TECHNICAL BULLETIN TB-3049
Ground Hub Continuous Monitor
Operation, Installation and Maintenance
Made in America
more than just a few volts between ground and neutral, this
indicates either that they are not referenced to each other or
that the outlet and associated wiring should be checked for
loose connections. In this case, the Ground Hub Continuous
Monitor will sound a warning alarm and display a red FAIL
indication and should not be used for an ESD grounding
point until corrected.
Use the Ground Hub Continuous Monitor to fulfill the ANSI/
ESD S6.1 section 6.3.1 requirement. “The hot, neutral and
equipment grounding conductor shall be verified to be in the
proper wiring orientation in accordance with the National
Electric Code (ANSIINFPA-70).”
Figure 1. Desco 19219 Ground Hub Continuous Monitor
The Ground Hub Continuous Monitor is available in the
following models:
Item
19219
19224
Voltage
120VAC
220VAC
Plug
N. America
Asia / UK
Packaging
1
6
6
1
Ground Hub Monitor
10-32 x 1/4" Screws
#10 Split Washers
Certificate of Calibration
Features and Components
Neutral
Figure 2. Desco 19224 Ground Hub Continuous Monitor
Load / Hot
Ground
Ground Hub
Description
The Desco Ground Hub Continuous Monitor confirms the
integrity of the resistance path from the common ground
point to electrical ground. It is designed in accordance
with ESD TR 12-01 to “monitoring equipment ground
connections.”
When the Ground Hub Continuous Monitor is plugged into
an AC outlet, the green LED illuminates when both the
outlet’s wiring is correct and the path to equipment ground
via the equipment grounding conductor is intact. The monitor
provides 12 verified ground points when in PASS condition.
The red LED illuminates when either the outlet’s wiring is
incorrect or the path to equipment ground is defective.
The outlet ground line is tested by measuring voltage
between it and the neutral line. It is normal to have a few
volts of AC induced on the neutral line. If the Ground Hub
Continuous Monitor measures only a few volts, the ground
line to neutral impedance is low and the ground line would
make a suitable ESD ground point. If the monitor measures
Outlet Status
FRONT VIEW
BACK VIEW
Figure 3. Desco 19219 Ground Hub Continuous Monitor
features and components
DESCO WEST
- 3651 Walnut Avenue, Chino, CA 91710 • (909) 627-8178 • Fax (909) 627-7449
DESCO EAST
- One Colgate Way, Canton, MA 02021-1407 • (781) 821-8370 • Fax (781) 575-0172 • Website:
Desco.com
TB-3049
Page 1 of 3
August 2014
© 2014 DESCO INDUSTRIES, INC.
Employee Owned
Earth
Load / Hot
Neutral
Outlet Status
Earthing Point
FRONT VIEW
BACK VIEW
Figure 4. Desco 19224 Ground Hub Continuous Monitor
features and components
Operation
Plug the Ground Hub Monitor into an outlet to see if the
green PASS LED illuminates. This signifies that the outlet
is correctly wired and the path to equipment ground is
intact. The screw that holds the outlet cover on may be
used to secure the Ground Hub Monitor so that it cannot
be unplugged. Use the included screws and split washers
to connect ring terminals (not included) to the Ground Hub
or the banana jacks (not included) to connect banana plugs
(see Figure 5).
(Wires not included)
Figure 6. Ground Hub Continuous Monitor in-use photo
TESTING THE GROUND HUB MONITOR
NOTE: The following procedure should only be done by
someone familiar with voltage hazards. This procedure will
work for 220VAC as long as the neutral and ground are
referenced. 220VAC produced with out of phase 110VAC-
Ground-110VAC will produce a FAIL result.
Isolate the ground plug from the Ground Hub Monitor by
inserting the monitor into a 3 to 2 plug adapter.
A. PASS OUTLET -
Connect a 5 kilohm resistor @ 5%
tolerance between the supply ground
and tester ground. The PASS LED
should remain illuminated until the
resistor is removed. This test confirms
the PASS point for the neutral-to-ground
resistance.
B. FAIL OUTLET -
Connect a 12.5 kilohm resistor @ 5%
tolerance between the supply ground
and tester ground. The FAIL LED
should remain illuminated until the
resistor is removed. This test confirms
the FAIL point for the neutral-to-ground
resistance.
Figure 5. Installing ring terminals and banana plugs to
the Ground Hub
DESCO WEST
- 3651 Walnut Avenue, Chino, CA 91710 • (909) 627-8178 • Fax (909) 627-7449
DESCO EAST
- One Colgate Way, Canton, MA 02021-1407 • (781) 821-8370 • Fax (781) 575-0172 • Website:
Desco.com
TB-3049
Page 2 of 3
© 2014 DESCO INDUSTRIES, INC.
Employee Owned
Specifications
Input Voltage:
120VAC ±15% (Item 19219)
220VAC ±15% (Item 19224)
Current Drain:
< 10mA
Equipment Ground Conductor Resistance Limits:
10 kilohms (nominal) (19219 only)
Dimensions:
2.0" x 3.0" x 1.3" (5.1cm x 7.6cm x 3.2cm) (Item 19219)
2.0" x 3.0" x 2.0" (5.1cm x 7.6cm x 5.1cm) (Item 19224)
Operating Temperature:
0° - 40°C
Limited Warranty
Desco expressly warrants that for a period of one (1) year from the date
of purchase Desco Continuous Monitors will be free of defects in material
(parts) and workmanship (labor). Within the warranty period, a credit
for purchase of replacement Desco Continuous Monitors, or, at Desco’s
option, the Continuous Monitor will be repaired or replaced free of charge.
If product credit is issued, the amount will be calculated by multiplying
the unused portion of the expected one year life times the original unit
purchase price. Call Customer Service at 909-627-8178 (Chino, CA) or
781-821-8370 (Canton, MA) for Return Material Authorization (RMA)
and proper shipping instructions and address. Include a copy of your
original packing slip, invoice, or other proof of date of purchase. Any unit
under warranty should be shipped prepaid to the Desco factory. Warranty
replacements will take approximately two weeks.
If your unit is out of warranty, Desco will quote repair charges necessary
to bring your unit up to factory standards. Call Customer Service at 909-
627-8178 (Chino, CA) or 781-821-8370 (Canton, MA) for a Return Material
Authorization (RMA) and proper shipping instructions and address.
Warranty Exclusions
THE FOREGOING EXPRESS WARRANTY IS MADE IN LIEU OF
ALL OTHER PRODUCT WARRANTIES, EXPRESSED AND IMPLIED,
INCLUDING MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE WHICH ARE SPECIFICALLY DISCLAIMED. The express
warranty will not apply to defects or damage due to accidents, neglect,
misuse, alterations, operator error, or failure to properly maintain, clean or
repair products.
Limit of Liability
In no event will Desco or any seller be responsible or liable for any
injury, loss or damage, direct or consequent, arising out of the use of or
the inability to use the product. Before using, users shall determine the
suitability of the product for their intended use, and users assume all risk
and liability whatsoever in connection therewith.
DESCO WEST
- 3651 Walnut Avenue, Chino, CA 91710 • (909) 627-8178 • Fax (909) 627-7449
DESCO EAST
- One Colgate Way, Canton, MA 02021-1407 • (781) 821-8370 • Fax (781) 575-0172 • Website:
Desco.com
TB-3049
Page 3 of 3
© 2014 DESCO INDUSTRIES, INC.
Employee Owned
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