Electro-Voice EVF/EVH EVF-1151S - Manual (Page 37)

Electro-Voice EVF/EVH User Manual 37
6.0 Rigging-Strength Ratings and Safety Factors
6.1 Working Load Limit and Safety-Factor Definitions
The structural ratings for all of the EVF and EVH rigging components and complete loudspeaker sys-
tems are based on test results in which parts were stressed to failure. Manufacturers typically present the
structural-strength ratings of mechanical components or systems as either the Working Load Limit (WLL)
or the ultimate-break strength. Electro-Voice chooses to present the structural-load ratings of the EVF and
EVH loudspeaker systems as the WLL. The WLL rating represents the maximum load that should ever be
applied to a mechanical component or system.
THE USER SHOULD NEVER APPLy A LOAD THAT EXCEEDS THE WLL OF ANy OF THE
RIGGING COMPONENTS OR COMPLETE LOUDSPEAKER SySTEMS DESCRIBED IN
THIS MANUAL.
The WLL for the EVF and EVH rigging components and complete loudspeaker systems described in this
manual are based on a minimum 8:1 safety factor. The safety factor is defined as the ratio of the ultimate-
break strength divided by the WLL, where the ultimate-break strength represents the force at which a
part will structurally fail. For example, if a part has a WLL of 1,000 lb (454 kg), it would not structurally fail
until a force of at least 8,000 lb (3,629 kg) was applied, based on an 8:1 safety factor. However, the user
should never apply a load to that part that exceeds 1,000 lb (454 kg). The safety factor provides a margin
of safety above the WLL to accommodate normal dynamic loading and normal wear.
CAUTIONS for Working Load Limits and Safety Factors
The WLL defined by the manufacturer of any rigging component should never be exceeded. Electro-Voice
bases the WLL of its EVF and EVH products on a minimum of an 8:1 safety factor. Other manufacturers
of rigging components may base their WLL on safety factors other than 8:1. For example, 5:1 safety fac-
tors are fairly common among rigging manufacturers because many regulatory agencies call for a minimum
safety factor of 5:1.
When an EVF and EVH loudspeaker system is installed where local regulations only require a safety factor
of 5:1, Electro-Voice insists that the WLL of the EVF and EVH rigging never be exceeded and that an 8:1
safety factor be maintained for the EVF and EVH loudspeakers.
The user is cautioned that some local regulations may require safety factors higher than 8:1. In that cir-
cumstance, Electro-Voice insists that the user maintain the higher safety factor as required by the local
regulations throughout the entire EVF and EVH installation. It is the responsibility of the user to make sure
that any EVF and EVH installation meets all applicable local, state or federal safety regulations.