There are a few types of wrist strap available in the market place.
As wrist straps are the focal element in an ESD Control, therefore it is important to buy a correct wrist strap before use.

When we think about a wrist strap, we always think of a wrist strap band and its cord.
The band can either be made of fabric, which is elastic and adjustable or made of metal.
You can get a wrist strap grounding cord of different length, e.g. 4ft or 6ft.

A wrist strap is used to drain any static charges, which are built up within a person’s body. The wrist strap won’t work alone. It always teams up with a wrist strap outlet or wrist strap monitor to function completely.

The wrist strap grounding cord may contain a single conductor or dual conductors.
There is a restriction when a user teams it up with a wrist strap monitor.

A resistance wrist strap monitor only works well with a dual conductor wrist strap.
Here is an example on how the dual conductor wrist strap works on a 3M725 monitor: 3M725 wrist strap monitor performs a resistance measurement by applying an electrical current of less than 1 microAmp. The path for the current is through one conductor of the wrist strap grounding cord that contains a current-limiting resistor, through one side of the wrist band, through the skin of the wearer under the band, through the second side of the wrist band, through the second conductor of the wrist strap grounding cord that contains a current-limiting resistor and finally back to the monitor.

The benefit of using a wrist strap monitor is that it tells the user through an audible alarm and a visual red light indicator when a user is not properly grounded.

Lately a wireless wrist strap appears in the market. This wireless wrist strap does not utilize a grounding cord. It works based on corona discharge mechanism.

To know whether a wrist strap functions as designed, it is always encouraged to verify the effectiveness of the wrist strap before use.
One way is to use a Charge Plate monitor with a graphical recording device to check the body voltage of a person after he wears the wrist strap. At almost zero voltage would indicate the wrist strap functions well and a high voltage would indicate it does not function as intended.

Related posts:

1. Tips for ESD Coordinator: Buying Your ESD Wrist Strap Continuous or Constant Monitor ESD wrist straps are the first layer of ESD protection...

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This entry was posted on Monday, June 25th, 2007 at 12:46 and is filed under ESD personnel grounding. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.