Counterweight Blocking
Counterweight blocking is the practice of using a physical block, stop, crib, restraint, or equivalent engineered measure to prevent a counterweight from moving, falling, swinging, or shearing into a hazardous position during installation, maintenance, repair, or operation. It is a key control for crush, pinch, struck-by, or entrapment hazards on shop floors, ensuring worker safety by physically restraining counterweights.
On a manufacturing or shop floor, counterweight blocking is applied wherever a counterweight could create a crush, pinch, struck-by, or entrapment hazard if it shifts unexpectedly. Typical examples include serviced crane counterweight assemblies, suspended platform counterweights, hoist/press balancing systems, and maintenance tasks where the counterweight must be mechanically secured before workers enter the danger zone. Before maintenance, workers isolate energy and install positive blocking to prevent movement into the work envelope. For tower cranes, counterweights must match OEM or professional engineer specifications, with each element accurately weighed and durably marked. Where counterweights are above access areas or not fully enclosed, additional restraint or guarding is used to prevent collapse or falling movement.
- Improvised blocking: using wood blocks, wedges, or loose cribbing that are not sized or secured for the actual counterweight load or motion path, violating requirements for blocking to be sized and used so support load does not exceed bearing capacity.
- Relying on procedure instead of physical restraint: assuming lockout, signage, or radio communication is enough, but the counterweight remains free to move, whereas physical prevention of hazardous movement is the key control.
- Unverified or altered counterweights: incorrect counterweight mass, missing markings, substitution of non-OEM parts, or easy removal/tampering, which must be avoided by ensuring counterweights are OEM- or engineer-specified and each element accurately weighed and marked.
Is 'counterweight blocking' a standalone WorkSafeBC term?
No. WorkSafeBC generally regulates the hazard through provisions on counterweights, blocking/shoring/cribbing, guarding, and movement control rather than using 'counterweight blocking' as a formal standalone defined term.
When is physical blocking required instead of procedural control?
When a counterweight could create a crush, swing, shear, or drop hazard, physical restraint is the defensible control because WorkSafeBC requires hazard elimination or effective control of movement, not just warning practices.
What document most directly governs tower crane counterweights in B.C.?
WorkSafeBC OHS Regulation Part 14, section 14.80, which requires counterweights and ballasts on tower cranes to be OEM- or professional-engineer-specified and individually weighed/marked.