engineering

Outside plant

Outside plant is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Outside plant rather than just read about it. In short: In telecommunications, the term outside plant has the following meanings: In civilian telecommunications, outside plant refers to all of the physical cabling and supporting infrastructure (such as conduit, cabinets, tower or poles), and any associated hardware (such as repeaters) located between a demarcation point in a switching facility and a demarcation point in another switching center or customer premises. In t…

Key takeaways

Outside plant belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Outside plant to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Outside plant from memory before moving on to harder problems.

Reference excerpt

In telecommunications, the term outside plant has the following meanings:

In civilian telecommunications, outside plant refers to all of the physical cabling and supporting infrastructure (such as conduit, cabinets, tower or poles), and any associated hardware (such as repeaters) located between a demarcation point in a switching facility and a demarcation point in another switching center or customer premises. In the United States, the DOD defines outside plant as the communications equipment located between a main distribution frame (MDF) and a user end instrument. The CATV industry divides its fixed assets between head end or inside plant, and outside plant. The electrical power industry also uses the term outside plant to refer to electric power distribution systems.

Context

Network connections between devices such as computers, printers, and phones require a physical infrastructure to carry and process signals. Typically, this infrastructure will consist of:

Cables from wall outlets and jacks run to a communications closets, sometimes referred to as station cable. Cables connecting one communications closet to another, sometimes referred to as riser cable. Racks containing telecommunications hardware, such as switches, routers, and repeaters. Cables connecting one building to another. Exterior communications cabinets containing hardware outside of buildings. Radio transceivers used inside or outside buildings, such as wireless access points, and hardware associated with them, such as antennas and towers. The portion of this infrastructure contained within a building is the inside plant, and the portion of this infrastructure connecting buildings or facilities is the outside plant. Where these two plants meet in a given structure is the demarcation point. Outside plant cabling, whether copper or fiber, is generally installed as aerial cable between poles, in an underground conduit system, or by direct burial. Hardware associated with the outside plant must be either protected from the elements (for example, distribution frames are generally protected by a street side cabinet) or constructed with materials suitable for exposure to the elements. Installation of the outside plant elements often require construction of significant physical infrastructure, such as underground vaults. In older large installations, cabling is sometimes protected by air pressure systems designed to prevent water infiltration. While this is not a modern approach, the cost of replacement of the older cabling with sealed cabling is often prohibitively expensive. The cabling used in the outside plant must also be protected from electrical disturbances caused by lightning or voltage surges due to electrical shorts or induction.

Example: copper access network In civilian telecommunications, the copper access network (also known as the local loop) providing basic telephone or DSL services typically consists of the following elements:

In-house wiring that connects customer premises equipment to the demarcation point, usually in residential installations contained in a weather protected box. One or more twisted pairs, called a drop wire. The drop wires typically connect to a splice case, located in line for aerial cables, or in a small weather protected case for underground wiring, where the local cabling is connected to a secondary feeder line. These cables contain fifty or more twisted pairs. Secondary feeder lines run to a streetside cabinet containing a distribution frame called a Serving Area Interface (SAI). The SAI is connected to the main distribution frame, located at a Telephone exchange or other switching facility, by one or more primary feeder lines which contain hundreds of copper twisted pairs. An SAI may also contain a Digital subscriber line access multiplexer (DSLAM) supporting DSL service. Active equipment (such as a POTS or DSL line circuit) can then be connected to the line in order to provide service, but this is not considered part of outside plant.

Protecting equipment in the outside plant

The environment can play a large role in the quality and lifespan of equipment used in the outside plant. It is critical that environmental testing criteria as well as design and performance requirements be defined for this type of equipment. There are generally four operating environments or classes covering all outside plant (OSP) applications, including wireless facilities.

Class 1: Equipment in a Controlled Environment Class 2: Protected Equipment in Outside Environments Class 3: Protected Equipment in Severe Outside Environments Class 4: Products in an Unprotected Environment Electronic equipment located in one or more of these environmental class locations is designed to withstand various environmental operating conditions resulting from climatic conditions that may include rain, snow, sleet, high winds, ice, salt spray, and sand storms. Since outside temperatures can possibly range from −40 °C (−40 °F) to 46 °C (115 °F), with varying degrees of solar loading, along with humidity levels ranging from below 10% up to 100%, significant environmental stresses within the enclosure or facility can be produced. Telcordia GR-3108, Generic Requirements for Network Equipment in the Outside Plant (OSP), contains the most recent industry data regarding each Class described above. It also discusses what is currently happening in ATIS and Underwriters Laboratories (UL). The document also includes

Environmental criteria such as operating temperatures, humidity, particulate contamination, pollution exposure, and heat dissipation Mechanical criteria such as structural requirements, packaging, susceptibility to vibration, earthquake, and handling Electrical protection and safety including protection from lightning surges, AC power induction and faults, and Electromagnetic Interference (EMI), and DC power influences

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Outside plant

Start with the simplest possible case. Write down what Outside plant claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Outside plant before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Outside plant ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Outside plant

In research: Outside plant appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Outside plant in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Outside plant is common in secondary-school and first-year university syllabi. It links to neighbouring topics Telecommunications infrastructure, so understanding it makes those chapters shorter.
In everyday life: Look for Outside plant outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Outside plant in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Outside plant means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Outside plant out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Outside plant in simple terms?

In telecommunications, the term outside plant has the following meanings: In civilian telecommunications, outside plant refers to all of the physical cabling and supporting infrastructure (such as conduit, cabinets, tower or poles), and any associated hardware (such as repeaters) located between a…

Why does Outside plant matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Outside plant?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Outside plant.