Safety Practices - hdbk109220040172

DOE-HDBK-1092-2004

10.8.3.3 SAFETY PRACTICES

An analysis of high-voltage circuits should be performed by a qualified person before work

begins unless all exposed energized parts are guarded as required for high-voltage work. The

analysis must include fault conditions where circuit current could rise above the nominal rated

value as explained here and shown graphically in Figure 10-1. Depending on the results of the

analysis, any of the following may apply:

1. If the analysis concludes that the current is above 5 mA or energy is above 10 joules,

then the work is considered to be energized work and should be performed in

accordance with Section 2, "General Requirements" and/or Section 7, "Work In Excess

of 600 Volts."

2. If the analysis concludes that the current is between 0.5 mA and 5 mA and between 0.25

and 10 joules, then the worker may be exposed to a secondary hazard (e.g., startle

reaction) that must be mitigated.

3. If the analysis concludes that the current is below 0.5 mA and below 0.25 joules, then

the worker exposure is minimal and no special precautions are required.

High-voltage supplies that use rated connectors and cables where there are no exposed

energized parts are not considered hazards. Connections shall not be made or broken with the

power supply energized unless they are designed and rated for this type of duty (e.g., load-

break elbows). Inspect cables and connectors for damage and do not use if they are damaged.

Exposed high-voltage parts must be guarded to avoid accidental contact.

10.8.4 RADIO-FREQUENCY/ MICROWAVE RADIATION AND FIELDS

The DOE complex conducts R&D programs that involve sources of radio-frequency/microwave

(RFMW) nonionizing electromagnetic radiation. Devices that may produce RFMW radiation

include telecommunications and radar equipment, industrial equipment such as radio-frequency

heaters, and scientific and medical equipment such as magnetic resonance imagers and

klystron tubes. The nationally recognized consensus standard for personnel exposure to radio-

frequency radiation is ANSI/IEEE C95.1(1999), Electromagnetic Fields, Safety Levels with

Respect to Human Exposure to Radio Frequency.

10.8.4.1 HAZARDS

1. RF amplifiers frequently use dc high-voltage power sources.

2. There may be x-ray hazards (when supply voltage exceeds 10 kV and there are

evacuated components).

3. Currents maybe induced in conductive objects or metal structures that are not part of the

RF structure.

4. RF currents can cause severe burns.

5. Falls from towers may result from RF burns from antennas.

6. Electromagnetic interference may cause equipment to malfunction.

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