NECESSITY IS THE MOTHER OF EXTECH’S
NEWEST CONTINUITY TESTER
Before recently, the problems presented by continuity testers available on the
market were, to say the least, shocking.
It’s not that there weren’t a number of devices available, but they all had serious
shortcomings. While some were intrinsic to each device, there was one issue that united
them all: ringing out a line (as continuity testing was referred to earlier in its infancy) was
extremely exasperating to do on your own. With all of the testers, the electrician was
ultimately required to place a continuity device on the end of a wire pair, locate what was
thought to be the other end and connect the wires together. They then had to go back to
the initial spot to see if the light was on and return to the other end to take the wires apart.
If the electrician was working on his or her own, the walking in circles got to be pretty
tedious.
For the electrician performing a large volume of work on older homes, rather than
new construction, there would likely be a greater need to figure out wiring patterns.
Residents would see wires sticking out of their walls and think, “Is this a speaker wire, or
telephone wire, or what? And where does it go?”
Each type of continuity testing device had its own unique problems as well.
Multimeters, which had long been used for continuity testing, were big and bulky;
consequently, they didn’t easily lend themselves to being hung from a wire; they needed
to be propped up, an often clumsy operation, not to mention the time spent finding
something to do the propping. Another concern with multimeters was their long leads –
usually around 36 inches in length – which would result in a tangled mess. And the
meter’s point probe had to either be held on the wire or taped, another inconvenience.
Flashlight-type continuity testers presented similar issues: long leads that got
tangled with themselves or other tools in the toolbox, as well as being too heavy to hang
from a wire by their three-foot clip leads (especially with the weight of two “D” batteries
inside). What’s more, because flashlights are round they tend to roll and fall when
propped up on a ladder. This would cause either breakage of the flashlight bulb or a dent
in a customer’s hardwood floor. And although an electrician might sometimes be able to
position the flashlight in order to see it from the room that was being tested, the bulb’s
invariably weak illumination still necessitated a trip back to the room in which the
flashlight was positioned, to be completely sure that the light was on.
There were also inexpensive, pen-shaped continuity testers, with a single wire
coming out and powered by two penlight batteries. Though they did have some utility as
mini-pocket flashlights, they featured just one lead; the user had to touch the other wire to
the metal flashlight casing, meaning it had to be taped to it or held on the wire by hand, a
not-so-minor annoyance.
We’ve all heard the expression, “Necessity is the mother of invention.” Clearly,
the necessity for a better continuity tester in the marketplace would eventually lead to its
invention. And it did, thanks to a partnership between a retired electrician named Joe
Blanchard and Extech Instruments, a major supplier of test and measurement equipment
for the industrial marketplace. Blanchard had the seed of an idea that might form the
foundation of a far more effective solution.
The idea started as a somewhat rudimentary device. It actually began as a small
enclosure containing a 9-volt battery. The relatively high-voltage battery would not only
generate a brighter light, it would also allow the current to overcome any resistances, the
slightest of which can affect continuity measurement. The 9-volt battery would also
make the device lighter, which would allow it to support its own weight while clipped to
even the thinnest wires.
The improvements did not stop there - not by a long shot. It was decided to pulse
the circuit, so that the light would blink on and off. Not only was the pulsing circuit
conservative on current, it made the light far easier to see from a distance. The existing
bulb was switched out for a red, super bright LED, enhancing the light’s visibility even
further under virtually all ambient conditions.
Next, the leads were shortened to eight inches, which helped remediate the
tangling problem. The reasoning was sound: When electricians are measuring continuity,
the need to stretch the leads longer than a foot is virtually non-existent.
The addition of the remote probe was perhaps the single most significant
enhancement. Despite the previous fine-tuning, there would still be times when the
electrician would be required to walk back and forth between rooms while testing wires.
The remote probe alleviated the situation; this two-part system was unambiguous and
would provide proof positive when the tester found the proper tail end of the wires being
tested.
Lastly, a loud beeper was added that would pulse in sync with the tester’s light.
Because it could be heard from two to three rooms away, it greatly augmented the oneman operation.
All in all, four versions of the new tester were produced, including the use of a
low-power integrated circuit in the third version, and reducing the total number of
components in the fourth and final version. Not completely satisfied with the tester’s
performance, however, Extech engineers and technicians then tweaked the device along
with its final “look.”
“What had started as a homegrown solution to a nagging problem had become a
market reality,” said Blanchard.
This revolutionary gadget, which features the unique capability for single-person
operation of wire and cable continuity checking and identification, is now the CT20
Continuity Tester Pro. The CT20, which became available for retail distribution in
October 2006, is a boon to any electrician whose current continuity testing device is
causing them fits. This affordable test product, most importantly, eliminates the need for
a person to be at both ends of the wires during a continuity test. It is a perfect tool not
just for electricians, but for cable TV and audio systems installers, alarm technicians,
HVAC installers, auto repair technicians, handymen and do-it-yourself homeowners.
The CT20 is a two-part system consisting of the master Continuity
Tester/Transmitter and a unique two lead, bi-color (red/green) LED Remote Probe. The
master Continuity Tester/Transmitter is used for local continuity testing and remote
location wiring identification. Using the Remote Probe allows for single-person remote
continuity testing when identifying cables, verifying individual wire polarity labeling and
also labeling long-distance wire/cable runs where the other end of the wires are in a
different, i.e. “remote,” area.
The Remote Probe’s bright, pulsating LED is visible even in bright daylight areas.
The LED flashes green when wiring is properly identified with respect to the polarity of
the transmitter unit’s color-coded test leads (Polarity Differentiation). The probe LED
then flashes red when its leads are attached to the tested wires in reverse order. The
master Continuity Tester/Transmitter features a bright flashing LED and a loud pulsating
beeper which can be heard over high background noise. This combination of the two
parts allows a single user to identify up to three grouped wires or cables at a time for
correct labeling, with only one trip to the other end of the wire or cable location.
Lightweight and pocket-sized, both parts of the Continuity Tester Pro feature alligator
clips to enable them to hang from the wires/cables under test.
Blanchard is satisfied with the final product as well: “It’s hard to believe that a
device that was born from frustration has now evolved into a potentially new market.”
As ‘testing tools for the lone worker’ become more prevalent in today’s highpriced economy. Extech has earned a worldwide reputation for innovation and continues
to develop unique products that continue to make the lives of so many workers that much
easier.
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