IP is an abbreviation for a rating called Ingress Protection. What this rating tells you is the level of protection that a laser level, theodolite, automatic level, etc has from the elements. On a construction site, an instrument can be subject to dust, dirt, grime, and water from a variety of sources. How well is your instrument protected from all of these solid and liquid substances that will ruin an expensive piece of equipment?

The IP rating is usually made up of two numbers. The first number signifies the instrument's level of protection from solid objects or substances. The second number signifies the instruments level of protection from liquids or water:

Below are two charts listing the various degrees of protection that an instrument can have.

The IP rating can be very important when the instrument's primary use is outdoors. Good examples of this are theodolites, automatic levels and rotary laser levels. You'll see many automatic levels and rotary lasers with IP ratings of 54. These instruments are protected against most dust getting into and from water splashing onto them during their daily operation.

Topcon theodolites often carry an IP rating of 66. This rating means that these Topcon theodolites are totally protected from dust and from getting temporarily flooded with water. Many of the Johnson Level Rotary Lasers also have a IP of 66. Pacific Laser Systems rotary lasers often have a rating of IP65. Two Agatec rotary lasers, the LT200 and LT300, have one of the highest IPs of any instrument of this type, 67. These lasers can be immersed in water up to one meter in depth.

If you will be working in the weather or on a dusty construction site with your instrument, knowing its IP rating will help you to be aware of how well it can handle the water and dirt.