Frequently asked questions on fiber optic cables

BY Hunan GL Technology Co.,Ltd.

POST ON:2023-04-23

VIEWS 61 Times

Frequently asked questions on fiber optic cables:
1、How much does a fiber drop cable cost?
Typically, the price per fiber optic cable ranges from $30 to $1000, depending on the type and quantity of fibers: G657A1/G657A2/G652D/OM2/OM3/OM4/OM5, jacket material PVC/LSZH/PE, length, and Structural design and other factors affect the pricing of drop cables.

2、Will fiber optic cables be damaged?
Fiber optic cables are often classified as fragile, just like glass. Of course, the fiber is glass. The glass fibers in fiber optic cables are fragile, and while fiber optic cables are designed to protect the fibers, they are more prone to damage than copper wire. The most common damage is fiber breakage, which is difficult to detect. However, fibers can also break due to excessive tension during pulling or breaking. Will fiber optic cables be damagedFiber optic cables are usually damaged in one of two ways:

• Prefabricated fiber optic cables may damage the connectors if excessive tension is applied during installation. This can happen when long fiber optic cables are passed through tight conduits or ducts or when fiber optic cables get stuck.
• The fiber optic cable was cut or broken during operation and needed to be re-spliced to reconnect.

3、How do I know if my fiber cable is damaged?
If you can see a lot of red lights, the connector is terrible and should be replaced. The connector is good if you look at the other end and only see the light from the fiber. It's not good if the whole ferrule is glowing. The OTDR can determine if the connector is damaged if the cable is long enough.

4、How to Choose Fiber Optic Cables based on Bend Radius?
The bend radius of the fiber optic cable is critical for installation. Factors that affect the minimum radius of a fiber optic cable include outer jacket thickness, material ductility, and core diameter.

To protect the integrity and performance of the cable, we cannot bend it beyond its allowable radius. In general, if bend radius is a concern, bend-insensitive fiber is recommended, allowing easy cable management and reducing signal loss and cable damage when the cable is bent or twisted. Below is the bend radius chart.

Fiber Cable Type
Minimum Bend Radius

5、How to test fiber optic cable?
Send the light signal into the cable. When doing this, look carefully at the other end of the cable. If the light is detected in the core, it means the fiber is not broken, and your cable is fit for use.

6、How often do fiber cables need to be replaced?
For about 30 years, for properly installed fiber cables, the probability of failure in such a time frame is about 1 in 100,000.
By comparison, the chance of human intervention (such as digging) damaging the fiber is about 1 in 1,000 over the same time. Therefore, under acceptable conditions, a high-quality fiber with good technology and careful installation should be very reliable - as long as it is not disturbed.

7、Will cold weather affect fiber optic cables?
When the temperature drops below zero and the water freezes, ice forms around the fibers - which causes the fibers to deform and bend. This then reduces the signal through the fiber, at least reducing the bandwidth but most likely stopping data transmission altogether.

8、Which of the following problems will cause the loss of the signal?
The most common causes of fiber failures:
• Fiber breakage due to physical stress or excessive bending
• Insufficient transmit power
• Excessive signal loss due to long cable spans
• Contaminated connectors can cause excessive signal loss
• Excessive signal loss due to connector or connector failure
• Excessive signal loss due to connectors or too many connectors
• Incorrect connection of fiber to patch panel or splice tray

Usually, if the connection fails completely, it's because the cable is broken. However, if the connection is intermittent, there are several possible reasons:
• Cable attenuation may be too high due to poor quality connectors or too many connectors.
• Dust, fingerprints, scratches, and moisture can contaminate connectors.
• Transmitter strength is low.
• Poor connections in the wiring closet.

9、How deep is the cable buried?
Cable Depth: The depth to which buried cables can be placed will vary depending on local conditions, such as "freeze lines" (the depth to which the ground freezes each year). It is recommended to bury fiber optic cables to a deep/coverage of at least 30 inches (77 cm).

10、How to find buried optical cables?
The best way to locate a fiber optic cable is to insert the cable pole into the conduit, then use an EMI locating device to connect directly to the cable pole and track the signal, which, if done correctly, can provide a very accurate location.

11、Can metal detectors find optical cables?
As we all know, the cost of damaging live fiber optic cables is high. They usually carry a hefty load of communications. It is imperative to find their exact location.
Unfortunately, they are challenging to locate with ground scans. They're not metal and can't use steel with a cable locator. The good news is that they are usually bundled together and may have external layers. Sometimes, they are easier to spot using ground-penetrating radar scans, cable locators, or even metal detectors.

12、What is the function of the buffer tube in the optical cable?
Buffer tubes are used in fiber optic cables to protect fibers from signal interference and environmental factors, as they are commonly used in outdoor applications. Buffer tubes also block water, which is especially important for 5G applications because they are used outdoors and are often exposed to rain and snow. If water gets into the cable and freezes, it can expand inside the cable and damage the fiber.

13、How are fiber optic cables spliced together?
Types of Splicing
There are two splicing methods, mechanical or fusion. Both ways offer much lower insertion loss than fiber optic connectors.

Mechanical splicing
Optical cable mechanical splicing is an alternative technique that does not require a fusion splicer.
Mechanical splices are splices of two or more optical fibers that align and place the components that keep the fibers aligned by using an index matching fluid.

Mechanical splicing uses minor mechanical splicing approximately 6 cm in length and about 1 cm in diameter to permanently connect two fibers. This precisely aligns the two bare fibers and then mechanically secures them.

Snap-on covers, adhesive covers, or both are used to secure the splice permanently.
The fibers are not permanently connected but are joined together so that light can pass from one to the other. (insertion loss <0.5dB)
Splice loss is typically 0.3dB. But fiber mechanical splicing introduces higher reflections than fusion splicing methods.

The optical cable mechanical splice is small, easy to use, and convenient for a quick repair or permanent installation. They have permanent and re-enterable types. Optical cable mechanical splices are available for single-mode or multi-mode fiber.

Fusion splicing
Fusion splicing is more expensive than mechanical splicing but lasts longer. The fusion splicing method fuses the cores with less attenuation. (insertion loss <0.1dB)
During the fusion splicing process, a dedicated fusion splicer is used to precisely align the two fiber ends, and then the glass ends are "fused" or "welded" together using an electric arc or heat.

This creates a transparent, non-reflective, and continuous connection between fibers, enabling low-loss optical transmission. (Typical loss: 0.1 dB)
The fusion splicer performs optical fiber fusion in two steps.

1. Precise alignment of the two fibers
2. Create a slight arc to melt the fibers and weld them together
In addition to the typically lower splice loss of 0.1dB, the benefits of splice include fewer back reflections.

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