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Question Can I say that an ESDS product (200 Volts ESDS) is safe from ESD if the product is immediately placed on an ESD mat after an alarm occurred from a continous wristrap monitoring device? How do I test electrostatic buildup after a continous wristrap monitoring alarm? - Anonymous, Milpitas, CA
Answer If the mat surface is still properly grounded and in the dissipative range as suggested in the ESD S4.1 and ANSI/ESD S20.20 standards then your 200 Volt ESDS device may be adequately protected after placed on the ESD mat within your ESD protective area and the rules of your ESD Control program were followed.

Was the device protected when the Monitor used went into alarm state and what occured to make it go into an alarm state? First you will need to identify why the monitor went into alarm state to isolate the problem.

Some reasons that a continuous monitor may go into an alarm state are as follows:
- the wrist strap system was compromised, i.e., the band, coil cord, banana plug integrity, skin-band contact, etc. Check the grounding path of each system separately to identify the problem area, replace if necessary
- if a mat monitoring circuit is included, the mat grounding may have been compromised, check the ground connection (wire, hardware, etc.) with an ohmeter (from the common point ground to the building ground) and the mat itself (from the mat surface to the common point ground snap). Make sure the mat is properly grounded and monitored.
- the building ground had too much electrical noise (from nearby heaters, motors, etc.) that can only be detected by our monitor system. Identify noisy devices and either isolate or use separate electrical circuits.
- there was a nearby ESD event that the monitor picked up and triggered a temporary alarm state. Check the ESD protective area for Charge Device Model (CDM) problems, i.e., very conductive surfaces (bench top trim, tools, shelving, etc.) and isolate or replace with dissipative surfaces.

Once you have identified the reason for the alarm condition to be triggered, then depending on where the product was and how it was handled during the alarm condition you may have a better handle on the devices integrity.
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