Electrical Wiring - corrosion, cracking and resistance.

In summary, in a conversation about the cause of house fires, it was discussed that corroded or cracked wiring can contribute to the fire. This is due to the change in resistance caused by the corrosion and the reduced cross-sectional area of the wire. Using Joule's Law and the formula for resistance, it can be determined how this change in resistance can lead to the wire igniting and causing a fire.
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Homework Statement


Been racking my brains over this one and I'm stuck maybe someone here can help me. I'm doing physics through distance education at high school and its very difficult.

"In house fires the wiring is often cited as the cause of the fire. Often this wiring is partially corroded through or cracked. Explain why this may be a contributing factor in causing the fire by referring to what you have learned about resistance."

Homework Equations


n/a

The Attempt at a Solution



I honestly have no idea at all how the crack or corrosion could cause a change in resistance and lead to a fire. I have learned that the following factors influence resistance:

1 - length
2 - type of material
3 - cross sectional area
4 - temperature

As well as this I'm aware of Ohm's law...

I'm thinking it may have something to do with the temperature but I'm really just pulling ideas from nowhere.

Any help would be very very much appreciated.

Thanks
 
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  • #2
Corrosion would have the effect of changing the material (oxidization?), and thus the resistance of the wire.
Cracking or crushing or bending the wire, can change its cross section area.
 
  • #3
ahh okay. thanks :D
 
  • #4
To be more precise, both in fact, have the same effect. They reduce the cross-section area of the conducting part of the wire (The oxides that form as a result of corrosion are insulators).

Use Joule's Law (Power dissipation in a resistor), and the formula for resistance in a wire to find how this effect may cause the wire to ignite.
 

1. What causes corrosion in electrical wiring?

Corrosion in electrical wiring is typically caused by exposure to moisture, chemicals, or other environmental factors. This can weaken the protective coating on the wires and lead to rust and decay, which can increase resistance and hinder the flow of electricity.

2. How can I prevent corrosion in my electrical wiring?

To prevent corrosion in electrical wiring, it is important to use high-quality, corrosion-resistant materials, such as copper or aluminum wires with a protective coating. Proper installation and regular maintenance can also help prevent moisture and other contaminants from damaging the wiring.

3. What are the signs of cracked electrical wiring?

Some common signs of cracked electrical wiring include flickering lights, frequent tripped circuits, and burning smells. In some cases, you may also notice visible cracks or frayed wires. If you suspect cracked wiring, it is important to have a professional inspect and repair it as soon as possible to avoid potential hazards.

4. What causes electrical wiring to crack?

Electrical wiring can crack due to a variety of reasons, such as age, wear and tear, poor installation, or exposure to extreme temperatures. Overloading circuits, using incorrect wiring sizes, and using low-quality materials can also contribute to cracking and weakening of the wires.

5. How does resistance affect electrical wiring?

Resistance in electrical wiring can cause a decrease in the flow of electricity and can lead to overheating, which can be a fire hazard. High resistance can also cause lights to dim or flicker and appliances to malfunction. It is important to regularly check for and address any issues with resistance in electrical wiring to ensure safety and proper functioning.

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