The Secretary of the Navy, in establishing a Department of the Navy safety program, stressed, "Safety is an inherent responsibility of command...." He further outlined that, "Assignment of safety responsibility at all echelons of command is a basic requirement." This means responsibility right down through the lowest rated personnel in the command. Most noncombat accidents can be prevented if all personnel cooperate in eliminating unsafe conditions and acts. To this end, each individual is responsible for understanding and applying safety rules, standards, and regulations in all activities. Safety consciousness will help prevent personal injury and damage to property.

Some safety precautions applicable to this module deal with fumes from synthetic insulation, breathing asbestos fibers, and working around/with electrical and electronic circuits and portable power tools.

SYNTHETIC INSULATION

Almost without exception, the fumes from synthetic materials, such as plastics in high-temperature environments, are objectionable from the standpoint of health and safety. Fluoroplastics (FEP and polytetrafluoroethylene) resist decomposition at higher temperature better than most other plastics.

Exposure to fumes when working with fluoroplastics may cause a temporary flu-like condition similar to the metal fume fever (or "foundryman's fever"). These symptoms are commonly called polymer fume fever. They do not ordinarily occur until several hours after exposure, and pass within 36 to 48 hours, even in the absence of treatment.

One of the largest uses of fluoroplastics is as a wire and cable insulation. When insulated wiring is installed, soldering is a routine fabricating procedure, as is the use of a heated element to remove insulation. In neither of these operations do the combined effects of temperature, quantity of resin, and exposure time produce toxic conditions of significance, as long as normal ventilation is maintained.

Any special practices or precautions that may be required should follow the same common sense rules that apply to all soldering jobs. Prolonged soldering in confined spaces with restricted air circulation will require some ventilation for personal comfort. The same is true for open shop areas where a number of personnel are engaged in soldering or hot-wire stripping. Normal ventilation for personal comfort usually provides adequate safety. However, it is recommended that a small duct fan or "elephant trunk" exhaust be used at the workbench during soldering or wire stripping to carry away any toxic vapors.

ASBESTOS

Although asbestos-free products have been developed, older products containing asbestos materials still exist and continue to be used in the Navy. One such product is asbestos insulation used on wiring in high-temperature areas aboard ships and in aircraft.

Because of the serious health hazards of asbestos exposure, the government has imposed strict occupational health and environmental protection standards for the control of asbestos. These standards must be strictly enforced and followed by all Navy personnel.

Asbestos is a general term used to describe several fibrous mineral silicates. Major uses of asbestos include asbestos cement products, floor tiles, fireproofing, high-temperature insulation, asbestos cloth, friction materials (such as brake linings and clutch facings), various gasket materials, and miscellaneous other products.

Inhaling asbestos fibers can produce disabling or fatal fibrosis of the lungs. Fibrosis of the lungs (asbestos) comes from inhaling asbestos fibers. Asbestos is a factor in the development of lung cancer as well as cancer of the gastrointestinal tract. It may take 20 to 40 years between initial exposure to asbestos and the appearance of a cancerous condition. Know where asbestos is in your environment and avoid or take precautions to prevent exposure.

ELECTRICAL OR ELECTRONIC CIRCUITS AND PORTABLE POWER TOOLS

When working on electrical or electronic circuits, you must observe certain general precautions. The following is a listing of common sense safety precautions that you must observe at all times:

Remember that electrical and electronic circuits often have more than one source of power. Take time to study the schematics or wiring diagrams of the entire system to ensure that all power sources are deactivated.

Figure 3-13. - Fuse puller.

All supply switches or cutout switches from which power could possibly be fed should be secured in the OFF or OPEN (safety) position and tagged (figure 3-14). The tagging procedures must be done in accordance with the appropriate manual or instruction for your field of training.

Figure 3-14. - DANGER tag.

Keep clothing, hands, and feet dry if possible. When it is necessary to work in wet or damp locations, use a dry platform or wooden stool to sit or stand on, and place a rubber mat or other nonconductive material on top of the wood. Use insulated tools and molded insulated flashlights when you are required to work on exposed parts. In all instances, repairs on energized circuits must not be made with the primary power applied, except in an emergency, and then only after specific approval has been given by your commanding officer.

When approval has been obtained to work on equipment with the power applied, keep one hand free at all times (BEHIND YOU OR IN YOUR POCKET).

Never use your finger to test a "hot" line. Use approved voltmeters or other voltage-indicating devices.

