Amprobe AT-7000 - Manual (Page 15)

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IMPORTANT NOTICE, PLEASE READ BEFORE YOU START TRACING
Avoiding signal cancellation problems with a separate ground connection
The signal generated by the transmitter creates an electromagnetic field around the wire.
This field is what is detectable by the receiver. The clearer this signal, the easier it is to trace
the wire.
If transmitter is connected to two adjacent wires on the same circuit (for example, hot and
neutral wires on a Romax cable), the signal travels in one directions through the first wire and
then returns (with opposite direction) through the second one. This causes creation of two
electromagnetic fields around each wire with opposite direction. These opposing fields will
partially or completely cancel each other out, making wire tracing difficult if not impossible.
Not recommended. This
wire connection causes
signal cancellation
AT-7000-R
AT-7000-T Figure 3a
To avoid the cancellation effect, a separate ground connection method should be used.
The red test lead of the transmitter should be connected to the hot wire of the circuit
you wish to trace, and the green lead to a separate ground, such as water pipe, ground
stake, metal grounded structure of the building, or outlet ground connection of an outlet
on a different circuit. It is important to understand that an acceptable separate ground
is NOT the grounding terminal of any receptacle on the same circuit as the wire you wish
to trace. If hot wire is energized and the transmitter is properly connected to a separate
ground, the red LED on a transmitter will light up. The separate ground connection create
the maximum signal strength, because the electromagnetic field created around the hot
wire is not being cancelled by a signal on the return path flowing along an adjacent wire
(hot or neutral) in the opposite direction, but rather through the separate ground circuit.
Avoiding signal
cancellation effect
AT-7000-R
AT-7000-T
Figure 3b
To Transformer
3. main aPPLications