Radio Frequency And Microwave Devices (30 KHz To 300 GHz)

Provisions shall be made to protect people from exposures at or above the Maximum Permissible Exposure (MPE) limits. Engineering controls shall be used in lieu of PPE or other administrative controls whenever possible. Shielding shall be designed by or be reviewed by a qualified individual experienced in radio frequency/microwave barrier design.

Engineering controls, such as shielding and interlocked doors, are preferred over impromptu measures such as stanchions and portable signs, or beacons. Because time-limit controls are framed in six-minute intervals, limiting exposure duration is impractical in most cases.

 

ANSI C95.1 6.2

 

Provisions shall be made to restrict access and to post appropriate warnings for locations where field strengths could exceed the MPE. Appropriate ANSI specification warning signs shall be provided to identify such areas. Signs should be mounted such that they are visible near the doorway and at some distance from it. Signs should not be mounted above doorways, as these can be overlooked.

 

ANSI C95.1 4.1.1, 4.1.2

 

Barriers and/or cages shall be provided to protect persons from contact with or close proximity to radio frequency electrical currents. These shall be made to prevent exposures exceeding the MPE for radio frequency electrical currents. These provisions shall be designed or reviewed by a qualified individual experienced in radio frequency/microwave design.

For radio-frequency, electric-current flow limits, the International Commission on Non-Ionizing Radiation Protection’s (ICNIRP’s) current flow MPE limit is more restrictive, and should be applied. Radio-frequency current flow can begin when two conductors are separated by about a foot because of electric-field interactions (capacitative coupling), so insulation by itself may not be sufficient. Increased separation distances may be needed in such cases.

 

ANSI C95.1 6.7