Electrical Insulation 101

From our humble beginnings as a single-room manufacturer during WWII, ESPE Manufacturing Co. has grown into one of the midwest’s largest suppliers of electrical insulation.

At ESPE, not only do we supply a full range of performance insulators, but we also manufacture high-precision insulating barriers to our clients’ exact specifications. Whatever your insulation needs, ESPE’s ANSI, ASTM, and ISO-compliant fabrication capabilities ensure you receive custom components that work for you.

9 Common Questions About Electrical Insulation

#1 "What is electrical insulation?"

Electrical Insulation

Electrical insulation refers to materials that contain electric current to a specified path. These materials, typically non-metals, are chosen for their extremely low conductivity and correspondingly high resistivity. Although it’s impossible to completely halt electrical flow, insulators block virtually all current from passing through them.

Insulation is commonly associated with rubberized wire coatings, which confine electricity to the circuit for both efficiency and safety purposes. However, electrical insulation is needed in many other applications. For instance, batteries, circuit boards, and generators all require insulation for safe and proper functioning.

#2 "Why is electrical insulation important?"

Electrical insulation is important for two primary reasons: efficiency and safety.

  • Efficiency: Without insulation, most circuitry would not function as intended because the current would spread throughout the system. In minor cases, this leaked current increases energy consumption and reduces system efficiency. In severe cases, improper insulation causes short circuits that destroy nearby components and require systems to be replaced. Isolating the current to a specific path ensures that electricity powers exactly what it should and nothing more. 
  • Safety: Leaked current is not just an efficiency problem, it’s also a significant safety hazard. When electricity flows where it shouldn’t, it can shock nearby employees or start major electrical fires. Insulation prevents these outcomes by blocking the current from exiting a circuit.

#3 "Which materials are best for electrical insulation?"

Electrical insulation should have excellent resistivity to block the flow of electrons, along with sufficient mechanical and dielectric strength to withstand application demands. Many non-metals fulfill these criteria to some extent, and the best choice depends on the application. 

  • Cardboard/Paper: Paper-based materials are the most cost-effective option for low-heat, low-voltage applications, but they lack the durability of other options.
  • Clay: Clay materials, including both ceramic and porcelain, are ideal for high-voltage applications such as bushings for power lines.
  • Glass: Although no longer very common, glass materials such as silica and limestone perform well in low-voltage settings.
  • Formex: Formex is a flame-retardant polypropylene used to protect against electrical surges in many consumer and industrial electronics. This insulating material is economical, versatile, and resists moisture.
  • Mica: Mica is a durable choice for applications that may involve environmental exposure. Its combination of electrical insulation and thermal conduction properties make it ideal for use in capacitors.
  • PTFE: PTFE, commonly known by the trademarked name Teflon, is a highly durable and corrosion-resistant insulator. It is useful for cable jackets.
  • Perfluoroalkoxy (PFA): PFA is a flexible insulator with four times the dielectric strength of PTFE. Thanks to its corrosion resistance, PFA can be used outdoors and even near the ocean.
  • Rubber: Although rubber is often the first material people associate with insulation, it is no longer the first choice in most applications. Synthetic plastics tend to offer better overall performance and more flexibility at a competitive price. 

#4 What are some of the applications of electrical insulating materials?

The applications of electrical insulation are nearly as diverse as the applications of electricity itself. However, some of the most common include:

  • Cables and Power Lines: Cables of all sizes and voltages require protective coatings to separate conductors and prevent current from leaking. Bushings made from porcelain, glass, or polymers are suitable insulators for this high-voltage application.
  • Circuit Boards and Electronics: Most modern electronics are based on printed circuit boards (PCBs). The surface of PCBs insulates while etched pathways conduct electricity between mounted components.
  • Power Systems: Both solid and liquid insulation are necessary to protect users of power systems, including transformers, stabilizers, generators, and circuit breakers of all sizes. 
  • PPE and Employee Safety: Insulation is a key component of PPE, including gloves and boots, which protect the highly conductive human body from sustaining electrical shocks. For the same reason, rubber mats may be positioned below control panels to protect employees that must interact with high-voltage systems.
  • Insulation Tapes: Commonly made from PVC, electrical tapes effectively insulate live components for safety purposes. While it is usually used for temporary repairs, it can create a long-lasting seal against currents.

