Electricity for the 4-H Scientist

LESSON NO. B-4

Credit Points 3

MAKE A TROUBLE LIGHT.

A handy piece of equipment in the home and on the farm is a heavy-duty extension cord with a shielded light and a side outlet on it. When you want to work on the car or tractor in the yard at night, the trouble light is better than a flashlight. You can use it both for light and as an extension cord. It is safer than matches or a lantern, especially around the garage or barn.

It is easy to make a trouble light, and it gives you good practice in electrical work. Of course you can buy one, but you wouldn't have the fun of making it nor would it suit your needs. Trouble lights are not for permanent use—they're for emergency use and to provide light or electricity in places where they are seldom needed. When you find a trouble light being used as permanent wiring, that's the place to install an outlet.

What Size Cord?

Choose the right kind of cord. What length will be best for your various uses? A cord too long may be bothersome to use and store. What will be the heaviest load you are likely to put on the cord, in amperes? Check appliances you may want to connect to it. No. 16 wire can carry 10 amperes safely for a distance of 50 feet, while No. 18 can carry only up to 7 amperes for a distance of 40 feet. You'll want a "hard service" cord, called S, ST, or SO-type cord by electricians. Junior hard service cords, known as SJ, SJT, or SJO, are fine for lighter duty.

Cord, Plug and Guard

A rubber-handled socket should be used for safety and to withstand hard knocks. It should have a switch on it, preferably a push switch in a recess in the handle.

The connector or attachment plug should be of rubber or solid plastic and have a metal cord grip fastened to it. This grip will hold the cord firmly and prevent strain on the terminal connections.

Finished Trouble Light

Get a good lamp guard. If the wire is too light, it may bend and break the bulb when hit or dropped. For the lamp itself, get a rough service lamp. An ordinary lamp won't last long with rough usage.

How to Make the Trouble Light

Tools Needed:

Your 4-H electrician's kit or screwdriver, knife and soldering iron

Materials Needed:

1. About 20 feet of 2-wire, No. 16 heavy duty (hard service)

2. A rubber-handled socket with switch and a side outlet

3. A shielded lamp guard

Materials Needed

4. A good connector plug cap, preferably with a clamp-type grip for the cord

5. A rough service lamp bulb

6. Solder and flux

Steps to Take:

1. Remove about 2 inches of the outer covering of cord at one end.

2. Separate the wires and cut away the filler material.

3. Remove 3/4 inch of the conductor insulation from the end of each wire and tightly twist the strands together to form a firm conductor. Be careful not to cut any of the fine wires. Ends may be soldered.

4. Slide the plug in position on the cord.

5. If there is no cord grip, tie the underwriters' knot (Figure 1). If there isn't room enough, make an "S" loop by passing the wires around the prongs before fastening them to the terminal screws as explained in the next step.

6. Loop the bare part of the wire around the screw in the direction the screw is turned to tighten (clockwise direction). This will prevent the wires from being forced out from under the head of the screw as it is tightened. Now repeat with the second wire, wrapping it around the other prong of the plug.

Connecting the socket.

1. Separate the parts of rubber-handled socket (Figure 2).

2. Prepare the other end of the cord as in steps 1, 2, and 3 above.

3. Insert the cord through the rubber handle and socket guard.

4. Tie the holding knot (underwriters' knot) as explained in Step 5.

5. Connect wires to terminal screws and assemble the rubber-handled socket.

6. Screw in the rough service lamp and test your cord.

7. Put the shielded lamp guard on the socket and tighten the holding clamp until it is firmly in place. You are now ready to use or demonstrate your trouble light.

8. After you've made your trouble light, decide on a good place to keep it where it will be handy for use. Loop it carefully and hang it over a wooden dowel rather than a nail. It will last longer.

Figure 1 Tying an Underwriter's Knot

Figure 2 Disassembled Light

What Did You Learn?

(Underline correct answer)

1. A Junior Hard Service Cord is known as an (SO-Type) (SJO-Type) cord.

2. You disconnect a cord by (jerking it from the socket) (grasping plug and pulling it out).

3. Brass sockets are unsafe because (they break too easily) (the exposed metal can cause short circuits).

4. Rubber-covered cord is safer for emergency cords than fabric because (it will stretch) (it will insulate and protect the wires inside).

5. In a trouble light (any kind of bulb will do) (a rough service bulb is best).

Ideas for Demonstrations and Exhibits

1. Show how to make your trouble light and a method of storing it.

2. Show a safe trouble light, and an unsafe trouble light with danger points marked.

3. Show cutaway pieces of different types of cord.

For More Information

Ask your power supplier, county highway engineer, police official or leader to tell you about various types of portable emergency lights and their uses.

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