Comprehensive Guide to Busbar Insulation Materials and Methods

Proper insulation of busbars is critical for safe and reliable operation of power distribution systems. Bare busbars present the risks of shock, arcing, short circuiting and energy loss. Applying specialized insulation materials and techniques mitigates these hazards.

GRL prepared this guide to provide electrical engineers, contractors and maintenance teams a comprehensive overview of busbar insulation. It covers insulation materials, application methods, testing procedures, repair techniques and more. Contact us if you have any questions.

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Understanding Busbar Insulation

Busbar insulation refers to protective covering applied to busbars in switchgear, panelboards and other electrical distribution components. It serves several key functions:

Safety – Insulated busbars prevent user contact with exposed live conductors, reducing risk of electric shock, burns and electrocution.

Reliability – Insulation protects against short circuiting between bus phases or to ground. This prevents system faults, tripping and downtime.

Noise Reduction – Insulated busbars dampen buzzing and humming noise from current flow. This creates quieter power distribution equipment.

Corrosion Protection – Insulation forms a barrier between the bare bus and environmental contaminants. This improves longevity and reliability.

With rising voltage levels and decreasing busbar spacing, proper insulation becomes ever more critical in modern systems. Advancements in insulation materials and application methods now allow superior busbar protection across diverse electrical environments.

Busbar Insulation Materials

Various insulation materials offer different performance, cost and application trade-offs. Common options include:

Epoxy Coatings

Epoxy is the most popular insulation choice for coating busbars. The two-part liquid is applied via dipping, spraying or brushing. As it cures, the epoxy forms a durable insulation layer with excellent adhesion strength.

Benefits of epoxy busbar coatings include:

  • Thin layer provides insulation without much bulk
  • Conforms evenly to complex busbar shapes
  • Does not tear or crack over time
  • Excellent dielectric strength
  • Withstands high temperatures
  • Good chemical and moisture resistance

Epoxy does have a limited pot life when mixed. So the coating process requires some expertise. Overall, epoxy strikes the best balance between performance, cost and ease of application.

Insulating Tapes and Wraps

Specialized tapes using materials like PTFE and polyimide can be wrapped around busbars to add insulation. Multiple layers build up the needed dielectric strength.

Tapes offer benefits like:

  • Flexibility to insulate complex or irregular shapes
  • No curing time required
  • Easy installation in the field
  • Wide operating temperature range
  • Outer jacketing resists abrasion and chemicals

However, tape wrapping is labor intensive. And adhesion can weaken over time in vibrating environments. Tapes work best for insulating busbar joints or small touch-up repairs.

Sleeving and Tubing

Sliding insulating sleeves and tubes over busbars provides protection with the least handling. Common materials include silicone rubber, fiberglass and various polymers.

Sleeving advantages:

  • Super quick and easy installation
  • Clean look with no drips or mess
  • Allows visual busbar inspection
  • Options for high heat or flexibility

The main limitation is fitting sleeves over bus connections and hardware. Custom molded sleeves can accommodate more complex busbar arrangements.

Insulating Boots and Covers

Boots or covers made of silicone or other polymers slip over busbar ends to insulate connections, splices and joints. Some main benefits:

  • Protect vulnerable connection points
  • Prevent arcing or shorting
  • Easy to add insulation during or post-installation
  • Allen key access for bolted covers
  • Reusable for maintenance access

However, covers can obstruct busbar inspection. And slipped-on boots may not seal effectively without adhesive. These options best complement other insulation methods.

Other Insulating Materials

Beyond the main options above, other niche busbar insulation materials include:

  • Mylar or polyester film wraps
  • Fiberboard barriers
  • Thermoset plastic shielding
  • Rigid rubberized covers
  • Shrink tubing
  • Ceramic beads

These satisfy special requirements like high voltage protection or increased spacing between bus phases.

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Busbar Insulation Application Methods

Proper application and installation technique ensures insulation materials perform to their full potential. Key factors include:

Pre- vs Post-Installation

Busbars may be insulated either before or after installation into electrical equipment:

  • Pre-installation – Coating, wrapping or sleeving busbars at the factory provides protection from the outset. Doing so also insulates joints and connections. But it can hamper visual inspection later.
  • Post-installation – Insulating bus after installation allows maintenance access to connections. But bus joints may remain exposed. And workspace may be tight inside equipment.

