Safety Summary
WARNING: Only use the power cord supplied with the instrument, and then only
if the cord is in good condition. Refer all maintenance regarding the power
supply or power cord to qualified service personnel.
CAUTION: Use of any power source other than the supplied external power
adapter(s) could damage the instrument and may void the Warranty. Use only
MOHR-approved accessories.
WARNING: To reduce the risk of electric shock, disconnect all external cables
before connecting the 24 VDC external power supply.
Grounding the CT100
Grounding the CT100
When the CT100 is connected to the external AC adapter, the CT100 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 CT100 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 CT100 chassis, screen, and electronic controls. An
isolated ground power supply is an optional accessory available upon request.
At all times, the front panel BNC connector is floating and is isolated by at least 500 VDC from the
remainder of the CT100. This eliminates measurement errors caused by common-mode noise
and slight ground-potential differences in the the cable / device under test. However, care should
be taken with respect to electrical safety, as the front panel BNC 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 connector shield represents a floating ground and is never
safely grounded even with the use of a properly grounded AC adapter. Never
use the CT100 to test any cable or device carrying a non-zero electrical potential
relative to earth ground, as this could render an electric shock.
Danger arising from
Danger arising from
loss of ground
loss of ground
When disconnected from the AC power adapter, the CT100 is no longer grounded unless
connected to a grounded USB device. Because the BNC connector shield is floating relative to
the remainder of the instrument, the BNC connector may be operating at an elevated voltage even
when the AC adapter is connected. Therefore, the BNC connector should never be used to test
any cable or device with an electrical potential relative to earth.
Mohr CT100 / CT100HF Operator's Manual
7