Application Note

2 Fluke Corporation A million and one uses for voltage detectors
By David Welch
I work in an extremely corrosive
atmosphere. On this particular
day our crew was to disconnect
a 480 volt motor. No big deal: we
shut off the breaker and tested
the circuit with a standard volt
tester. It didn’t show any voltage
when the leads touched the
screws on the breaker phase to
phase and phase to ground. I
happened to have my Fluke 1AC
tester in my pocket and decided
to test the load side of the
breaker. The Fluke tester showed
voltage on C phase where the
breaker had failed to open. The
breaker failure was a result of
that phase in the motor ground-
ing. The test leads on my other
tester did not show the voltage,
due to the amount of corrosion
on the screws. The Fluke tester
with its inductive capabilities
might just have saved a life.
From this day forward I always
double check with my Fluke 1AC
tester. Safety is the number pri-
ority and we now issue ever
yone
a 1AC tester as standard issued
test equipment.
3. Capacitive voltage detectors
have certain limitations.
Cor-
rect operation depends upon
the capacitance between the
detector’s barrel and ground
(normally through your hand
and body). If this path is bro-
ken for any reason, the detec-
tor probably won’t work. For
example, if you’re standing on
a wooden ladder, the capaci-
tance between your body and
ground will be much less than
if you were standing on a con-
crete floor. To help avoid
incorrect detector readings,
find an installation g
round that
you can touch when using the
voltage detector
. Remember, in
a series c
ircuit, the smaller the
capacitance, the greater the
voltage drop: there might be
too much voltage drop from
you to the floor and too little
across the detector. The detec-
tors will also have a certain
minimum voltage to turn on. In
our wooden ladder scenario,
the detector might not turn on
despite the circuit being hot.
By similar reasoning, the
detector
cannot detect live
conductors inside a grounded
metal conduit.
For best results always hold
the detector by the body and
remember to keep your fin-
gers away from the tip of the
detector.
New and improved: The Fluke 1AC II Voltage Detector
Chuck Hansen of Professional Electric, Inc
. in Arlington, Wash tried out
the new Series II 1AC voltage detector and liked it - a lot. “Other voltage
detectors I’ve tried haven’t worked reliably. I couldn’t trust them. This
new 1A
C works every time. It’s never given me a false reading. I use it
primarily for troubleshooting and tracing old work.”
New feature
s on the Serie
s I
I 1A
C
•
Safety rated to C
A
T I
II 1000 V
•
Sensitivity as low as 20 V
(model depending)
•
Chirping noise and red light
alert when live voltage is present
•
Self test to ensure c
orrect operation
By Logan Cleek
Well my truck started acting up,
running rough etc. Not being an
auto mechanic I didn’t have any
diagnostic tools for that. So I
grabbed my Fluke 1AC pen, held
it by all four plug wires, and
found one that was flashing dif-
ferent than the rest. So, I pulled
that plug and found that it was
fouled and its plug wire was bad.
By Michael Hays
I’d been helping the plant elec-
trician do the industrial shop
lighting repairs/PM’s. Up until
recently, it was a two, sometimes
three man job—two in our Man-
lift, and a third on the ground, to
find and switch off power to the
various light banks. Since equip-
ping ourselves with Fluke volt
pens, we’ve reduced the ‘men’ to
two, and on week ends, just one,
as we now can quickly and
safely check the presence of
440 V ac on our lighting, as well
as other basic voltage checks,
throughout the plant.
Favorite applications from the field
Most technicians use their voltage detectors daily, to
verify power is off before working in an electrical area
and to quickly map circuits. However, like most such
practical tools, real-life offers many other applications
for a good voltage detector.