Campbell Scientific CR3000 Micrologger - Manual (Page 93)

Section 7. Installation
93
In laboratory applications, locating a stable earth ground is challenging, but still
necessary. In older buildings, new ac receptacles on older ac wiring may indicate
that a safety ground exists when, in fact, the socket is not grounded. If a safety
ground does exist, good practice dictates the verification that it carries no current.
If the integrity of the ac power ground is in doubt, also ground the system through
the building plumbing, or use another verified connection to earth ground.
Figure 33: Schematic of grounds
7.5.1.1 Lightning Protection
The most common and destructive ESDs are primary and secondary lightning
strikes. Primary lightning strikes hit instrumentation directly. Secondary strikes
induce voltage in power lines or wires connected to instrumentation. While
elaborate, expensive, and nearly infallible lightning protection systems are on the
market, Campbell Scientific, for many years, has employed a simple and
inexpensive design that protects most systems in most circumstances. It is,
however, not infallible.