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en | Rigging strength ratings and safety factors
EVC Variable-Intensity Loudspeakers
2019-10 | 04 | F.01U.378.116
Installation manual
Electro-Voice
5
Rigging strength ratings and safety factors
Working load limit and safety-factor definitions
The structural ratings for all EVC rigging components and loudspeaker systems 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 loudspeaker systems as the WLL. The WLL rating represents the maximum load
that should ever be applied to a mechanical component or system.
!
Warning!
Never exceed the limitations or maximum recommended working load for Electro-Voice
loudspeakers.
Disregarding this warning could result in serious injury or death.
The WLL for the rigging components and loudspeaker systems described in this manual is
calculated with a 10:1 safety factor, which exceeds the minimum 8:1 safety factor normally
specified by Electro-Voice. 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 100 lb (45.4 kg), it would not
structurally fail until a force of at least 1,000 lb (453.6 kg) was applied, based on a 10:1 safety
factor. However, the user should never apply a load to that part that exceeds 100 lb (45.4 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.
Other manufacturers of rigging components may base their WLL on safety factors other than
10:1. For example, 5:1 safety factors are fairly common among rigging manufacturers because
many regulatory agencies call for a minimum safety factor of 5:1.
When an EV loudspeaker system is installed where local regulations only require a safety
factor of 5:1, Electro-Voice insists that the WLL of the loudspeaker rigging never be exceeded
and that an 10:1 safety factor be maintained.
The user is cautioned that some local regulations may require safety factors higher than 10:1.
In those circumstances, Electro-Voice insists that the user maintain the higher safety factor as
required by the local regulations throughout the entire loudspeaker installation. It is the
responsibility of the user to make sure that any loudspeaker installation meets all applicable
local, state or federal safety regulations.
Recommended practice for eyebolts
Eyebolts can be used to suspend individual loudspeakers when attached through the integral
M10 attachment points. It is a good idea to orient the suspending cable so that it hangs within
30° of the straight-up position in the plane of pull (left illustration), and within 15° against the
plane of pull (right illustration).
