Point load

A point load is the concentrated force arriving at a single structural attachment. It is what a venue publishes limits for, because a roof structure does not experience a rig as a total weight spread evenly; it experiences a series of concentrated forces at specific nodes.

This is why the first question from a venue is never how much the rig weighs. It is how much lands on each point, and where those points are. A six thousand pound rig on twelve well-distributed points may be straightforward where the same rig on four points is not permitted at all.

Two things raise a point load beyond the obvious arithmetic. The first is uneven distribution: a motor nearer a heavy cluster takes more than its share, and a truss with an LED wall at one end does not divide its load equally between its two ends. The second is dynamic force. Starting and stopping a lift, or a load swinging as it is positioned, briefly delivers more than the static weight, which is why the static sum is a floor rather than an answer.

Bridling changes point loads substantially and almost always upwards, which is the reason a bridle is calculated rather than estimated by eye.

Staging and rigging — owned inventory, our own crew, and a site survey before anything is specified.

• Rigging point One place where a load is attached to the building — counted and rated individually, because the building cares where the weight is, not how much is in the room.
• Bridle Two legs run from separate attachments to a common point, used when the hang position does not line up with a beam — and a geometry that multiplies tension rather than sharing it.
• Working load limit (WLL) The most a piece of rigging hardware may be asked to carry — typically a fifth of what it would take to break it, and halved again by convention for anything over people.