Selecting A Wiring Method

1. Outdoor Wiring - Overhead

Open wire circuits on insulators were commonly used in older systems for outdoor primary and secondary distribution. This method is normally the least expensive (first cost) method, and is satisfactory in many cases. The conductors, either bare or insulated, may be mounted on poles or attached to buildings. This system does have the serious disadvantage where yard crane traffic is heavy or the area is congested.

2. Outdoor Wiring - Underground

Underground distribution can help solve the congestion problem that is bound to develop in the electrical system of almost any growing plant. The two main types of underground distribution are:

1. Circuits installed in ducts with manholes or pulling chambers provided for splicing, pulling and maintenance.
2. Direct burial installation is somewhat less expensive in first cost than the duct system, but maintenance costs may be higher. Care must be taken to prevent damage to the cable or the covering during the laying operation as well as from "dig-ins.".

3. Indoor Distribution

Each indoor application will differ. Be careful to consider all the facts and weigh all the advantages and disadvantages of each method. Here are a few basic points to keep in mind.

And furthermore . . .

Trolley Busway
Busway (NEC 364)
Wireways (NEC 362)
Open Wiring (NEC 320)
Mineral Insulated Cable (NEC 330)
Conductors In Rigid Conduit (NEC 346 And 347)
Conductors In Flexible Metallic Conduit (NEC 350)
Metal Clad & Non-Metallic Sheathed Cable (NEC 334; 336)