Safety precautions in the amateur station
RSGB Safety Recommendations for the Amateur Radio Station
- All equipment should be controlled by one master switch, the position of
which should be well known to others in the house or club.
- All equipment should be properly connected to a good and permanent earth.
(Note A).
- Wiring should be adequately insulated, especially where voltages greater
than 500V are used. Terminals should be suitably protected.
- Transformers operating at more than 100V rms should be fitted with an
earthed screen between the primary and secondary windings.
- Capacitors of more than 0.01uF capacitance operating in power packs.
modulators, etc (other than for RF bypass or coupling) should have a bleeder
resistor connected directly across their terminals. The value of the bleeder
resistor should be low enough to ensure rapid discharge. A value of 1/C
megohms (where C is in microfarads) is recommended. The use of earthed probe
leads for discharging capacitors in case the bleeder resistor is defective
is also recommended. (Note B). Low-leakage capacitors. such as paper and
oil-filled types. should ~ stored with their terminals short-circuited to
prevent static charging.
- Indicator lamps should be installed showing that the equipment is live.
These should be clearly visible at the operating and test position. Faulty
indicator lamps should be replaced immediately. Gas-filled (neon) lamps are
more reliable than filament types.
- Double-pole switches should be used for breaking mains circuits on
equipment. Fuses of correct rating should be connected to the equipment side
of each switch. (Note C). Always switch off before changing a fuse. The use
of AC/DC equipment should be avoided.
- In metal-enclosed equipment install primary circuit breakers, such as
micro-switches, which operate when the door or lid is opened. Check their
operation frequently.
- Test prods and test lamps should be of the insulated pattern.
- A rubber mat should be used when the equipment is installed on a floor
that is likely to become damp.
- Switch off before making any adjustments. If adjustments must be made
while the equipment is live, use one hand only and keep the other in your
pocket. Never attempt two-handed work without switching off first. Use
good-quality insulated tools for adjustments.
- Do not wear headphones while making internal adjustments on live
equipment.
- Ensure that the metal cases of microphones, Morse keys etc are properly
connected to the earthed chassis.
- Do not use meters with metal zero-adjusting screws in high-voltage
circuits. Beware of live shafts projecting through panels, particularly when
metal grub screws are used in control knobs.
- Antennas should not, under any circumstances, be connected through a
capacitor which may have HT on the other side; a low-resistance DC path to
earth should be provided (RF choke).
Note A Owing to the common use of plastic water main and sections of plastic
pipe in effecting repairs. it is no longer safe to assume that a mains water
pipe is effectively connected to earth. Steps must be taken, therefore, to
ensure that the earth connection is of sufficiently low resistance to provide
safety in the event of a fault. Checks should be made whenever repairs are made
to the mains water system in the building.
Note B A 'wandering earth lead' or an 'insulated earthed probe lead' is an is
an insulated lead permanently connected at one end to the chassis of the
equipment; at the other end a suitable length of bare wire is provided for touch
contacting the high-potential terminals to be discharged.
Note C Where necessary, surge-proof fuses can be used.
