The Winning Combination
Achieve maximum safety by putting together leather protectors, rubber gloves, liners, and regular inspections.
- By Jeff Morris, Vladimir Ostrovsky
- Sep 01, 2004
YOUR hands are essentially the most important tools you have on the job. Without them, all other equipment is useless. After all, the best tools on the market still need a skilled person behind them to make them function. So it follows that protecting your hands is among the highest-priority safety steps you can take. By following guidelines and using the proper protective equipment, you can protect yourself when you make accidental or intentional contact with the electrical hazards.
There are three main layers to hand protection, and each must accomplish its set task for a complete solution to safely working with electrical lines. Those three layers are liners, rubber insulating gloves, and leather protectors.
The second layer--the rubber insulating gloves--is where most of the protection from electrical current is found. These are among the most important articles of personal protection for electrical workers. They have to incorporate the necessary high dielectric and physical strength, as well as the comfort and flexibility to make them wearable. Proper fit is the first step to flexibility and comfort during wear. Measure around the palm of your hand and allow a little extra room for liner gloves.
The circumference of your hand in inches provides you with the size of the glove. Most gloves come in full and half sizes from 8 to 12. Getting the proper fit helps minimize chafing and fatigue and will extend the life of the glove itself.
Rubber insulating gloves are of made in a variety of classes that correspond to the thickness of the gloves and the level of protection they offer. Aside from using the right class of gloves for the work you are doing, there are numerous glove styles each electrical worker can choose from.
Rubber mittens offer the same protection as the five-finger gloves but keep the wearer warmer during the harsh, cold months. The thumb and index fingers have their own compartments, but the middle, ring, and pinky fingers share one. This allows for full functionality and dexterity while keeping most of the hand warmer.
Also available are different styles of cuff. The regular cuff is the default if no other style is specified when ordering. The regular cuff shape is in a straight angle out from the wrist, and the cuff is cut parallel to the wrist line. The bell and flare cuffs have more room immediately after the wrist to allow for heavier clothing and more layers in winter and more airflow to the hands in summer. The bell widens just after the wrist and continues to the cuff in a relatively straight line. The flare widens and continues to widen gradually to the cuff. All 18-inch long gloves are available with straight and contour cut at the end. The contour cuff is cut at an angle to allow for more comfortable bending at the elbow. The front of the arm is covered for 18 inches, but the back won't bunch or bend when the elbow is bent. Many electrical workers may find it beneficial to have two types of glove to assure maximum comfort during different times of the year.
Class 00 gloves are available in red and blue. Class 0 gloves are available in red, yellow black, and blue. Classes 1 through 4 are available in red, yellow, and black. Classes 1 through 4 also are available in combination of colors for ease of visual inspection.
The final layer is the leather protector glove. These should always be worn over rubber insulating gloves to provide the needed mechanical protection against cuts, scrapes, and punctures. Made from top-grade leather, these gloves fit over top of the rubber insulating gloves and take the brunt of the physical contact with equipment and tools. Leather can take more of the snags, splinters, pinches, and general wear than the rubber gloves can endure safely. The non-metallic buckle and various lengths of cuffs (see the table for proper protector length) also add to the protection offered by leather protectors. These gloves should be inspected before every use. Replace leather protectors with the first signs of cuts, cracks, or thin spots.
Storage and Inspection of Rubber Insulating Gloves
Natural and synthetic rubber both provide electrical workers with the highest levels of electrical insulating protection. However, to maintain this level of protection and ensure a long life, it is essential to care for and store gloves and sleeves correctly.
Storage should be in a bag or roll-up corresponding to the length of rubber gloves. Using a bag that is too large will allow for sagging and may lead to additional stresses on certain parts of the gloves. A bag that is too small may crease the gloves, leading to cracking and cutting. Store only one pair of gloves in the bag fit for that pair. Forcing more than one pair into a single bag could damage each pair. Bags are made from heavy-duty canvas duck or reinforced vinyl, ensuring that the equipment lies flat and lasts longer. You should use care when you remove gear from or return it to the storage bags.