In practice, a combination works best. Bulk insulation prior to installation along with supplementary joint boots and covers after installation gives optimal coverage.

Insulating Busbar Joints

Busbar joints require special attention during insulation. These high-risk points have exposed metal-to-metal contact between sections. Direct epoxy coating or insulating covers/boots reliably protect these joints.

For large equipment, joint covers may have removable sections or allen key access ports. This enables later access to bolted connections for maintenance.

Epoxy Dipping Process

When coating busbars with epoxy, a dipping process ensures optimal insulation:

  1. Busbars are hung on racks and cleaned thoroughly
  2. Sections are dipped into or sprayed with two-part epoxy
  3. Excess epoxy drips off while the rack rotates
  4. The coated bus is cured in an oven
  5. Coating thickness and dielectric strength are tested

Automated epoxy dip systems efficiently insulate large production runs of busbar with precision.

Shielding and Barrier Methods

Insulating shields or covers made of plastic, rubber or composites can be fastened around bare bus sections. Barriers placed between bus phases add protection against arcing or shorting.

Shielding methods are quick and allow visual inspection. However, manual assembly and numerous fasteners may be required. Proper spacing gaps must be maintained as well.

Testing and Standards for Insulated Busbars

To validate insulation materials and application methods, busbars undergo a battery of type tests:

Dielectric Testing

Insulation withstand voltage is proven by applying escalating test voltages without dielectric breakdown. Puncture testing then stresses the insulation beyond limits to verify robustness.

Temperature Cycling

Temperature extremes between -40°C to +115°C test insulation resilience during expansion and contraction cycles.

Mechanical Stress

Insulated busbars undergo vibration, shock and abuse testing to ensure insulation remains intact despite intense mechanical forces.

Chemical Exposure

Chemicals like oils, greases and solvents applied to insulation simulate years of exposure to confirm durability.

Busbars passing certification tests comply with different national and international standards. This includes IEC, IEEE, BS, JIS and others.

Maintenance of Insulated Busbars

To maximize insulation lifespan, scheduled inspection and maintenance procedures are recommended:

  • Visual inspection for cracks, burns or damage during routine equipment servicing
  • Checking insulation adhesion strength
  • Monitoring insulation resistance and dielectric values
  • Replacing worn or damaged insulating boots/covers
  • Removal of dust, grime and contaminants
  • Repairing insulation defects immediately to prevent arcing

With proper maintenance, quality busbar insulation should last upwards of 15-20 years in most electrical environments.

Repairing Damaged Busbar Insulation

Should insulation become compromised, timely repairs are critical to avoid equipment failure.

For minor damage, adding insulating tape, epoxy or covers/boots remedies the defects. More extensive damage may require removing and recoating large busbar sections.

During repairs:

  • Remove damaged insulation completely
  • Clean busbars to bare metal
  • Mask areas not being repaired
  • Reapply insulation using original specifications
  • Allow proper cure time before reenergizing

Seeking manufacturer guidance for approved repair methods is advised.

Getting Insulated Busbars for Your Project

If you require insulated busbars for an upcoming project, here are key considerations:

Selecting a Busbar Insulation Partner

Choose a vendor with expertise in materials, applications, testing and certifications. Capabilities like automated epoxy dip coating ensure quality results. Opt for a supplier involved from design through to production.

Defining Technical Requirements

Specify important parameters like busbar sizes, operating voltages, spacing, environmental conditions, applicable standards and expected lifespan. This ensures the vendor applies suitable insulation methods.

Requesting Samples and Testing Data

Ask potential suppliers to provide insulated busbar samples that represent their workmanship. Review test reports to validate the samples meet your technical requirements.

Comparing Solution Cost Effectiveness

Consider upfront material and application costs along with total lifecycle savings from enhanced safety, reduced maintenance and prevented downtime. The ideal solution balances cost, lead time and performance.

Get in touch with experienced busbar insulation partners to discuss your unique project needs today.

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Frequently Asked Questions

What is busbar insulation?

