Why have a resistor? Resistors are included on foot grounders for the same reason as on wrist straps - safety. A resistor between you and direct ground helps protect against electrical shock.
Resistor values: Most companies use a 1 megohm resistor in foot grounders and wrist straps. To ensure safety, the net resistance to ground should be one half megohm or greater. The one megohm resistor was initially chosen to provide a cushion margin against the one half megohm threshold.
A recent development spearheaded by Hewlett Packard, has promoted the use of a two megohm resistor for foot grounders. The two megohm resistor takes into consideration that an individual with ESD control footwear will establish a parallel path to ground when standing on both feet. The net resistance of two parallel resistors of equal value is one half the resistance of one resistor. Therefore, the net resistance of two parallel one megohm resistors is one half megohm. The net resistance of two parallel two megohm resistors is one megohm.
Since the resistance to ground value is a combination of all the materials between you and ground, some companies with floors in the upper dissipative range have opted to not use resistors. Foot grounders using the various non marking dissipative cup materials typically do not need resistors, as their natural resistance puts them well above two megohms.
Most STATIC TECH foot grounders are available with either a one or a two megohm resistor. We make several models without resistors. We also make one model ( MG-7224 ) with a 240K ohm resistor for companies dealing with munitions standards.
have two types of resistors available. Both resistors provide effective
and dependable protection.
in molded plastic housing
|Sewn-in or Buried Resistor
Resistor is buried
between layers of Velcro