High Voltage Precautions

In addition to observing the general precautions just discussed, you must observe the following additional precautions when working with high voltages:

• Do NOT work with high voltage by yourself; have another person (safety observer), qualified in first aid for electrical shock, present at all times.
• This individual, stationed nearby, should also know the circuits and location of the switches controlling the equipment, and should be given instructions to pull the switch immediately if anything unforeseen happens.
• Always be aware of the nearness of high-voltage lines or circuits. Use rubber gloves where applicable and stand on approved rubber matting. Not all so-called rubber mats are good insulators.
• Always discharge the high voltage from components or terminals by using a safety probe.
• Do NOT hold the test probe when circuits over 300 volts are tested.

Soldering Irons

• When using a soldering iron, always keep in mind the following precautions and procedures:
• To avoid burns, ALWAYS ASSUME that a soldering iron is hot.
• Never rest a heated iron anywhere but on a metal surface or rack provided for this purpose. Faulty action on your part could result in fire, extensive equipment damage, and serious injuries.
• Never use an excessive amount of solder, since drippings may cause serious skin or eye burns.
• Do not swing an iron to remove excess solder. Bits of hot solder that are removed in this manner can cause serious skin or eye burns. Hot solder may also ignite combustible materials in the work area.
• When cleaning an iron, use a cleaning cloth, but DO NOT hold the cleaning cloth in your hand. Always place the cloth on a suitable surface and wipe the iron across it to prevent burning your hand.
• Hold small soldering jobs with pliers or a suitable clamping device to avoid burns. Never hold the work in your hand.
• Do not use an iron that has a frayed cord or damaged plug.
• Do not solder components unless the equipment is disconnected from the power supply circuit. Serious burns or death can result from contact with a high voltage.
• After completing the task requiring the use of soldering iron, disconnect the power cord from the receptacle and, when the iron has cooled, stow it in its assigned storage area.

Portable Electric Power Tools

Navy specifications for portable electric power tools require that the electric cord of each tool have a distinctively marked ground wire in addition to the conductors for supplying power to the tool. (Double-insulated portable electric tools obtained from sources qualified under the applicable military specification are exempt from this grounding requirement.) The end of the ground wire within the tool must be connected to the metal housing of the tool. The other end must be connected to a positive ground. For this ground connection, specifically designed ground-type plugs and receptacles, which automatically make this connection when the plug is inserted into the receptacle, must be used. These grounded-type receptacles must be installed for all power outlets. When installed, they must be used with the grounded-type plugs to ground portable tools and equipment. If grounded-type receptacles have not yet been installed, they must be installed as soon as possible. Portable tools not provided with the ground-type plug, and miscellaneous portable electric equipment that does not have a cord with a ground conductor and grounded plug, must be given a three-conductor cord with a standard Navy grounded-type plug.

The ground wire must be connected to a positive ground.

Care must be exercised in connecting the plugs and cords. The grounding conductor of the cord must be connected to the ground contact of the plug at one end and to the metal equipment housing at the other end. The cord must be arranged so as not to create a tripping hazard. If the conductor connected to the metallic equipment housing is inadvertently connected to a line contact of the plug, a dangerous potential would be placed on the equipment casing.

This could result in a fatal shock to the operator. If the cord is pulled loose from the plug, only a qualified electrician is authorized to repair it.

If the grounded-type plugs and receptacles have not been installed in the spaces where a portable tool is to be used, other types of plugs and receptacles may be used only if a separate ground wire is connected between the tool housing and a positive ground. When the tool cord does not include an extra wire for grounding, an additional insulated wire should be connected between the metal housing of the tool and ground. If the tool housing has two or more conducting parts that are not electrically connected, each part must be connected to the ground wire. Connection of the ground wire to the tool housing and to the ground must be by means of screws or bolts. The use of spring clips for either end of the grounding wire is prohibited.

When the ground connection is to be made by means other than a contact in the plug and receptacle, care must be taken to secure a good contact between the ground wire and the metal by scraping away paint from the metal to ensure a clean surface. The ground connection must be made before inserting the power supply connecting plug, and the plug must be pulled out before removing the ground connection. Frequent inspections of each of the connections of a portable electric tool must be made to ensure that the supply cord and its connections within the tool are suitably insulated and that the ground connection is intact.

The safety precautions just discussed are to protect you and your shipmates. Follow safety precautions to the letter. DO NOT TAKE CHANCES. Carelessness could cost you your life.

Q.16 What safety precaution must you observe when soldering or hot-wire stripping fluoroplastic insulated wire?
Q.17 What must be used to test an activated circuit?
Q.18 How should excess solder be removed from a hot soldering iron?