Before each use, inspect gloves carefully. It is important to refer to ASTM F1236 for the complete procedures for inspection. This guide is not meant to replace the full inspection described in that specification. Each inspection should include inflation and a visual inspection of the entire surface area.
These are things you should look for during the inspection:
* cracking and cutting
* chemical contamination
* UV checking
* ozone cutting, and
* rips, tears, or holes.
The problems can arise from any number of causes. Prolonged folding or compression is one of the main culprits behind cracking. The rubber at the location of the fold is strained as much as if the glove were stretched to twice its length. Storing gloves inside out promotes ozone cutting and also puts strains on the rubber. Exposure to petroleum byproducts, as well as other chemicals, may result in swelling and blistering of the rubber. Prolonged sunlight exposure can lead to UV cracking, while metal splinters and sharp objects can lead to snags and holes.
Taking care in how you use your gloves, as well as how you store and handle them, will assure a longer life of the gloves and better protection for you. It really comes down to allowing the gloves to remain in their natural shape away from sunlight, chemicals, and sharp objects.
To test your gloves in the field, inflate them to one and a half times their normal size for Type I gloves and one and a quarter times for Type II SALCOR. Inflating will help make cracks, holes, and other problems more apparent. Listen closely, as well, for sounds of escaping air as a sign of holes and cracks. If a field inflator isn't available, roll the gloves tightly with the cuff together to trap air inside. Then press firmly and listen for escaping air. Inflating should be done both right side out and inside out.
Take your time to look carefully at the entire surface of the gloves and. Check carefully in between the fingers and along natural folds. If you find any problem or signs of physical damage, turn in the gloves for a thorough inspection, cleaning, and testing.
Manufacture, Testing, and Care
Rubber insulating gloves are manufactured by dipping porcelain forms into a tank of liquefied rubber. The thin layer of rubber is allowed to dry and the process is repeated until the desired thickness is reached. Depending on the voltage class of the glove, the dipping/drying process may be repeated more than 30 times. Once the gloves have had their final dipping and have dried completely, they are cut to length, the reinforcing bead is rolled, and the ASTM label and manufacturing information is applied along with any additional marking.
The gloves are cured in an autoclave under steam pressure and heat. After curing, the gloves are visually inspected; gloves with imperfections are rejected. The gloves are then given a halogenation treatment, also known as chlorination, to increase comfort and wearability. The gloves are electronically tested according to ASTM D120/IEC 903 specifications. Following the electrical test, the passing gloves are given another visual inspection before they are boxed and shipped.
It is then up to each electrical worker to make sure his gloves are properly cared for. This starts with proper storage, as described above. It is very important to take proper steps in protecting your hands--and that starts with fitting the proper gloves for the job, to washing up with the right cleansers when the work is complete.
It is very important to provide excellent care for the rubber gloves. These gloves may be the only barrier between the deadly effects of the electricity and the person wearing these gloves. Let?s look at the recommended procedures and practice for storage inspection and care of insulating rubber gloves and leather protectors.
Storeroom and toolroom storage
Rubber gloves should be stored in a cool, dark area in pairs and in boxes the manufacturer provides. Avoid storage in direct sunlight. Do not store gloves in the direct pass of hot air or next to steam pipes. Gloves should not be stored in the room where electrical testing is done. Ozone generated during the electrical test can damage gloves. Do not store gloves inside out. Storing inside out will create a mechanical stress. Mechanical stress is one component (ozone is the other) that will create ozone damage of rubber insulating gloves.
Gloves should be stored in glove bags. Nothing should be piled on top of them to create a mechanical stress. It is recommended to store gloves gantlet first in the bag. This will prevent foreign materials from falling into the gloves and damaging them.
If gloves get contaminated with petroleum-based products, clean them before placing them in the glove bag (if gloves are not cleaned from petroleum-based products, they will cause rubber to swell). This may not affect the dielectric properties of the gloves but can reduce the mechanical resistance to puncture, snag, or tear. Do not roll, fold, tape, or tie gloves.
