Loose neutral connection?

Old 03-21-04, 04:18 PM
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Loose neutral connection?

What is a loose neutral connection?
Old 03-21-04, 04:38 PM
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Electricity needs a complete path back to the source. In home systems there are generally two hot wires and one neutral. The neutral provides the return path back to the source.

The wiring that runs to your 120 volt lights and electricial receptacles uses two wires. One wire (usually black) is connected (through a fuse or circuit breaker) to one of the incoming hot wires. The other wire (white) is connected to the neutral wire going back to the source.

A loose neutral connection can be a neutral wires that is not tightly connected at any point in your electrical system.
Old 03-21-04, 06:36 PM
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Think of the transformer on your pole as a 240 volt coil of wire. The center point of it is tapped and grounded so that you have a mid-point reference (ie-120 volts from either leg to the center tap ). This is the neutral. Any appliance that you connect off of either leg now has a120 volt reference back to this center tap. (Don't think about 240 volt loads like AC and clothes dryers right now, they're not effected).

Assume you have a small load (a light bulb) on one leg drawing an amp. On the other leg you have a microwave oven drawing 10 amps. As long as the neutral is sound, there is a reference to the midtap of the transformer and each device has 120 volts across it.

Now assume you lose your neutral connection. Instead af having a 120 volt reference to the mid-tap, there is now 240 volts across the two loads that must divide according to Ohms Law. The light bulb has 10 times the impedance that the microwave oven has; therefore, 10 times more voltage will be dropped across the bulb as the oven. The bulb burns out prematurely and the oven doesn't want to work.

The easiest way to check for this without a volt meter is to plug in a heavy load 120 volt appliance (microwave, vacuum cleaner, etc.) with all the lights on in the house. If some get dim, and others get brighter, you've got a neutral problem.

The key here is the lights getting brighter. Just dimming could indicate a loose connection.

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