#5 "Is electrical insulation required for my application?"

Electrical insulation is a necessary component for virtually all electrical systems, including everyday electronics and high-voltage power stations. If your application involves live conductors of any kind, you must incorporate appropriate insulation to protect equipment and employees from stray current.

Some industries that are more likely to require insulation solutions include:

  • Automotive and transportation
  • Computers and peripherals
  • Consumer products and electronics
  • Conventional and uninterruptible power supplies
  • Electrical and power distribution systems
  • Home appliances
  • Lighting
  • Medical equipment
  • Telecommunications equipment

#6 "What are the primary components used for electrical insulation?"

Effective insulation depends on barriers and insulation materials to block current. These components should be chosen and shaped based on the electrical system in question. 

Some additional components that may be used to block electrical flow include:

  • Washers
  • Gaskets
  • Spacers
  • Bushings
  • Coil form bobbins
  • Arc chutes
  • Brush plate holders

#7 "How are components made or fabricated for electrical insulation?"

Most electrical insulation components are made from thin sheets of non-metals, including various types of vinyl, plastics, rubbers, and composite materials. Fabrication for these materials typically includes the following processes designed to cut precise shapes to tight tolerances:

  • Laser Cutting: Laser cutting uses directed high-energy beams to slice through sheets of material. This process is among the most precise options for cutting non-metals, and yet it remains cost-effective and highly efficient.
  • Die-Cutting & Stamping: Die-cutting and stamping both use high pressure and custom tooling to form sheets into custom shapes. Although these processes require a minimal up-front investment in tooling, they are a cost-efficient means of producing insulators in high volumes. A key benefit of die-cutting and stamping is their excellent repeatability, ensuring clients receive truly consistent results at any volume.

Other possible techniques include digital cutting, CNC turning and milling, and shearing or slitting, depending on the application’s requirements.

#8 "What happens when electrical insulation fails? Or if my device does not have it?"

All insulation eventually breaks down, losing its resistivity and acting more like a conductor. As this happens, systems begin to experience increased heat and loss of efficiency until the insulation is replaced or catastrophic failure occurs.

When insulation completely degrades, the outcome can be disastrous. At a minimum, you can expect heat damage and short circuits. At worst, failed insulation can lead to explosions at the failure point.

To prevent catastrophic equipment failure, it’s critical to install, inspect, and maintain the right insulation for your application.

#9 "How can ESPE Manufacturing help me?"

ESPE Manufacturing is a leading supplier of electrical insulation and custom non-metal components. We partner with our clients to develop fully-customized manufacturing solutions, no matter how complex the specifications. Whether you need raw insulation material or a high-volume run of formed components, we can help.

We are experts in precision fabrication and our 30,000 square-foot facility is stocked with state-of-the-art equipment to enable:

  • Die-cutting
  • Stamping
  • Laser cutting
  • Digital cutting
  • CNC milling
  • CNC turning
  • Shearing and slitting

We apply these capabilities to a wide range of performance materials. For every project, we consult carefully with clients to choose the ideal material for their performance needs and environmental constraints. Our preferred materials include:

  • ITW Formex: Formex is a flame-retardant polymer that combines polypropylene and polycarbonate. It is ideal for insulation and shielding applications.
  • Nomex: Nomex is a paper-thin insulator used in applications like mobile phones, battery packs, and televisions.
  • Fishpaper/Vulcanized Fiber: This cellulose-based material is extremely lightweight and features superior heat and cold resistance compared to other insulators.

We also work with an extensive selection of non-metal materials to ensure we provide the right solution for your application.

Specifically, our custom-part fabrication capabilities include:

These services are available for volumes ranging from prototype runs to high-volume production runs exceeding 100,000 components. Our services are available to clients of all sizes and at every stage of the design process.  

Learn How ESPE Manufacturing Can Help You

Electrical insulation is a complex topic, and it’s essential to get right. That’s why you need a knowledgeable partner like ESPE, where we have over 70 years of experience in custom manufacturing. Contact us or request a quote today to learn how we can help with your electrical insulator needs.