Measurement Computing PCM-DAS16D/12 - Manual (Page 18)

NOTE
Relying on the earth prong of a 120VAC for signal ground
connections is not advised.. Different ground plugs may have
large and potentially even dangerous voltage differentials.
Remember that the ground pins on 120VAC outlets on differ-
ent sides of the room may only be connected in the basement.
This leaves the possibility that the “ground” pins may have a
significant voltage differential (especially if the two 120 VAC
outlets happen to be on different phases!)
4.1.9 PCM-DAS16x/12 and Signal Source already have Isolated
Grounds
Some signal sources will already be electrically isolated from the PCM-
DAS16x/12. The diagram below shows a typical isolated ground system.
These signal sources are often battery powered, or are fairly expensive pieces
of equipment (since isolation is not an inexpensive proposition), isolated
ground systems provide excellent performance, but require some extra effort
during connections to assure optimum performance is obtained. Please refer
to the following sections for further details.
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