Electrical Safety Considerations

Before reading this topic, you must first understand the basic electricity-1 topic for best results. This topic will point out some safety concerns that you need to be aware of. Take some time and read this topic, it is VERY IMPORTANT. This topic can not possibly address all safety precautions, and is not intended to be all inclusive. These are just some of the representative safety issues.

Hot Truck Chassis & Death

The 12 volt battery circuits on a truck will not kill you, so touching active (hot) truck circuits isn't dangerous. A hot truck chassis, on the other hand, can kill you. When we talk about a hot truck chassis here, we are referring to 110Vac house current coming into contact with the truck chassis. For example, you could be using an old drop light, and a frayed part of the cord transfers 110Vac to the entire truck chassis. Will the 110Vac circuit breaker trip because of the chassis contact? Probably not, since the truck is sitting on rubber tires, and rubber is a good insulator.

Most garage floors are damp concrete, which makes for a good conductor and ground path. If you stand on the damp concrete and touch the hot truck chassis, your body becomes the 110Vac load resistance, which could result in a lethal shock. If it isn't lethal, it will hurt a lot, and could cause you to be nervous and jittery for quite a long time afterward. You should always seek medical attention after a serious shock, because you heart beat could become erratic or stop completely without warning.

The best way to prevent this situation, is to attach a heavy grounding strap to the truck chassis. With the grounding strap attached, the above frayed cord situation would result in tripping the 110Vac circuit breaker. It is much better to have the grounding strap trip the circuit breaker, instead of your body. In fact, your body would not trip the breaker even while you are being shocked to death. It only takes about 1/100 amps passing through your heart to kill you. That drop light circuit breaker is probably rated at 15 amps. Therefore, the circuit breaker could supply 1500 times the amount of current that is required to kill you.

Fortunately, not all is gloom and doom here. Your leather or rubber shoes offer some degree of resistance between you and that damp concrete. To maximize the current flow through your heart, current must flow from one arm to the other arm, or from your left arm to either leg. Due to the insulating quality of your shoes, you most likely will not die when touching a hot chassis, but don't count on it. If your feet are wet or sweaty, then the insulating property of your shoes is seriously compromised.

Remember one thing, if you are touching the hot truck chassis with one hand (insulated shoes are protecting you) and then you grab a metal cased electric power tool with the other hand (most electrical power tools have the case grounded for safety), the safety feature of the power tool may have just killed you. You have now placed 110Vac between both hands, and your heart now gets maximum and possibly lethal current flow.

There is one other hot chassis situation caused by mother nature. If you are touching a truck chassis when lightning strikes that vehicle, you become the lightning rod. You provide the path to ground for the lightning strike. Your rubber shoes will provide little protection since the high voltage of the lightning strike will jump right across your rubber shoes and fry you in the process. It is not a good idea to be crawling into and out of your truck while lightning strikes are a threat.

Eliminate Accidental Shorts and Burns

The main battery cables run directly to the starter motor, with no fuses involved. Therefore, before working on the starter, you must disconnect one of the battery cables first. Any electrical repairs which involve unfused circuits, requires that the battery be disconnected. If the electrical part to be serviced has a fuse or circuit breaker, remove the fuse or circuit breaker before servicing that part.

If a wrench contacts the unfused circuit and ground at the same time, then sparks will fly and the wrench will get very hot very quickly. This can result in burned insulation of the associated wires due to the excessive heat generated by the short circuit current. It can also result in burns to your hand if you don't let go of the wrench before it gets hot. The arcing action can also damage surrounding surfaces or parts, and sometimes the wrench actually spot welds in place.

Always disconnect the battery before servicing unfused circuits. Always!

Gold Jewelry Dangers

Another danger while working around electrical parts, is the wearing of gold jewelry. As you may know, gold is one of the most perfect conductors. Imagine what happens if your gold ring completes the path from the hot side of the battery to ground. The gold ring passes massive current, heats up red hot in a second, and begins burning its way through your ring finger. And guess what? You can't just grab it and pull it off, because it will burn the fingers that you grab it with!

The same thing could happen to other gold items of jewelry. A gold wrist bracelet dangling near an unfused battery circuit can do the same thing to your wrist that the ring can do to your finger. Jewelry and electrical repairs do not mix.

Cuts From Broken Light Bulbs

Have you ever broken a bulb trying to get it out of its socket? Usually, the glass separates from the brass base of the bulb, but sometimes the bulb will crush, resulting in cut fingers. Don't use your unprotected fingers to remove stubborn light bulbs.

Battery Dangers

Batteries present several different forms of danger. First, they are very heavy and can cause wrenching of the back if you are not careful. They also contain acid, which can cause eye injury if splashed into the eyes. The battery acid will also eat holes in your clothes. The battery is also the source of power for the burn situations discussed above. Any conductor which shorts between the two battery posts, could become a flesh burning branding iron.

Batteries can also become bombs. Let me say that again, batteries can also become bombs. In basic electricity, we explained that batteries generate hydrogen gas while being charged. If a battery is being fast charged, then this explosive gas is generated in large volume. All it takes is for a spark to occur near the battery vents, and presto, all of that hydrogen gas inside the battery explodes.

Lets take a typical explosive situation. The truck battery is dead, so you place it on fast charge. A half-hour later you try to start the truck, but there is a loose battery connection at the battery post. You now have hydrogen gas venting from the fast change, and a spark from the loose battery connection which is right next to the battery vents. Never stand near any battery while cranking the engine.

When the battery explodes, it expels several projectiles. First it splinters the battery case and all those splinters become projectiles which can penetrate your body and eyes. Right behind the case pieces comes the acid which is also not good for your eyes. And right behind the acid comes the lead plate pieces. Lead poisoning is a real threat, so imagine a large number of lead particles soaked in battery acid and embedded throughout your body and eyes.

Another situation where batteries can explode is during jump starts. If you put the jumper cables on backwards, positive to negative and negative to positive, you now have a battery war on your hands. The two batteries are fighting which results in excessive currents, hydrogen gassing, and sparks when you remove the reversed jumper cables. This has all the ingredients for a battery explosion.

There are other situations for battery explosions, including fast charging of frozen batteries. Just remember, batteries are energy storage devices. Make sure that you do not release this energy in unexpected ways.

Burns From Hot Motors and Light Bulbs

Electrical things get hot under normal conditions. This heat is a result of resistance losses inside the device. For example, a truck starter motor gets very hot if you crank the engine for a long time. If you reach out and touch that motor right after extensive cranking, you may leave a layer of your skin on that motor, or you may have finger blisters before you know what happened.

When there is a problem, the current can be excessive, and the resultant heat can be much greater than normal. The electrical device can get overheated, and the wires connecting to the device can also get very hot.

Light bulbs can also get very hot while in use. So don't just reach in and try to remove a lighted light bulb without some hand protection.

This topic in no way covers every electrical safety consideration that you should make. Your own common sense must also come into play for adequate safety protection for situations not covered in this topic.

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