General exam: electrical and rf safety
RF exposure evaluation, grounding, electrical hazards and safe station practice. 25 questions, 10 at a time, starting with ones you haven't seen.
Rules to remember6 key electrical and rf safety rulesShow the rules
- RF energy is absorbed by the body and turns into heat, so the known biological effect is tissue heating. (p. 82)
- A harness only protects you if it is rated for your weight and still within its service life, so check both before climbing. (p. 85)
- Generators produce deadly carbon monoxide, so they must run in a well-ventilated area, never indoors or in an enclosed space. (p. 85)
- Lead from solder can stay on your hands and get into food, so wash your hands carefully after handling lead-tin solder. (p. 85)
- An interlock switches off and removes dangerous voltages when the cabinet is opened, protecting anyone who reaches inside. (p. 85)
- Lightning arrestors go where the feed lines enter the building, so a surge on the line is sent to ground before it gets inside. (p. 86)
Taken from the explanations to checked practice questions; page numbers link to the official handbook.
Sample electrical and rf safety questions
1.Which of the following steps must an amateur operator take to ensure compliance with RF safety regulations?
- APerform a routine RF exposure evaluation and prevent access to any identified high exposure areas
- BPost a copy of FCC Part 97.13 in the station
- CNotify neighbors within a 100-foot radius of the antenna of the existence of the station and power levels
- DAll these choices are correct
Show the answer
✓ A. Perform a routine RF exposure evaluation and prevent access to any identified high exposure areas
Amateurs must evaluate their station's RF exposure and keep people out of any areas found to exceed the limits; posting rules or notifying neighbors is not required.
2.What type of instrument can be used to accurately measure an RF field strength?
- AA calibrated field strength meter with a calibrated antenna
- BA receiver with digital signal processing (DSP) noise reduction
- CAn oscilloscope with a high-stability crystal marker generator
- DAn SWR meter with a peak-reading function
Show the answer
✓ A. A calibrated field strength meter with a calibrated antenna
Measuring field strength accurately needs an instrument made for it: a calibrated field strength meter used with a calibrated antenna.
3.Where should the station's lightning protection ground system be located?
- AAs close to the station equipment as possible
- BNext to the closest power pole
- CParallel to the water supply line
- DOutside the building
Show the answer
✓ D. Outside the building
The lightning ground should be outside the building so that a strike's current goes into the earth before it can reach the station or the people inside.
4.Which wire or wires in a four-conductor 240 VAC circuit should be attached to fuses or circuit breakers?
- AOnly the ground wire
- BAll wires
- COnly the neutral wire
- DOnly the hot wires
Show the answer
✓ D. Only the hot wires
Fuses and breakers belong only in the two hot wires; interrupting the neutral or ground could leave equipment energized while removing its safe return path.