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Triple Constant Monitor CM420

Triple constant monitor CM420  Constant monitor connection options
Triple Constant Monitor CM420
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Constantly Monitors Two ESD Wrist Straps and an ESD Mat

Triple constant Monitor CM420 monitors in "real time" three ESD workstation ground paths. Each of the two antistatic wrist straps and one antistatic bench mat while in use by operators. Monitoring for ESD ground failure on a constant basis is superior to periodically checking wrist straps with an ordinary wrist strap tester and the mat ground with an ohm meter. Ground failures detected by the constant monitor are identified immediately as they occur, before static can damage your product, not hours after the fact! Antistatic wrist straps can and do fail. Ground cords get stressed from prolonged use and usually fail inside the insulation.

Constant monitor advantages:  Immediate detection of ESD ground failures,   Detects intermittent faults that periodic wrist strap testers may not catch,   No need to rely on operators to periodically test their wrist straps,   Improves product quality and reliability,   Comparable cost to wrist strap testers but with the added benefit of constant ground path monitoring.   Eliminates periodic testing requirements of ESD wrist straps and mat grounds   Relieves supervisors and employees of periodic testing and keeping test log records.

How the CM420 constant monitor works: Operators plug their ESD wrist strap ground cord into the jack of the constant monitor at their workstation. The workstation bench mat (common point type) ground cord also connects to the constant monitor. The instrument grounds both wrist straps and continuously monitors the wrist strap and mat ground paths for failures, including proper wrist strap contact to the operators skin.

A proper wrist strap ground will cause the operator LED on the constant monitor to glow green. If a wrist strap is not being worn but is still plugged into the monitor, an audible alarm will sound for 7-10 seconds and the operator LED will blink red. If a wrist strap is being worn while plugged into the monitor and its resistance is higher than maximum, the operator LED will blink red and an audible alarm will sound.

Simultaneously, the status of the bench system ground (mat ground cord) is monitored. For normal operating resistance the BSG LED will glow green. If this resistance exceeds maximum, the BSG LED will blink red and an audible alarm will sound.

Also available: Constant Monitor S5181 to monitor only one wrist strap at a time.


  • no need for periodic wrist strap testing away from workstations
  • monitors 2 wrist straps from skin contact to earth ground, + 1 mat ground
  • provides instant warning of ground failures
  • catches even intermittent faults ordinary wrist strap testers can miss
  • bi-colored LED provides visible indication of ground path integrity
  • provides both audible and visible fault indication
  • works with standard ESD wrist straps
  • highly reliable, compact, easy to use
  • enables long term improvement in productivity and quality
  • designed for NO required adjustments. However, if an instrument is needed to verify calibration for your ESD quality program, the periodic verification tester CM420PV is available separately


  • power supply: 12VDC 200ma power adapter included
  • dimensions: 4" x 2.4" x 1" (10.2cm x 6.1cm x 2.54cm)
  • includes: model CM420 triple constant monitor, 2 remote banana jacks, patch cords, DC power adapter, mounting hardware, instructions
  • NOTE: to monitor the ESD mat ground, one of the monitors included patch cords must be connected to a common ground point type of mat ground cord. (the common ground point cord is not included)


Triple Constant Monitor CM420 is economically priced at:

Quantity 1 to 9 $ 105.95
Quantity 10 or more $ 99.95

Quantity Triple Constant Monitor CM420

Mail or FAX Order Triple Constant Monitor CM420

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Last modified: March 20, 2018

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