Elektriksel Güvenlik Eğitimi

Recognize the Hazard

The first step toward protecting yourself is recognizing the many hazards you face on the job. To do this, you must know which situations can place you in danger. Knowing where to look helps you to recognize hazards.
❑ Inadequate wiring is dangerous.
❑ Exposed electrical parts are dangerous.
❑ Overhead powerlines are dangerous.
❑ Wires with bad insulation can give you a shock.
❑ Electrical systems and tools that are not grounded or double-insulated are dangerous.
❑ Overloaded circuits are dangerous.
❑ Damaged power tools and equipment are electrical hazards.
❑ Using the wrong PPE is dangerous.
❑ Using the wrong tool is dangerous.
❑ Defective or improperly set up ladders and scaffolding are dangerous.
❑ Ladders that conduct electricity are dangerous.
❑ Electrical hazards can be made worse if the worker, location, or equipment is wet.

Inadequate Wiring Hazards

Inadequate wiring hazards
An electrical hazard exists when the wire is too small a gauge for the current it will carry. Normally, the circuit breaker in a circuit is matched to the wire size. However, in older wiring, branch lines to permanent ceiling light fixtures could be wired with a smaller gauge than the supply cable. When a wire is too small for the current it is supposed to carry, the wire will heat up. The heated wire could cause a fire.

When you use an extension cord, the size of the wire you are placing into the circuit may be too small for the equipment. The circuit breaker could be the right size for the circuit but not right for the smaller-gauge extension cord. A tool plugged into the extension cord may use more current than the cord can handle without tripping the circuit breaker. The wire will overheat and could cause a fire.

Exposed electrical parts hazards

Electrical hazards exist when wires or other electrical parts are exposed. Wires and parts can be exposed if a cover is removed from a wiring or breaker box. The overhead wires coming into a home may be exposed.

Approach Boundaries

The risk from exposed live parts depends on your distance from the parts. Three “boundaries” are key to protecting yourself from electric shock and one to protect you from arc flashes or blasts. These boundaries are set by the National Fire Protection Association (NFPA 70E).
The limited approach boundary is the closest an unqualified person can approach, unless a qualified person accompanies you. A qualified person is someone who has received mandated training on the hazards and on the construction and operation of equipment involved in a task.
The restricted approach boundary is the closest to exposed live parts that a qualified person can go without proper PPE (such as, flame-resistant clothing) and insulated tools. When you’re this close, if you move the wrong way, you or your tools could touch live parts. Same for the next boundary:
The prohibited approach boundary—the most serious—is the distance you must stay from exposed live parts to prevent flashover or arcing in air. Get any closer and it’s like direct contact with a live part. To protect against burns, there’s one more boundary: The flash protection boundary is where you need PPE to prevent incurable burns, if there’s an arc flash.

Overhead Powerline Hazards

Most people do not realize that overhead powerlines are usually not insulated. More than half of all electrocutions are caused by direct worker contact with energized powerlines. Powerline workers must be especially aware of the dangers of overhead lines. In the past, 80% of all lineman deaths were caused by contacting a live wire with a bare hand. Due to such incidents, all linemen now wear special rubber gloves that protect them up to 36,000 volts. Today, most electrocutions involving overhead powerlines are caused by failure to maintain proper work distances.

Shocks and electrocutions occur where physical barriers are not in place to prevent contact with the wires. When dump trucks, cranes, work platforms, or other conductive materials (such as pipes and ladders) contact overhead wires, the equipment operator or other workers can be killed. If you do not maintain required clearance distances from powerlines, you can be shocked and killed. (The minimum distance for voltages up to 50kV is 10 feet. For voltages over 50kV, the minimum distance is 10 feet plus 4 inches for every 10 kV over 50kV.) Never store materials and equipment under or near overhead powerlines.

Overload hazards

Overloads in an electrical system are hazardous because they can produce heat or arcing. Wires and other components in an electrical system or circuit have a maximum amount of current they can carry safely. If too many devices are plugged into a circuit, the electrical current will heat the wires to a very high temperature. If any one tool uses too much current, the wires will heat up.

The temperature of the wires can be high enough to cause a fire. If their insulation melts, arcing may occur. Arcing can cause a fire in the area where the overload exists, even inside a wall.
In order to prevent too much current in a circuit, a circuit breaker or fuse is placed in the circuit. If there is too much current in the circuit, the breaker “trips” and opens like a switch. If an overloaded circuit is equipped with a fuse, an internal part of the fuse melts, opening the circuit. Both breakers and fuses do the same thing: open the circuit to shut off the electrical current.
If the breakers or fuses are too big for the wires

In order to prevent too much current in a circuit, a circuit breaker or fuse is placed in the circuit. If there is too much current in the circuit, the breaker “trips” and opens like a switch. If an overloaded circuit is equipped with a fuse, an internal part of the fuse melts, opening the circuit. Both breakers and fuses do the same thing: open the circuit to shut off the electrical current.
If the breakers or fuses are too big for the wires they are supposed to protect, an overload in the circuit will not be detected and the current will not be shut off. Overloading leads to overheating of circuit components (including wires) and may cause a fire.

