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Overview
RF safety signs should be used wherever there is the potential for
human exposure to exceed applicable limits. RF Safety Solutions' signs
provide guidance concerning three potential RF safety hazards and tower
registration information:
 | RF Fields (for both FCC and Canadian Regulations) |
| Contact Currents |
| RF Burns |
| Tower Registration |
The basic signs related to RF fields are based on the Maximum Permissible Exposure
(MPE) limits established by the Federal Communications Commission (FCC).
The FCC has two
tiers of MPE limits for RF field levels. The more restrictive limits are for
General Population/Uncontrolled exposure. Higher MPE limits may be used by
organizations operating under an RF safety program. These are referred to as
Occupational/Controlled exposure limits. See
FCC Regulations for details. Many of these signs are also available in
Spanish.
Four
different action words are used at the top of the sign in accordance with
industry standards. These action words, in order of risk potential, are:
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NOTICE |
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CAUTION |
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WARNING |
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DANGER |
Description
All signs are aluminum
panel with rounded corners and a mounting hole in each corner.
The signs are manufactured
with a special UV-resistant coating applied to the surface to increase their
life in outdoor environments. The basic NOTICE, CAUTION, and DANGER signs
are available in two sizes: 12” x 18”
(30.5 cm X 45.7 cm) and 8” x 12” (20.3 cm X 30.5 cm). The "Tower Caution",
the Contact Current, and the RF Burn signs are available in the 12" x 18" size.
RF Field Level Signs
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Sign |
Wording |
Applications |
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Radio frequency fields beyond this point may exceed the FCC
general public exposure limits. Obey all posted signs and site
guidelines for working in radio frequency environments. |
Use this sign to mark locations where RF field levels may exceed the
FCC MPE limits for General Population/Uncontrolled exposure but are
definitely below the FCC MPE limits for Occupational/Controlled exposure.
This sign is also available in Spanish. See
Spanish RF Safety Signs.
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Beyond this point: Radio
frequency fields at this site may exceed FCC rules for human exposure.
For your safety, obey all posted signs and site guidelines for working in
radio frequency environments. |
Use this sign to mark locations where RF field levels in some areas of
the site may exceed the
FCC MPE limits for Occupational/Controlled exposure.
This sign is also available in Spanish. See
Spanish RF Safety Signs.
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On this tower:
Radio frequency fields near some antennas may exceed FCC rules for human
exposure.Personnel climbing this tower should be trained for
working in radio frequency environments and use a personal RF monitor if
working near active antennas. |
Use this sign at the base of towers. It is ideal for applications
where the RF field levels on the ground beneath the tower are
insignificant and the risk potential is for personnel that climb the
tower. This sign is not appropriate for AM antenna towers.
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Beyond this point: Radio
frequency fields at this site exceed FCC rules for human exposure.
Failure to obey all posted signs and site guidelines for working in radio
frequency environments could result in serious injury. |
Use this sign to mark locations where RF field levels in some areas of
the site exceed the FCC MPE limits for Occupational/Controlled exposure.
The strong language used on this sign is designed to mark areas with
high RF field levels.
This sign is also available in Spanish. See
Spanish RF Safety Signs.
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Contact Currents and RF Burns
RF burns can result from excessive RF contact currents. Two signs are
designed for the most common applications.
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Contact currents, and potentially modest shocks,
can occur when a person touches a tower guy wire. Guy wires
are normally insulated from the tower close to the attachment point on the
tower. However, unless an additional insulator is used a few feet above
the ground (just out of reach of an adult), significant RF contact currents
can flow flow from the guy wire through the person making contact.
This is because the guy wire can act as a receiving antenna and pick up
substantial energy from the transmitting antennas. |
| RF burns are a very serious concern when working near an AM radio
tower. Very high RF voltages and currents are present on the tower,
at the feed wire from the tuning "hut" and inside the tuning hut near the
tuning circuits. These high levels are also present inside the phasor
cabinet. |
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Sign |
Wording |
Applications |
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Don't touch guy wires!
Excessive radio frequency contact currents possible.For your
safety, obey all posted signs and site guidelines for working in radio
frequency environments. |
Use this sign near guy wires that do not have an insulator a few few feet above
the ground at sites with high power antenna systems.
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Don't touch tower!
Serious RF burn hazard! Maintain adequate clearance.Failure to
obey all posted signs and site guidelines for working in radio frequency
environments could result in serious injury. |
Use this sign at AM tower sites. The location depends on the type of
fencing that is used. Use a sign near a feed wire if it is within
reach of a person standing on the ground.
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Tower Registration
The Federal Communications Commission has required that towers be
registered since 1996. The Commission requires that the tower
registration number be posted on each tower. The typical solution for
tower owners has involved the design and production of custom signs.
The Tower Registration Sign Kit is comprised of an 12" x 8" aluminum sign
and a set of vinyl numerals. The sign
has rounded corners and a mounting hole in each corner
and is manufactured with a special UV-resistant coating applied to the
surface to increase life in outdoor environments. The
exterior-rated numerals are self-adhesive.
Canadian RF Safety Signs
RF NOTICE, CAUTION, and DANGER signs are available for use in accordance
with Safety Code 6. See Canadian RF
Safety Signs.
Ordering Information
 
All signs are normally in stock. Prices are dependent on quantity.
Different signs can be combined for quantity discounts. Please
tell us what you need and we will provide you with a quotation.
Get a quotation.
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