weight of the conductors can cause wire (conductor) pulling to be very difficult.

Whenever possible, run conductors from box to box without a break. In particular, the white- or gray-insulated (neutral) wire should be continued unbroken. When the fish tape has been reeled in, hold the red or black conductors and pull out enough white wire to reach the next box or the end of the run. At each box where a connection must be made, leave a loop of white wire. The wire can be connected by removing a section of insulation without cutting the conductor. In many cases, the red and black wires can also be continued in this manner. Continuing conductors in this way reduces the number of connections that must be made in electrical boxes. This speeds up work and keeps boxes uncrowded.


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David L. Heiserman, Editor

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Revised: June 06, 2015