Conductive Floors, Shoes, Mats, and Wristbands

DOE-HDBK-1092-98

resistance is not to exceed 10 ohms because of the lightning protection system. For existing

equipment, the rate of static electricity generation shall be considered before changes are made in

grounding systems. The resistance of conductive rubber hose shall not exceed 250,000 ohms. (See

NFPA 77 and NFPA 780 for further information.)

5.1.4.3 CONDUCTIVE FLOORS, SHOES, MATS, AND WRISTBANDS

Conductive floors and shoes should be used for grounding personnel conducting operations

involving explosives that have an electrostatic sensitivity of 0.1 joule or less. Many flammable

liquids and air mixtures can be ignited by static discharge from a person. In areas where personnel

come close enough to have possible contact with static-sensitive explosives or vapors, conductive

floors shall be installed except where the hazards of dust-air or flammable vapor-air mixtures are

eliminated by adequate housekeeping, dust collection, ventilation, or solvent-recovery methods.

Conductive floors may also be required where operations are performed involving EEDs that contain

a static-sensitive explosive.

Conductive floors are not required throughout a building or room if the hazard remains localized. In

such cases, conductive mats or runners may suffice. These mats or runners shall be subject to all the

specifications and test requirements that apply to conductive floors. Conductive wristbands may be

substituted for conductive mats and footwear at fixed, grounded workstations or outdoor location.

5.1.4.4 SPECIFICATIONS FOR CONDUCTIVE FLOORS AND WRISTBANDS

Conductive floors shall be made of nonsparking materials such as conductive rubber or conductive

flooring material and shall meet the following requirements:

1. The flooring and its grounding system shall provide for electrical resistance not to exceed

l,000,000 ohms (measured as specified in Section 5.1.4.5).

2. The surface of the installed floor shall be reasonably smooth and free from cracks. The

material shall not slough off, wrinkle, or buckle under operating conditions. Conductive tiles

are not recommended for use in areas where contamination can be caused by explosive dust.

The large number of joints and the tendency of tiles to loosen provide areas where explosive

dust can become lodged and that are not easy to clean with normal cleaning procedures.

3. Where conductive floors and shoes are required, resistance between the ground and the wearer

shall not exceed 1,000,000 ohms, which is the total resistance of conductive shoes on a person

plus the resistance of floor to ground. Where conductive floors and shoes are required,

tabletops on which exposed explosives or dust are encountered shall be covered with a

properly grounded conductive material meeting the same requirements as those for flooring.

4. Conductive floors shall be compatible with the explosive materials to be processed.

5. Conductive wristbands shall not exceed a resistance of 1,000,000 ohms between the wearer

and ground. This resistance shall be measured with a suitably calibrated ohmmeter. Wristbands

shall be of a design that maintains electrical contact with the wearer when tension is applied

to the ground lead wire or the wristband is placed under strain.

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