Field inspection of rubber gloves
Make a rule of inspecting gloves every time prior to putting them on. It takes only a few minutes but may save your life. Gloves may be inspected by one of two ways:
* Hold the glove downward and grasp the cuff.
* Twirl the glove upward toward your body to trap the air inside the glove.
* Squeeze the rolled cuff into a U shape with the right hand to keep trapped air inside. Squeeze with the other hand and look for damage exposed by inflation.
* Hold the inflated glove close to your face and ear, squeezing the glove, to feel and listen for air escaping from holes.
* Hold the glove firmly closed with one hand.
* Squeeze different parts of the glove with the other hand to make certain no air leaks out.
* Turn the glove inside out and repeat the procedure.
The second procedure involves using a portable glove inflator, which allows the user to inspect a greater area of the glove, use both hands to assist inspection, and perform a better inspection. While the glove is inflated, make a thorough examination for cuts, punctures, scratches, ozone checking, corona cutting, embedded foreign materials, oil markings, or other defects that may impair its safety.
The only function that leather protectors have is to provide mechanical protection to the rubber gloves. In order to do that, protectors must be in good condition. Make sure that leather protectors are not saturated with petroleum-based products and do not have cuts or foreign material that may damage rubber gloves. Replace leather protectors when they no longer provide protection.
Rubber insulating gloves are where most of the protection from electrical shock is found. Rubber does not have very high puncture resistance against the sharp objects that are found in abundance at a work site. Leather protectors are a mechanical barrier that not only provide puncture protection, but also minimize normal wear, tear, and abrasion to help maximize the life of the gloves.
Look for leather protectors manufactured in accordance with the latest revision of the ASTM standard F696, Specification for Leather Protectors for Rubber Insulating Gloves and Mittens.
They can be made from cowhide or goatskin. Protectors made from goatskin provide excellent dexterity and durability. Cowhide protectors provide the same high level of protection as goatskin but will last much longer.
Protectors designed for use on Class 1 through 4 gloves have high-visibility cuffs to protect the area of the gloves above the wrist. Leather protectors for high-voltage rubber gloves Class 1 and above are supplied with pull straps using nonmetallic buckles. Low-voltage protectors for class 00 and 0 gloves are available with either the same pull strap or a sewn-in elastic wrist.
Proper fit of leather protectors is very important to keep your rubber gloves in top shape. Be aware that a manufacturer's leather protectors may be specifically designed to fit that manufacturer's rubber gloves. Improperly selected leather protectors will cause premature deterioration of rubber gloves. Protectors that are too small will create mechanical stress, and the combination of mechanical stress with ozone (found naturally in air) will cause what is referred to as "ozone cutting" and result in the early deterioration of your rubber gloves.
Besides matching the proper hand size of protector to rubber glove, you also must choose the proper length of protector, maintaining a minimum distance from the top of the protector cuff to the top of the rubber glove cuff. This is necessary to prevent a hazardous flashover that could occur between partially conductive (contaminated/wet) leather protectors and the worker's arm. ASTM has determined these minimum distances:
Minimum Distance Between Gauntlet and Cuff
Glove class, Distance (min.)
Just like insulating gloves, leather protectors must be frequently inspected. Protectors should be checked for metal particles, embedded wire, abrasive materials, or any substance that could physically damage the rubber gloves. Remove all foreign material before using the leather protector. Users should discard protectors that are saturated with oil or have holes in them.
Glove liners are used to improve comfort when wearing rubber gloves. There is a wide variety of liners to address different concerns when wearing rubber gloves. Use thin cotton liners in the summer to absorb perspiration and thick thermal cotton/wool liners in the winter for warmth. Consider ordering rubber gloves a half-size larger to leave room for liners, especially if thermal winter liners will be worn.
Remember, although rubber insulating gloves provide you with protection from the hazards of electrical shock, you must protect them from the everyday hazards of the work site. Maximum safety will be achieved when all of the components (i.e., leather protectors, rubber gloves, liners, and regular inspections) are combined.
This article originally appeared in the September 2004 issue of Occupational Health & Safety.