Bosch EVF-1122S/126 EVF-1122S/126-PIB User Manual

Electro-Voice EVF/EVH User Manual

37

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.

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.