5 Ways to Avoid Static Electricity Hazards in a Lab

1. Bonding

Bonding is a safety technique that prevents static sparks by electrically connecting two or more conductive objects so they share the same electrical potential. It is widely used when transferring flammable liquids, because friction between liquid and container creates static charge. When containers are bonded, any charge difference quickly equalizes through the conductive link, eliminating any spark potential between them.

• Purpose: Bonding equalizes charges. For example, if a metal drum and a metal pail are both bonded with a clip and cable, any static charge on one will flow to the other. This ensures there is no voltage difference between them that could spark during a transfer.
• How it works: Use a bonding cable or strap with metal alligator clamps on each end. Attach one clamp to the dispensing container, such as a metal drum or valve outlet, and the other clamp to the receiving container or a metal funnel. This creates a conductive path between them.
• When to use: Always bond before starting any transfer of flammable or combustible liquids from one container to another. Keep the bond in place until after the transfer is complete.

Pouring a flammable solvent from a large drum into a metal bucket. By attaching one clamp to the drum and one to the bucket, the two containers share the same electrical potential. Any static generated by the flowing liquid is instantly neutralized through the bond, so no spark can jump between the drum and bucket during the pouring process.

Steps for bonding containers:

• Identify conductive points on both containers, such as metal drums, tanks, or pipe fittings.
• Use a static bonding cable or braided copper strap with metal alligator clamps on each end.
• Attach one clamp to the dispensing container, such as the metal drum or valve outlet.
• Attach the other clamp to the receiving container or a metal funnel inserted into it.
• Ensure each clamp has solid metal-to-metal contact and the cable is tight.
• Only begin the transfer after the bond is securely in place.
• Keep the bond connected until the transfer is finished and the containers are stationary.

2. Grounding

Grounding, also known as earthing, directs static charge safely into the earth, keeping equipment and containers at zero electrical potential. In a lab, grounding prevents any build-up of static by providing a path for charge to flow away. For example, grounding a metal drum or lab bench ensures that any static charge is continuously drained into earth, preventing sparks.

• Purpose: Grounding provides a zero-volt reference. By connecting a conductive object to earth, any static charge on it flows into the ground so the equipment cannot hold a significant charge.
• How it works: Attach a grounding conductor from the equipment or container to a verified earth point. The conductor is typically a copper wire, often insulated green or bare. Run the wire to a known ground point, such as a grounded outlet, a bonded plumbing pipe, or a grounding rod. The conductor provides a low-resistance path for any static to escape safely.

Typical items to ground:

• Flammable liquid storage cabinets especially when flammable liquids are dispensed.
• Metal drums, tanks, or piping that hold flammable or combustible liquids.
• Metal lab benches, shelves, and static-dissipative floor mats.
• Any conductive equipment where static may accumulate, for example mixers, conveyor chutes, balances, or similar equipment.

Many safety cabinets have a grounding lug or bolt on the exterior. If present, attach a copper grounding wire from this lug to earth. If no lug is provided, clamp the wire to a metal shelf or vent inside the cabinet. Run the other end of the wire to a true earth ground, such as the building's ground bus or a ground rod. This ensures any static in the cabinet dissipates to earth rather than building up near stored solvents.

Key practices:

• Use heavy-gauge, low-resistance grounding wire and ensure all connections are tight and clean.
• Do not attach to pipes or conduit unless they are proven to be an earth ground; never use a fire sprinkler line as a ground.
• Regularly verify grounding with an ohmmeter; a proper ground should show very low resistance near zero ohms.
• Always keep flammable equipment grounded when in use. For example, when transferring liquids, connect the container to ground first, then bond the containers together.

3. ESD Workbench

An ESD (Electrostatic Discharge) workbench is a specially designed laboratory workstation that prevents static electricity buildup on both equipment and personnel. It achieves this by ensuring that all surfaces, tools, and people in the workstation are at the same electrical potential. In practice, this means providing conductive surfaces and grounding paths so that any static charge is immediately dissipated to earth rather than accumulating or discharging unexpectedly.

• Anti-static work surface: The bench top is covered with a static-dissipative mat, typically vinyl or rubber, that is grounded. Any charge on objects placed on the mat slowly dissipates through the mat into the ground.
• Wrist straps and cords: Technicians wear an ESD wrist strap connected to the bench ground. The coiled cord from the wrist strap plugs into the bench or a common ground point. This safely conducts any static charge on the person to the ground.
• Foot grounding: For operators who stand, an anti-static floor mat or conductive floor can be used. Some setups include a heel strap that the person wears. This ensures a standing operator is also grounded through the mat.
• Grounding jacks and common ground: The workbench provides dedicated grounding jacks (often banana-jack connectors). All dissipative mats, wrist straps, and foot straps connect to a single common grounding bus. This unifies all components and personnel at the same potential.
• Ionizer: An ionizing bar or blower may be installed above or on the bench. It emits a balanced stream of positive and negative ions into the air, neutralizing any charge on insulating surfaces that the grounding system cannot directly remove.
• Other features: ESD workstations often include conductive metal chairs (with conductive wheels), static-dissipative containers or bins for components, and ground-strap monitors. These monitors check the resistance of the wrist-strap circuit and alert if a strap or ground connection fails. All these elements work together to prevent uncontrolled electrostatic discharge.

