From bottles and plastic bags to toys, pipes, credit cards, and medical equipment, polyvinyl chloride (PVC) is one of the world’s most commonly used plastics.
For electrical workers, PVC is one of several insulation options for protecting conductors. But how does it work as an insulation, and what applications make the most sense?
Polyvinyl chloride, AKA vinyl, was one of the first plastics discovered. Today, it’s the third-most produced plastic polymer, behind only polyethylene (PE) and polypropylene.
To make PVC, vinyl chloride monomers, reactive molecules that react with other reactive molecules, undergo a process called polymerization. During this process, chemical bonds turn the monomers into a polymer chain. Once complete, the result is light, strong, fire-resistant PVC.
Sometimes manufacturers use additives to make PVC stronger, more rigid, or water resistant, or plasticizers to make it softer and flexible.
Generally, PVC operates well in temperatures from –20°C to 60°C, though additives can improve its temperature rating to a range of –55°C to 105°C.
Polyvinyl chloride is about 200 years old (FIRST discovered in 1838, then again in 1872), but its real history begins in the 1920s.
B.F. Goodrich scientist Waldo Semon was the first to create plasticized PVC, a flexible, durable, and inert product. His discovery sparked a flurry of innovation, leading to the PVC material used for wire and cable products today.
PVC works well across a wide range of wet and dry temperatures, from -25°C to 75°C. It also excels in many locations, as it’s fire, moisture, abrasion, gas, oil, acid, and chemical-resistant.
Electrical wire and cables can have standard PVC, semi-rigid (SR-PVC), or plenum PVC insulation. Plenum cables must meet stricter fire tests and may call for low-smoke PVC insulation.
Why do some installers choose PVC over other wire insulation types? The insulation has some welcome benefits.
When cost is a concern, PVC cable jackets are less expensive than other options and more readily available.
PVC is common for low- and medium-voltage wiring projects used in open-air environments. Often, this is used as a jacket, lowering costs and keeping projects on budget.
Additionally, unlike other insulations, PVC is 100% recyclable. Other plastic insulations may need polymers for strength and elasticity, making them harder, if not impossible, to recycle. PVC offers great protection without additives, so it’s easier to strip from conductors and recycle into other things.
PVC products are flame-retardant, also known as FR-PVC. Unfortunately, because of their high chlorine makeup, PVC insulation could be lethal when burned.
To soften the plastic and make it usable for other applications, including wire insulation, we need other additives. These include materials like plasticizers, fillers, heat stabilizers, and UV absorbers that enhance the insulation’s properties.
Of course, the additives needed for flexibility and protection reduce PVC’s natural flame-retardant abilities. Manufactures then add agents for other protection.
In the 1980s and 1990s, technology caught up with PVC development. Scientists produced new plasticizers and additives, which improved its fire and smoke retardance beyond its natural capabilities. These new additives allowed PVC materials to work in new applications, including plenum spaces.
Today, PVC provides excellent flame resistance compared to other insulations, including HDPE, polypropylene, and nylon.
Pure PVC is rigid, but additives can be incorporated to improve flexibility without losing strength and durability.
PVC wire insulating material performs well across a wide temperature range, but also carries oil, chemical, and abrasion resistances. When the wire or cable needs more protection, other additives can improve sunlight, water, and heat resistance.
Although PVC gets plenty of high marks for its protective capabilities, it isn’t perfect.
Depending on the application and environment, it might be best to look at other options beyond standard PVC insulation.
Attenuation occurs when there’s a loss of signal strength or amplitude as the signal moves along a wire.
Although attenuation is natural and some signal is always absorbed, rising resistance, long runs, and high frequencies could also cause problems.
To reduce signal loss, projects may use larger gauge conductors or shorter runs. Larger wires and cables have more surface area, allowing more current to pass through. Shorter runs result in less drop-off as current flows through the conductor, leading to better signals.
Most PVC compounds do not have extremely high and low temperatures, ranging from -20°C to 60°C. In some special cases, formulations may allow PVC to operate in conditions as low as –55°C and as high as 105°C.
For common PVC formula, conditions deteriorate once temperatures surpass 70°C. At this point, the insulation will soften or melt, exposing conductors and reducing performance.
This is because manufacturers apply PVC insulation using a thermoplastic process. Other insulations like XLPE use a thermoset process, creating stronger molecular bonds. As a result, polyethylene insulations offer excellent heat resistance while PVC provides good protection but can reach an excellent rating through unique formulations.
PVC is generally more flexible than other insulations because of its thermoplastic process but becomes brittle in extremely low temperatures.
When temperatures drop below 10°C (14°F), PVC insulation becomes harder to bend. At that point, it will stiffen and become brittle. Unlike XLPE insulation, which doesn’t lose bendability in colder temperatures, PVC’s weaker molecule chains struggle.
Cold temperatures combined with pressure can cause PVC to snap or crack, exposing conductors and putting people at risk.
When jobs require a flexible, durable, low-cost cable, PVC gets the job done safely and reliably.
PVC insulated wire has a wide range of applications across several industries, including:
When cost is considered, PVC punches above its weight. Its chemical makeup and durability are useful across many applications, from underground installations and grounding to industrial and commercial options.
No matter what, understand every aspect of the application before buying wire.
Every project is different. Sometimes, PVC seems like a great way to reduce upfront costs but may cause problems later.
An electrical distributor or manufacturer like Kris-Tech can walk you through the process and find the best insulation and wire for the job.
Subscribe to the Kris-Tech Blog