Busbar insulation refers to protective materials like epoxy, sleeves and shields applied to busbars in switchgear and distribution boards to prevent shorting, arcing, shocks and corrosion.

Why is busbar insulation important?

Insulation improves safety and reliability. Bare busbars risk electrocution from contact. Insulation prevents short circuits and reduces noise. It also protects against corrosion over decades of operation.

What are the different types of busbar insulation?

Common insulation options include epoxy coating, sleeves, insulating boots, shielding, wraps using tape or polymer films, and barriers between bus phases. Each has pros and cons.

What materials are used for busbar insulation?

Typical materials are epoxy, silicone rubber, PTFE tape, fiberglass sleeving, polyimide film, thermoset plastics, and various plastic or polymer composites. The material depends on voltage, environment, space and cost considerations.

How is epoxy used for insulating busbars?

Two-part epoxy is applied via dipping, spraying or brushing. It cures into a durable insulation coating. Automated dipping ensures optimal thickness and adhesion. Epoxy is the most popular busbar insulation choice.

What are busbar insulating covers and shields?

Covers and shields made of silicone or polymers mount over bare bus sections or joints. Some have removable access ports. Shielding between bus phases helps prevent arcing. They complement other insulation methods.

How do you install busbar insulation?

Application methods include automated epoxy dip coating, manual taping/wrapping, slipping on sleeves or covers, and fastening insulating shields. Combining factory insulation with post-installation insulation of joints provides full coverage.

What are the standards for insulated busbars?

Insulated busbars must pass testing to certify insulation dielectric strength, temperature rating, and resistance to mechanical/chemical stresses. Common standards include IEC, IEEE, JIS and BS.

How do you test the insulation on busbars?

Testing involves applying escalating voltages to prove dielectric strength without breakdown, temperature cycling from -40°C to +115°C, and subjecting insulation to mechanical forces and chemicals to validate durability.

Can you insulate busbars after installation?

Yes, bus joints, connections and clearances can be insulated after installation using tapes, sleeves, covers or epoxy. But access within equipment may be limited. Combining factory and post-installation insulation is optimal.

How much does busbar insulation cost?

The cost depends on insulation materials, application methods and production volumes. Automated processes like epoxy dip coating offer cost efficiency at scale. Insulation added post-installation has higher labor costs.

Does busbar insulation increase current rating?

Not inherently. But insulating busbars enables tighter spacing between phases since arcing risks are reduced. Denser busbar assembly then allows higher rated current capacity by expanding the cross-sectional area.

What causes busbar insulation failure?

Factors like prolonged overloads, corrosion, vibration, thermal cycling, chemicals, UV exposure, abrasion, improper application, manufacturing defects or maintenance damage can compromise insulation over time.

How long does busbar insulation last?

With proper materials, application and maintenance, quality busbar insulation should last 15-20 years. Some critical factors affecting lifespan include operating temperatures, mechanical stresses and chemical exposure.

Is busbar insulation required by code?

Certain high voltage busbars above 600VAC must be insulated per National Electrical Code. But even below 600VAC, insulation improves safety and is recommended. Applicable codes depend on voltage class and location.

Does busbar insulation reduce noise?

Yes, insulating busbars helps muffle buzzing, humming and vibration noises from alternating current flow through bus sections and joints. This significantly reduces audible noise from switchgear and distribution equipment.

Can you repair damaged busbar insulation?

Yes, minor insulation damage can be repaired by patching with tape, epoxy or insulating covers. More extensive damage may require removing old insulation and recoating busbar sections using original specifications.

How thick should busbar insulation be?

Standard epoxy coatings range from 200-600 microns. Insulation thickness specified depends on the dielectric rating and voltage required. More layers increase insulation strength but add bulk.

What is the dielectric strength of busbar insulation?

Dielectric strength indicates how much voltage insulation can withstand without breakdown. Epoxy busbar coatings offer 15-25 kV/mm. Tapes range 5-12 kV/mm. Higher ratings provide greater protection.

How do you maintain insulated busbars?

Maintenance involves visual inspection for damage, testing insulation adhesion and electrical properties, cleaning contaminants, replacing worn parts, and repairing defects immediately. This maximizes insulation lifespan.

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