Conductive Floor Test

DOE-HDBK-1092-98

5.1.4.5 CONDUCTIVE FLOOR TEST

Before use, tests shall be conducted on all conductive floors; subsequent tests shall be made at least

semiannually. Test results shall be permanently recorded and a copy filed in a central location.

Instruments used in testing shall be used only when the room is free from exposed explosives and

mixtures of flammable gases.

Maximum floor resistance shall be measured with a suitably calibrated insulation resistance tester

that operates on a normal open-circuit output voltage of 500 V dc and a short-circuit current of 2.5

mA with an effective internal resistance of approximately 200,000 ohms. Minimum floor resistance

shall also be measured with a suitably calibrated ohmmeter.

Each electrode shall weigh 2.3 kg and shall have a dry, flat, circular contact area 6-1/2 cm in diameter,

which shall comprise a surface of aluminum or tinfoil 1.3 to 2.5 mm thick, backed by a layer of rubber

0.6 to 0.65 cm thick, and measuring between 40 and 60 durometer hardness as determined with a

Shore Type A durometer (ASTM D-2240-68).

The floor shall be clean and dry. Only electrode jelly shall be used to establish a good contact.

(Brushless shaving soap and saline solution shall not be used.)

The resistance of the floor shall be more than 5,000 ohms in areas with 110-V service, 10,000 ohms

in areas with 220-V service, and less than 1,000,000 ohms in all areas, as measured between a

permanent ground connection and an electrode placed at any point on the floor and also as measured

between two electrodes placed 3 ft apart at any points on the floor. Measurements shall be made at

five or more locations in each room. If the resistance changes appreciably during a measurement, the

value observed after the voltage has been applied for about 5 sec shall be considered the measured

value. (See Figure 5-1.)

5.1.4.6 HUMIDIFICATION

Humidification to prevent accumulations and subsequent discharges of static electricity is usually

effective if the relative humidity is above 60%. However, certain materials such as metallic powders

and some pyrotechnic mixtures cannot be exposed to air with 60% relative humidity because of the

possibility of their spontaneous ignition. Where this technique is used to prevent accumulations of

static electricity, a daily check of the humidity levels will be performed before work starts.

5.1.4.7 GROUND-FAULT CIRCUIT INTERRUPTER

Ground-fault circuit interrupter (GFCI) protection shall be provided in static-grounded areas where

personnel are using hand-held, portable, ac-powered electrical equipment operating at 120 V.

5.1.5 ELECTRICAL EQUIPMENT AND WIRING

Electrical equipment and wiring in locations containing explosives shall comply with relevant

provisions of the NEC and DOE regulations, plus the requirements in this section.

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