4. Ionization and Environmental Controls

Even with proper bonding and grounding, static charge can accumulate on insulating surfaces or in very dry air. To address this, labs use ionizers and control environmental conditions like humidity. These methods prevent charge build-up or neutralize any charge quickly.

• Ionizers: Ionizing devices emit a balanced stream of positive and negative ions. Placed above or near a workstation, an ionizer neutralizes any charge on insulating surfaces. For example, blowing ionized air onto a plastic container or glassware will remove its static. Ionizers are commonly used in fume hoods or on benches where sensitive electronic or optical components are handled. By eliminating charge on insulating objects, an ionizer prevents sparks even if the object cannot be directly grounded.
• Humidity Control: Static electricity is worse in dry air. Maintaining a relative humidity around 40%–60% significantly reduces static buildup. Moist air allows small charges to leak away through moisture on surfaces. Use humidifiers or the lab's HVAC system to avoid extremely dry conditions. For instance, if the lab drops to 20% relative humidity in winter, adding moisture to reach 50% RH can prevent quick charge buildup on clothing or plastic tubing.
• Environmental measures: Choose laboratory furnishings and layout to minimize static. Avoid carpeting or vinyl floors in critical areas; instead use static-dissipative mats or ESD-safe tiles. Limit the use of insulating materials: for plastic or acrylic equipment, apply anti-static coatings or clean it regularly with conductive wipes. Keep all surfaces and tools clean-dust and debris are insulators that hold charge and should be cleaned off. Do not drag chairs or carts across the floor; instead, use chairs and carts with conductive wheels. These steps help prevent static from building up on equipment and floors.
• Additional controls: In some labs, controlling temperature along with humidity maintains stable conditions. Special conductive flooring or embedded grounding plates under benches can improve grounding. Portable ESD monitors and static field meters can be used to verify that ionizers and humidity controls are effectively neutralizing static in the workspace.

5. Anti-Static Materials and Clothing

Using static-dissipative materials and wearing appropriate gear helps prevent charge buildup on people and lab items. These measures reduce triboelectric charging at the source and keep everyone and everything at safe potential.

• ESD Lab Wear: Use anti-static lab coats, jackets, or smocks made of static-dissipative fabric. These garments incorporate conductive fibers that spread charge and allow it to bleed off (some even have snap cuffs for a grounding cord). If specialized ESD clothing is unavailable, wear a cotton lab coat instead of polyester; cotton generates much less static when rubbed.
• Footwear and Floor Mats: Wear ESD-safe shoes or use heel straps on a conductive floor mat. Many labs provide static-dissipative shoe covers or special ESD shoes that connect through the sole to the ground mat. As long as a person stands on the mat, any charge on their body continuously dissipates to earth. Place anti-static mats at benches and doorways so people are grounded as they work or walk.
• Gloves and Tools: Use static-dissipative gloves and implements to prevent charge accumulation. For example, anti-static nitrile or carbon-impregnated gloves stop charge on your hands when handling plastic parts. Use metal or conductive tools (tongs, spatulas, funnels) instead of plastic ones. These provide a path for any charge, allowing it to flow safely to the grounded bench or person.
• Containers and Packaging: Use conductive or static-dissipative containers for chemicals, powders, and components. Store solvents on grounded metal shelves and keep electronic parts in static-shielding bags or conductive bins. Avoid plastic jug liners or ungrounded glass; even small vials can be carried on a grounded metal tray. Using the right containers prevents static from accumulating on stored materials.
• Minimize Insulators: Wherever possible, replace insulating materials with conductive ones. Use metal benches, racks, and tools instead of plastic. If plastic equipment is necessary, apply an anti-static coating or wipe it with a conductive cleaning solution regularly. Keep all surfaces and tools clean-dust and lint are insulators that hold charge and should be cleaned off. These steps stop charge from building up on equipment.
• Other measures: Ground conductive lab furniture and equipment whenever possible. Use chairs with conductive casters and static-dissipative mats under seating. Employ anti-static brushes or ESD vacuums when cleaning lab apparatus. By combining the proper gear and materials, personnel ensure that neither they nor any objects become unexpectedly charged.