Personnel Grounding
The Most Uncontrollable…
Component within an EPA is its personnel. Static charges are generated by movement and careful consideration must be given to the most appropriate form of grounding if these hazards are to be controlled. Dependant upon the structure of the EPA, the components used in personnel grounding will vary but will usually include wrist and foot straps and workwear.
The BS EN 61340-5-1:2007 Standard stipulates that wrist straps should combine a band that fits snugly around the wrist and a cord to connect the band to an earth bonding point (EBP). The wrist strap should also incorporate a quick release connection and the cord should be connected electrically to the inner surface of the band.
The conducting parts of the connecting system should be shrouded in insulating or dissipative materials when the band and cord are connected together.
In the case of footwear, the Standard states that footwear should meet the required resistance to EPA ground, as shown below.
Garments should completely cover all clothing on the arms and torso and there should be electrical continuity between all parts of the garment. Garments should have characteristics, on the outward facing surface, in accordance with the table below. Finally, garments complying with ESD requirements should also be clearly marked with the ESD warning symbol.
ESD Protective Item Requirements
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Item Requirements
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Surface Resistance (Rs) OR
Point-to-point Resistance (Rp)
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Resistance to EPA Ground OR
Groundable Point (Rg)
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Charge Decay OR End-to-end Resistance (Re) |
| Gaments |
Rp Ω 1 x 10^12
For minimum value see note 1 |
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To 10% of initial value (maximum 1000V) in less than 2s |
| Wrist strap as worn |
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7.5 x 10^5 Ω Rg Ω 3.5 x 10^7 |
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| Footwear as warn on metal plate |
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5 x 10^4 (1 x 10^5/shoe)
Rg Ω 1 x 10^8 See note 2 |
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Note 1: There is no minimum value of resistance for the protection of ESDS. However, a minimum resistance value may be required for protection or safety. See relevant national requirements and/or IEC 61010-1, IEC 60479, IEC 60536 and IEC 60364.
Note 2: When the footwear/floor systems are used as the primary means of grounding personnel, the resistance of the combination shall be determined by the ESD co-ordinator and is recommended to be between 7.5 x 10^5 Ω and 3.5 x 10^7 Ω.
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