Polyvinyl chloride or PVC is a common jacketing material across the electrical industry. You can see them as cable jackets for many applications, in low-voltage harnesses, computers, telecom, etc. Why does the PVC jacket get popular? What characteristics does the coat jacket have?
PVC and PVC Jacket Rating
Usually, the jacket materials have the physical strength to endure oil, flame, and weathering. However, to remove its resistance to environmental factors, you must compound it with additives like plasticizers, fillers, and stabilizers.
PVC can be hazardous in fires as it releases a large amount of smoke and hydrogen chloride gas. These gases can irritate humans and lead electronic devices to corrosion. On the other hand, PVC is usually rated as unsuitable for use in plenum space.
PVC cables have ratings of CMR/CMG/CM as per the National Electrical Code (NEC).
CM/CMG: You can use communications cable for almost anything. For example, it is common in all kinds of buildings, in compliance with the NEC’s Article 800.53(E) (1). These cables resist spreading the flames in Vertical Tray Flame Test. Thus, it is suitable for installations in cable trays and other non-riser, non-plenum areas.
CMR (Riser): A riser is a section of a building’s telecommunications system that runs vertically from one level to the next. According to NEC Section 800.53(B), CMR is designed for installation in vertical shafts within structures. The UL 1666 standard specifies the test for CMR cables, which places restrictions on how far a fire may spread.
Benefits of PVC Jacketed Cables
PVC is considered to have versatile applications. Typical Benefits of using PVC are
- It is adaptable to new changes, although PVC is stiff and rigid. Thus, you can compound it with fillers and other plasticizers and enhance its properties.
- PVC is easy to process and recycle as you use it like a thermoplastic.
- Cables that have PVC sheathing are flame retardants. Moreover, it can resist chemicals like acids, oils, and alkalis and endure abrasions.
- When you process it with additives, the temperature range can increase from -40 to 105 degrees centigrade. Thus, PVC insulation can be sunlight resistant and waterproof.
- The cross-linked version is another version of PVC that the defense and automotive industries use. It has improved temperature resistance, and dielectric strength. So, even a thin layer of insulation can suffice.
Caption: Metallic and Fiber cables with PVC insulation
Limitations of PVC Cable
When considering a PVC cable, you also have to consider its limitation.
Tendency to creep under continuous pressure
Since the PVC tends to get damaged when it has to face pressure, it does not work well if you use it in insulated pipes where continuous hanging is necessary. For that, you can choose Hypalon or neoprene in these applications.
Low Voltage Application
PVC is present in low voltage. Melting might irreversibly destroy the insulation or emit plasticizers, causing it to stiffen and become brittle. Thus, it is not utilized as a backup network cable.
Similarly, PVC is avoided in businesses that handle significant volumes of hot material or where there is a risk of excessive heat. When utilizing PVC cables, keep in mind the halogen-based chemicals and smoke emitted if they burn. Although it usually requires a high temperature to ignite, it is not commonly employed in densely crowded structures.
This incident exemplifies one of the most severe issues that can arise from the usage of PVC. During a fire, flames can emit a significant amount of chlorine. Hydrochloric acid may be formed when mixed with moisture.
Susceptible to UV light and water
Another disadvantage of PVC is that it is vulnerable to ultraviolet radiation and can fracture or become brittle if exposed to the sun for an extended period. PVC requires extra jacketing or unique additives to protect the cable core when used in outdoor cables to function correctly.
PVC is water-resistant, but its performance is significant in how long it will remain in wet locations. For example, if a PVC jacketed wire comes into touch with water, it will immediately dry up and pose no danger. Water will eventually eat through the PVC insulation if left unattended for an extended period. Thus, many manufacturers do not recommend regular PVC cables for underwater installations.
Caption: High voltage PVC insulated wire bundle
Alternatives to PVC Jacketing
There are different types of cable jackets you can try.
CMP (Plenum) Cable
“Plenum” cables are present with materials as covers that don’t make a lot of smoke and slow down the spread of flames. Jackets made of FEP are a popular choice. Even though “plenum cables” and “PVC cables” are often classified as two separate things, manufacturers use PVC compounds to make jackets for the plenum areas.
As the NEC defines, CMP is a type of cable that you have to install in plenum airspaces in a building, like in the ceiling. The NFPA 262 standard defines the most common test for CMP cables. These standard list low smoke and fire performance requirements and is a common choice for the quality assurance team.
Low Smoke Zero Halogen cables reduce the quantity of harmful and corrosive gases released during a fire. Many electricians use them in poorly ventilated places, such as trains and other modes of transportation. The usage of LSZH cable is widespread in the railway sector, particularly on the London Underground. If the manufacturers have labeled them as ‘LSZH cables,’ LSZH cables must pass three tests related to halogen concentration, low smoke density, and flame propagation.
LSF cable is another type of less smoke and fume cable. They are not the same as LSHZ cables. Moreover, the LSF cable is not suitable for places where you need to apply the LSHZ cables. Hence, it is essential to double-check the cable.
Most oils, fluids, and fuels do not harm PTFE. They can withstand very high-temperature ranges, making them less vulnerable to damage from usage in situations where the ambient temperature prohibits the use of PVC cables.
Typical PTFE cables with silver-plated conductive material can withstand maximum temperatures of 200 to 250 degrees centigrade. Moreover, nickel-plated wires that can withstand up to 260 degrees Celsius temperatures are also available; however, they are less frequent. Additionally, fiberglass twisted wires can withstand temperatures as high as 400 degrees centigrade.
In difficult locations, PUR polyurethane-wrapped cables are the ideal choice. The sheathing is both a strength and a weakness in PUR cable since strip ability may be an issue.
PTFE cables and silicone-sheathed cables are similar in that you use them in conditions when the ambient temperature is high. However, silicone-sheathed cables cannot endure temperatures to the same extent as PTFE cables. Also, they do perform admirably at colder temperatures. Due to its high heat resistance and enhanced flexibility, unlike PTFE, it has gained widespread acceptance in the industry. In addition, as compared to PVC, they emit less smoke and smells in fire scenarios.
Rubber jacketed cables are typically utilized outdoors and wet, with certain exceptions. The sheathing material is most commonly used for power cords, particularly high-power main wires that you use outdoors.
Caption: Rubber insulated copper wire
PVC is common non-metallic material for jacketing, accounting for about half of all applications. Since 1935, the usage of PVC has increased dramatically, owing to its low cost, ease of processing, and a good combination of overall qualities, including chemical and fire resistance. Here at Bloom, we offer wiring harnesses and cable assemblies. If you have any questions concerning the material, please do not hesitate to contact us.