9821 Desco, 9821 Datasheet - Page 3

• Manufacturer Part Number: 9821
• Description: CORD CMMN GRND 10MM W/RES 10'
• Manufacturer: Desco

Specifications of 9821

• Accessory Type: Ground, Common Point - for Bench Mat with Resistor
• For Use With/related Products: 2 Banana Plug Wrist Straps
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• Other names: 9820R

TB-2007 Page 3 of 4
Figure 5. Grounding strategy for workstations without AC power.
Figure 6. Block diagram of a ground-integrity monitor.
Testing Is a Must
always be tested before depending
on a grounding system. Accurate,
reasonably priced and easily
operated systems analyzers are
available. The analyzer used
should both detect flaws in the
system and also verify the wiring
configuration per the National
Electrical Code. Electricians aren’t
needed for these tests unless
discrepancies are noted.
analyzer should be able to detect
flaws such as an equipment
ground shorted to neutral in the AC
outlet box. It should also be
capable of testing equipment-
ground impedance by injecting AC
current into the equipment-ground
conductor and measuring between
it and the neutral conductor. ECOS
Corp. (Oak Park, IL, Phone 708-
383-2525, Fax [phone]), a
consultant on AC distribution and
grounding, recommends 1 S
between ground and neutral.
Electrical systems should
To maximize safety, the
DESCO EAST - One Colgate Way, Canton, MA 02021-1407 • [phone] • Fax [phone] • Web Site: http://www.desco.com
DESCO WEST - 3651 Walnut Avenue, Chino, CA 91710 • [phone] • Fax [phone]
Doing It Yourself
necessary, there are adequate
means of measuring earth-ground
resistance in AC systems. Install a
5/8-in. by 6-ft. copper rod in the
earth near an electrical circuit. Using
a specialized ground-resistance
tester, measure the earth’s
resistance between your auxiliary
earth ground and the AC system’s
ground conductor. Ordinary meters
are not recommended for this
measurement due to the possibility
of invalid measurements; ground-
resistance testers can guard against
earth currents (and consequent
measurement inaccuracies); the
typical VOM cannot.
depending on the nature and
moisture of the soil and the physical
implementation of the system
ground. For ESD purposes, the
maximum resistance allowable for
rapid static decay is about 1 MS
however, if the AC system ground
meets Code requirements, the
resistance should measure less
than 100 S.
Though it should rarely be
The resistance will vary
Item Nos. 09740 and 09835
provide a secure ground at
each work station, and comes
complete with grounding wire
and instructions.
Wrist Strap Ground
Grounds Mats,
Grounds Wrist
Straps, and
Tests at a Touch
Item No. 19350 is a wrist strap
tester that also grounds your
mat. Call us if you would like to
see one.
09740
09835