Rats and Wires: A Science Project

Complexity level:	8
Project cost ($):	50
Time required:	1 day to prepare, 2 days for the science project experiment
Material availability:	Easily found
Safety concerns:	Live electrical wires gnawed by rats can become exposed and cause short circuits or electrocution. Ensure that no flammable materials or gasses are within reach, and perform this experiment in a well ventilated laboratory under the care of a qualified adult. Disconnect ALL electrical connections before handling the cables. Ensure that protective gear (insulating gloves)/goggles are used. Rats should be handled with care as they bite!

Hypothesis

Rats prefer to chew on telephone and PVC wires.

Overview

Rat nuisance

Rats can be a nuisance in many ways. They enter homes in search of food and shelter and in the process, damage our food and furniture. However, one of the biggest problem caused by rats is when they chew out the electrical wiring in our homes. The damages caused by the rats can be very expensive and sometimes lead to fires and a loss of lives!.

Rats have very sharp teeth that grow continuously. This teeth can even cut through soft metals. This is the reason why it is better to use stainless steel conduits instead of plastic conduits for our wires and cables. Rats also cause problems by biting the electrical wiring in cars, trucks and trailers. The damage can sometimes be very difficult to locate, resulting in large repair bills!.

Among the things we can do to prevent rats from entering our homes, are to cover any holes larger that 10mm. We should also clear away things that attract them to our homes such as stacked wood or thick foliage. Leaving food outdoors will attract rats and should be avoided.

Scientific Terms

Electrical wiring, appliance wiring, stainless steel conduits, plastic conduits, coaxial cables, 3 core wires

Materials

The materials required for this science fair project:
- 3 rats
- a rat trap (cage-type)
- telephone wire
- Coaxial cable
- Red PVC wire
- Black PVC wire
- A 3 core power cable
- Speaker wire
- Rubber mat
The equipment to which the wires are usually connected to should also be used for this science experiment. For example, for the telephone wire, we will need the use of the telephone and access to the wall-socket (see step 3 of our procedure).

Procedure

1. For this science fair project, the independent variable is the type of wire used - telephone, coaxial, red PVC, black PVC, a 3 core power cable and speaker wire. The dependent variable is the extend of damage done by the rats. This is determined by inspecting the wires for bite marks. The constants (control variables) are the number of rats in the cage, amount of time the cables are left in the cage and the number of days during which the rats are starved.

2. Three rats are placed in a cage without food for 1 day. On the second day, tall of the wire types are passed through the grills of the cage and left there for 24 hours. Ensure that the wires are not connected to the equipment/mains supply. The next day, the wires are removed from the cage and inspected for bite marks. The results are recorded in the table given below.

3. On the third day, the wires are connected to the equipment (to which they are normally connected) and the equipment turned on, to allow current to pass through them. The wires are then passed through the grills of the cage and left there for 24 hours. The cage is placed on a rubber mat to prevent electrocution. The next day, the wires are disconnected and removed from the cage and inspected for bite marks. The results are recorded in the table below.

Results

It was observed that the rats preferred to bite the telephone cables and the PVC wires with or without current flowing in them.

Condition	Telephone wire	Coaxial wire	Red PVC cable	Black PVC cable	3 core cable	Speaker wire
Without current	√	X	√	√	X	X
With current	√	X	√	√	X	X

√ - bitten by the rat, X – no bite marks

Conclusion

The hypothesis that rats prefer to bite telephone and PVC wires is proven to be true.

A large percentage of fires in buildings in the USA are believed to be caused by rodents like rats, mice and squirrels. Because their teeth are constantly growing, rats need to chew constantly. When rats chew on power cables and expose the copper cores, they risk electrocution. The sparks emitted can ignite a fire if there are any flammable materials in the vicinity.

Also consider

Would your results differ if this science fair project were to be repeated using different types of animals like mice or squirrels?

The science project can be repeated with different types of wires – eg Teflon coated wires.

References

How to stop rats from chewing house wiring - http://www.ehow.com/how_5712971_stop-rats-chewing-house-wiring.html

Rodents and fires - http://www.homeinspectionsbyjerrykellyiii.com/RodentsFires.html

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