Wet conditions hazards

Working in wet conditions is hazardous because you may become an easy path for electrical current. If you touch a live wire or other electrical component—and you are standing in even a small puddle of water—you will receive a shock. Damaged insulation, equipment, or tools can expose you to live electrical parts. A damaged tool may not be grounded properly, so the housing of the tool may be energized, causing you to receive a shock. Improperly grounded metal switch plates and ceiling lights are especially hazardous in wet conditions. If you touch a live electrical component with an uninsulated hand tool, you are more likely to receive a shock when standing in water.
But remember: you don’t have to be standing in water to be electrocuted. Wet clothing, high humidity, and perspiration reduce resistance and increase your chances of being electrocuted.

Creating a Safe Work Environment

A safe work environment is created by controlling contact with electrical voltages and the currents they can cause. Electrical currents need to be controlled so they do not pass through the body. In addition to preventing shocks, a safe work environment reduces the chance of fires, burns, and falls.
You need to guard against contact with electrical voltages and control electrical currents in order to create a safe work environment. Make your environment safer by doing the following:
❑ Treat all conductors—even “de-energized” ones—as if they are energized until they are locked out and tagged.
❑ Verify circuits are de-energized before starting work.
❑ Lock out and tag out circuits and machines.
❑ Prevent overloaded wiring by using the right size and type of wire.
❑ Prevent exposure to live electrical parts by isolating them.
❑ Prevent exposure to live wires and parts by using insulation.
❑ Prevent shocking currents from electrical systems and tools by grounding them.
❑ Prevent shocking currents by using GFCIs.

Lock Out and Tag Out Circuits and Equipment

Create a safe work environment by locking out and tagging out circuits and machines. Before working on a circuit, you must turn off the power supply. Once the circuit has been shut off and de-energized, lock out the switchgear to the circuit so the power cannot be turned back on inadvertently. Then, tag out the circuit with an easy-to-see sign or label that lets everyone know that you are working on the circuit. If you are working on or near machinery, you must lock out and tag out the machinery to prevent startup. Before you begin work, you must test the circuit to make sure it is de-energized.

Controlling Inadequate Wiring Hazards

Electrical hazards result from using the wrong size or type of wire. You must control such hazards to create a safe work environment. You must choose the right size wire for the amount of current expected in a circuit. The wire must be able to handle the current safely. The wire’s insulation must be appropriate for the voltage and tough enough for the environment. Connections need to be reliable and protected.

Fixed, permanent wiring is better than extension cords, which can be misused and damaged more easily. NEC requirements for fixed wiring should always be followed. A variety of materials can be used in wiring applications, including nonmetallic sheathed cable (Romex®), armored cable, and metal and plastic conduit. The choice of wiring material depends on the wiring environment and the need to support and protect wires.

Esnek Kablolama ve Uzatma Kablolarının Tehlikelerini Kontrol Edin

Elektrik kabloları, bakım, taşınabilirlik, titreşimden izolasyon ve acil ve geçici güç ihtiyaçları için gereken esnekliği sağlayarak sabit kablolamayı tamamlar. Esnek kablolama, uzatma kabloları veya güç kaynağı kabloları için kullanılabilir. Güç kaynağı kabloları çıkarılabilir veya cihaza kalıcı olarak takılabilir.

Sık sık incelemenin zor olacağı, hasarın muhtemel olduğu veya uzun vadeli elektrik beslemesinin gerektiği durumlarda esnek kablolama KULLANMAYIN. Esnek kablolar bir yapının sabit kablolamasının yerine kullanılamaz. Esnek kablolar . . . olmamalıdır.
❑ run through holes in walls, ceilings, or floors;
❑ run through doorways, windows, or similar openings (unless physically protected);
❑ attached to building surfaces (except with a tension take-up device within 6 feet of the supply end);
❑ hidden in walls, ceilings, or floors; or
❑ hidden in conduit or other raceways.

Doğru uzatma kablosunu kullanın. Bir uzatma kablosundaki telin çapı, kablonun taşıması beklenen akım miktarıyla uyumlu olmalıdır. Akım miktarı, uzatma kablosuna takılı ekipmana bağlıdır. Akım değerleri (bir cihazın çalışması için ne kadar akıma ihtiyaç duyduğu) genellikle isim plakasında basılıdır. Bir güç değeri verilmişse, akım değerini bulmak için güç değerini watt cinsinden voltaja bölmek gerekir. Örneğin, 120 voltluk bir devreye takılı 1.000 watt'lık bir ısıtıcı yaklaşık 10 amper akıma ihtiyaç duyacaktır. Başka bir örneğe bakalım: 1 beygir gücündeki bir elektrik motoru yaklaşık 750 watt hızında elektrik enerjisi kullanır, bu nedenle 120 voltluk bir devrede en az yaklaşık 7 amper akıma ihtiyaç duyacaktır. Ancak, elektrik motorları başlatılırken veya durursa ek akıma ihtiyaç duyar ve isim plakasındaki akım değerinin 200%'sine kadarını gerektirir. Bu nedenle, motorun 14 ampere ihtiyacı olacaktır.

