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The Importance of Electrical Circuit Polarity

	©Copyright Dave Rongey - About Me - Summary: How to Identify and Repair Reverse Polarity: Electrical Safety and Proper Circuit Polarity – Polarity has to do with the flow of electricity. As the name implies, polar has to do with direction, north pole, south pole, and this is related to magnetism which is the influencing force or flow or direction, which takes us right back to polarity.

Reverse Polarity and How to Fix It

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Electrical Question: I need your help on something. I know what reverse polarity is – when a receptacle is wired with the hot and neutral wire feeds attached to the opposite screws that they should be attached to.

I want to know why this is bad. My understanding is when a receptacle is wired this way it will send power to the lamp or radio, etc in the reverse direction that was intended. But, why is this bad?
What negative effect does it have?

Thank you for your help in this,
Randy

This electrical question came from: Randy , a Homeowner from Alexandria , Virginia.

Additional Comments: very good, helpful.

Dave’s Reply:
Thanks for your electrical question Randy.

How to Identify and Repair Reverse Polarity

Electrical Safety and Proper Circuit Polarity

The Importance of Electrical Polarity
Randy, polarity has to do with the flow of electricity. As the name implies, polar has to do with direction, north pole, south pole, and this is related to magnetism which is the influencing force or flow or direction, which takes us right back to polarity.
Polarity and Electrical Devices

• It used to be that polarity was not such a big concern, especially when using standard incandescent light bulbs with nothing more than a sealed vacuum enclosure with gas and a carbon wire filament which was not polarity sensitive, the light bulb would light if the power flowed in either direction, it just needed power to make the filament glow. With more modern electrical devices, we have a third wire for the ground and more and more devices have electrical circuits and components that are definitely polarity sensitive.
• You may even notice that one of the straight blades of the 120 volt outlets is larger that the other, and the same is true for the plugs found on many cords of electrical appliances. This is because there is a specific polarity that is needed for the specific circuit components.
• The hot wire of a 120 volt circuit is an ungrounded conductor while the neutral wire is a grounded conductor, both being current carrying conductors which is why they are insulated.
• The third wire being the ground wire may be uninsulated because it is a non-current carrying conductor which is used as an equipment safety which is attached to the frame or enclosure of  the electrical device. This grounded conductor has a direct path of least resistance to the main ground source where it sends voltage in the case of a failure, which is designed to quickly cause the circuit protective device to trip and de-energize the circuit and protect it from damage.
• Some electronic devices may actually be damaged if they are plugged into an outlet that has reverse polarity. So to summarize this it is well to understand that with today’s electrical circuits it is best to make sure the polarity is correct.

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