2. Safety Summary
2.8. Grounding the CT100B
When the CT100B is connected to the external AC adapter, the CT100B chassis, front panel USB,
screen, and controls are grounded through the grounding conductor of the power cord. To avoid
electrical shock, it is essential that the protective ground connection is present when operating the
unit under AC power. When disconnected from external power, the CT100B is floating relative to
earth ground, unless one of the USB ports is connected to a grounded device. In this case, the
ground of the USB device is common with the CT100B chassis, screen, and electronic controls.
At all times, the front panel BNC or SMA connector is floating and is isolated by at least 500 VDC
from the remainder of the CT100B. This eliminates measurement errors caused by common-mode
noise and slight ground-potential differences in the cable/device under test. However, care should
be taken with respect to electrical safety, as the front panel BNC or SMA shield is never safely
grounded unless connected to a safely grounded cable or device and can be considered a second live
conductor if connected to a cable or device carrying a non-zero electrical potential relative to earth
ground. This situation carries the risk of electric shock.
WARNING: The BNC or SMA connector shield represents a floating
ground and is never safely grounded even with the use of a properly grounded
AC adapter. Never use the CT100B to test any cable or device carrying a
non-zero electrical potential relative to earth ground, as this could render
an electric shock.
2.9. Danger Arising From Loss of Ground
When disconnected from the AC power adapter, the CT100B is no longer grounded unless
connected to a grounded USB device at the front panel host USB port. Because the test port
connector shield is floating relative to the remainder of the instrument, the test port connector may
be operating at an elevated voltage even when the AC adapter is connected. Therefore, the test
port connector should never be used to test any cable or device with an electrical potential relative
to earth.
WARNING: Upon loss of the protective ground connection, all accessible
parts, including the screen, knobs, and connectors, can render an electric
shock.
2.10. Explosive Atmospheres
Do not operate the CT100B in an explosive atmosphere unless your unit has been specifically
certified for that condition. Explosive Atmospheres: MIL-STD 810G, Method 511.5, Procedure I
(+55
◦
C, sea level to 4600 m).
6 CT100B TDR Cable Analyzers Operator’s Manual
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