Uzatma kablosunun uzunluğu da kablo çapını seçerken dikkate alınmalıdır. Kablonun uzunluğu boyunca voltaj düşüşleri. Kablo çok uzunsa, voltaj düşüşü ekipmana zarar vermeye yetebilir. Birçok elektrik motoru yalnızca dar bir voltaj aralığında güvenli bir şekilde çalışır ve isim plakasında listelenen voltajdan farklı voltajlarda düzgün çalışmaz. Ampuller daha düşük voltajlarda (biraz daha loş) çalışsa bile, elektrik motorlarının gerekenden daha düşük voltajlarda düzgün çalışacağını varsaymayın. Ayrıca, elektrik motorları yük altında çalıştığında veya çalışmaya başladığında daha fazla akıma ihtiyaç duyarlar. Kablo çapı ne kadar büyükse, aletlere ve ekipmana zarar verebilecek bir voltaj düşüşüne neden olmadan kablo o kadar uzun olabilir. Sizi güvende tutmak için uzatma kabloları için topraklama yolu sağlam tutulmalıdır. Tipik bir uzatma kablosu topraklama sisteminin dört bileşeni vardır:

Cord Manufacturers chart on extension cords gauges, lengths, and amps.

Uzatma Kablosu Tanımları

• S – Esnek, genel amaçlı bir uzatma kablosudur.
• W – Uzatma kablosunun dış mekanda kullanıma uygun olduğunu belirtir.
• J – Uzatma kablosunun kaplamasında standart 300 volt izolasyon olduğunu belirtir. J'nin olmaması, kablonun yoğun kullanım için daha kalın, 600 volt izolasyona sahip olduğunu gösterir.
• P – En çok paralel bağlanması gereken klima güç kablolarında ve ev tipi uzatma kablolarında bulunur.
• T – Vinil termoplastik kılıflı bir uzatma kablosu üzerinde sergilenmektedir.
• E – Termoplastik elastomer kauçuk ceketli bir uzatma kablosunda gösterilir. Bu bazen TPE olarak yazılır.
• O – Uzatma kablosunun yağa dayanıklı olduğunu belirtir (İki OO, iç ve dış kılıfın yağ geçirmez olduğu anlamına gelir)

Control Hazards of Exposed Live Electrical Parts: Isolate Energized Components

Electrical hazards exist when wires or other electrical parts are exposed. These hazards need to be controlled to create a safe work environment. Isolation of energized electrical parts makes them inaccessible unless tools and special effort are used. Isolation can be accomplished by placing the energized parts at least 8 feet high and out of reach, or by guarding. Guarding is a type of isolation that uses various structures—like cabinets, boxes, screens, barriers, covers, and partitions—to close-off live electrical parts.

Control hazards of shocking currents

Ground circuits and equipment. When an electrical system is not grounded properly, a hazard exists. This is because the parts of an electrical wiring system that a person normally touches may be energized, or live, relative to ground. Parts like switch plates, wiring boxes, conduit, cabinets, and lights need to be at 0 volts relative to ground. If the system is grounded improperly, these parts may be energized. The metal housings of equipment plugged into an outlet need to be grounded through the plug. Grounding is connecting an electrical system to the earth with a wire. Excess or stray current travels through this wire to a grounding device (commonly called a “ground”) deep in the earth. Grounding prevents unwanted voltage on electrical components.

Topraklama, açıkta kalan parçalardaki istenmeyen voltajlar tarafından üretilen akımlar için bir yol oluşturur. Bu akımlar, enerjili ekipmana dokunan birinin vücudundan geçmek yerine topraklama yolunu takip eder. Topraklama, arızalı ekipmandan dolayı şok almayacağınızı, yaralanmayacağınızı veya ölmeyeceğinizi garanti etmez. Ancak, olasılığı büyük ölçüde azaltır.

The use of GFCIs has lowered the number of electrocutions dramatically. A GFCI is a fast-acting switch that detects any difference in current between two circuit conductors. If either conductor comes in contact—either directly or through part of your body—with a ground (a situation known as a ground fault), the GFCI opens the circuit in a fraction of a second. If a current as small as 4 to 6 mA does not pass through both wires properly, but instead leaks to the ground, the GFCI is tripped. The current is shut off.