May 1, 2004 12:00 PM, By Kevin McNamara, CNE
It may seem that a typical broadcast facility doesn't have all the safety concerns of a construction site or a manufacturing facility, but accidents happen. Here are a few important safety tips that bear review.
Accidental contact with electrical currents can cause injury, fire, extensive damage and even death.
Use a grounding stick The high voltage present in the cabinet of a transmitter is lethal. Even in the case of solid-state transmitters, where the dc voltages are low, you can be injured or killed if you happen to touch a live supply. The capacitors in dc power supplies can hold charges for long periods of time. Electrical codes require that fail-safe switches or interlocks are provided on all access doors and panels that would permit inadvertent contact with high voltage components. Don't rely on these switches. Be sure that all power is discharged using a grounding stick and subsequently hanging the ground stick on the appropriate point while performing any work.
Electrical equipment should be grounded Properly grounded electrical equipment can offer protection if the equipment should malfunction. If the electric tool states that it's doubly insulated on the manufacturer's tag, this means that there is insulation on the inside of the tool to protect the user from shock. This type of tool will only have a two-prong plug. If the tool does not state that it is doubly insulated, then there must be a third prong on the plug. This third prong, or ground prong, connects the tool to ground or earth so that in the event of a malfunction, the electricity will go through this ground prong to the earth and bypass the user's body. If the prong is broken off, the user has no protection and all the electricity will go through his body. A Ground Fault Circuit Interrupter should be used where there is a chance of contact with the moisture on the ground, such as working outside.
Wear protective clothing Wear rubber gloves and rubber-soled shoes or boots, especially if you are working around electricity in a damp environment. Everyone knows that water and electricity do not mix, but how often do you think about other liquids, such as grease, oil or solvents? Operating a drill with sweaty hands can also be a potential for electrical shock.
Never throw water on an electrical fire As mentioned, water and electricity do not mix. In fact, water is an excellent conductor of electricity, and if water is thrown on an electrical fire, it will only spread the fire. Instead, use a chemical fire extinguisher.
Practice good housekeeping Ensure that you can get to the main power source as quickly as possible, without climbing over obstructions in the event of an emergency. Keep the aisles and walkways clean and clear of garbage. Make sure all flammable liquid is stored away from the area where any electric tool will be operated. Many electric tools produce sparks, which could ignite the flammable liquid's fumes and cause extensive damage.
One of the realities of working around high-powered (and even most low-power) transmitters is that there is a high likelihood of some RF exposure. This is particularly true on certain rooftops, antenna farms (especially those with shorter towers) or perhaps near active AM antennas. Most of us have been through the training, performed the measurements and have documented proof of the hazardous areas in and around the station, but you should never assume a work area is safe without the proper measurement, or at the very least based on the calculations and charts provided in OET-65. Pocket monitors are currently available that will provide an aural and visual indication that high RF fields are present.
RF energy is odorless, colorless, tasteless and has similar properties to light energy. The good thing about RF energy is that, at this time, the only known health effect related to RF overexposure is heating. It does not hurt to be exposed. It is only when the exposure exceeds the federal limits that health affects can occur.
When the body or its parts are overexposed to RF energy from communications antennas, molecules within the organs and tissues start to move faster due to molecular excitation. This in turn causes heat. When the body becomes overheated, the symptoms resemble flu, or heat exhaustion. These symptoms may include a headache, nausea, vertigo, confusion, sensation of non-routine heating, a metallic or bad taste in the mouth and sandy-feeling eyes or blurred vision.
In severe overexposure scenarios, symptoms similar to heat stroke can occur. This is extremely rare and only happens when personnel are too close to high power broadcast or radar antennas.
The good thing about RF, if the overexposed person removes himself from the RF field before the body core temperature or tissue temperature reaches 106 degrees Fahrenheit, the body will cool itself through natural biological processes such as increased blood flow and have no permanent damage.
Broadcast facilities have several sources that might generate noise in excess of safe recommended levels such as transmitter sites, studio monitors, headphones and the use of certain power tools. Here are a few facts:
- Exposure to noise levels above 90dB will cause temporary or permanent hearing loss in humans.
- Depending on the exposure level, the hearing loss can occur over a short or long period.
- After exposure to high noise levels, people may experience ringing in the ears, earache or discomfort and the inability to hear or understand a normal conversation.
- Workers do not frequently understand they are permanently and irreversibly damaging their hearing. The process occurs over a long period of time and may not become apparent until later in life.
- Excessive noise can cause irritability, stress and distraction that may contribute to other accidents.
Wear ear protection whenever there is a chance that you will be subjected to noise that could exceed prescribed safe limits.
Accident prevention Consider the underlying accident causes described. Have you been guilty of any of these attitudes or behaviors?
Taking Shortcuts Every day we make decisions we hope will make the job faster and more efficient. But, do time savers ever risk your own safety or that of other crewmembers?
Being Overconfident "It will never happen to me" is an attitude that can lead to improper procedures, tools or methods in your work, leading to an injury.
Working with Incomplete Instructions Don't be shy about asking for explanations about work procedures and safety precautions. It isn't dumb to ask questions; it's dumb not to ask.
Failure to Pre-plan the Work A job hazard analysis is an effective way to work safely and effectively. Being hasty in starting a task, or not thinking through the process, can put you in harms way.
McNamara is president of Applied Wireless, Elkins Park, PA.