Static Grounding Bonding
What electrical characteristics define an effective static grounding path?
An effective static grounding path must have low impedance, sufficient ampacity to conduct fault currents and static discharge, and low resistance to earth (industry target ≤10 Ω). The Canadian Electrical Code requires a grounding path of low impedance and sufficient ampacity to prevent harmful voltages.
How does bonding differ when controlling static hazards vs shock hazards?
For static hazards, bonding equalizes electrostatic potential between conductive objects to prevent sparks, and grounding dissipates charge to earth. For shock hazards, bonding permanently joins non-current-carrying metal parts to create equipotential surfaces and a fault path, while grounding connects to safety ground to clear fault currents and limit touch voltages.
Why is continuous bonding required during transfer, and what does 'firm contact' mean?
Continuous bonding ensures no gap in equipotential occurs while fluid flow generates static charge; even brief disconnections can cause spark risk. 'Firm contact' means containers are in direct metal contact or secured with robust bonding conductors/clamps that maintain electrically sound connections, as per WorkSafeBC Part 23.
Static grounding and bonding are control measures that connect conductive equipment together and to earth to safely dissipate static electricity, prevent ignition of flammable vapours/dusts, and maintain equipotential between objects during industrial operations such as dispensing, transferring, and mixing flammables. Bonding equalizes charge between objects, while grounding provides a low-resistance path to earth to dissipate charge.
On the shop floor, static grounding and bonding are applied during transfer of flammable liquids (e.g., solvents, fuels) between drums, totes, or tanks, and during handling of combustible dusts. Typical hardware includes static grounding clamps with serrated points for metal-to-metal contact, bonding conductors (e.g., No. 6 copper wire), and a verified ground point (e.g., grounding electrode) with resistance ≤10 Ω. Procedures require attaching clamps before transfer, maintaining continuous bonding throughout, and disconnecting only after vapours dissipate. WorkSafeBC mandates bonding and grounding under Part 5 §5.27 and Part 23 §23.6 for all such operations.
Bonding without effective grounding: Containers bonded to each other but not to earth leave the system at elevated potential relative to ground, risking discharge to a worker or grounded object.
Poor clamp contact and degraded conductors: Clamps on painted, rusted, or dirty surfaces fail to achieve metal-to-metal contact; corroded or undersized cables increase resistance, making the system nonfunctional.
Interruption of bond/ground during active transfer: Disconnecting clamps while transfer is underway allows static charge to accumulate and cause a spark, violating WorkSafeBC's requirement for continuous bonding.