Conduit and Raceway Systems
A conduit is something that transports materials from one place to another. An
electrical conduit is a piping system that is used to route and protect electrical
wires. An electrical conduit can be made from metal, plastic, fiber, or fired clay. A
flexible conduit can be used for special purposes. It is installed at the site where
electrical equipment is being installed to connect the elements of the PV system.
The details of its use, form, and installation are outlined in the US National Elec-
trical Code. The NEC must be followed because all conduits do not work the
same way or have the same properties and cannot be used for the same electrical
purposes. Knowledge of the specifics here is important.
Raceways are metal or plastic pieces of conduit that are used to protect the
conductors and when properly installed often provide a more eye-pleasing pas-
sage for wiring. Aesthetics often speaks volumes about the installers’ workman-
ship and sense of thoroughness. In short, nobody likes a sloppy or ugly
installation.
Refer to NEC 2011, Article 384, for Strut-Type Channel Raceway, Article 386
for Surface Metal Raceway, Article 388 for Surface Nonmetallic Raceways, and
Article 390 for Underfloor Raceways.
The raceway usually has an open face and a cover that can be removed. It
may be mounted to the wall where the conductors or conduit are laid carefully
inside in an organized manner. The advantages of raceways are that they allow
conductors to be installed without having to remodel an entire room or area and
the wires are easy to access for future maintenance or testing. Also, the raceway is
designed to safely provide a barrier for the conductors from damage and access
by the people living or working in the building.
When a system has two or more insulated conductors that have an overall
protective covering, it is called a cable. The covering is used for specific reasons.
This protective covering, which acts as an insulated conduit or raceway, may be
rated for resistance to moisture, UV light, heat, chemicals, or abrasion. Different
cables are used for different reasons. NEC 2011 contains tables and lists of the
types of cables, their characteristics, what and when they are best used.
What is important here is how those cables are enclosed. In PV systems, wire
needs to be concealed or protected and this is where conduits and raceways come
into play.
Liquid Tight is a flexible conduit, which is a metallic or nonmetallic plastic-
wrapped conduit that is used to connect module junction boxes and other BOS
components where flexibility is required. Another commonly used conduit in PV
systems is polyvinyl chloride (PVC) pipe. There are many kinds of PVC that in
this case are rigid, nonmetallic, and have very specific requirements for usage.
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