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Low Voltage on Home Outlet

12/01/2010 1:06 PM

My home electrical AC outlets (USA) run three wires - black, white and bare copper (ground). One particular outlet does not power things that I plug in. I have removed the plug receptacle and tested voltage across the black and white wires. The multimeter consistently reads 90 - 95 volts (other outlets typically read 120V, as I would expect). Also, voltage across black and bare wire reads 120V.

Seems to me that a short would produce symptoms elsewhere in the circuit, or trip a breaker. What would cause this outlet to output a consistent low voltage?

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#1

Re: Low Voltage on Home Outlet

12/01/2010 1:47 PM

Loose connection in the junction box, or back at the receptacle the power is being daisy chained from.

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#7
In reply to #1

Re: Low Voltage on Home Outlet

12/02/2010 6:20 AM

Right on!!!

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#2

Re: Low Voltage on Home Outlet

12/01/2010 1:55 PM

I agree with charsley99 .

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#3

Re: Low Voltage on Home Outlet

12/01/2010 2:21 PM

And since you get the correct reading from the Hot-to-Ground connection, I'd venture to say it's a bad Neutral connection in the previous junction. Take a look at the layout in your room(s) and plot a logical run back towards the breaker panel. Whichever outlet would be the previous one in that run is the likely culprit. If the power for your outlet is coming from a wall switch, look at the neutral wire-nuts in the switch box.

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#4

Re: Low Voltage on Home Outlet

12/01/2010 3:38 PM

Since you have only one outlet that does not provide full voltage across hot and neutral then this outlet is a branch end. So unless you have an illegal hidden junction box or the very unlikely broken neutral wire, the bad neutral connection is happening at the outlet upstream of this one going back to the breaker distribution panel. This outlet might be on the other side of the wall or along the wall in the direction to the breaker panel.

A common problem that fits your symptoms was that at one time outlets were permitted to have spring loaded knife edges to make a connection to a bared wire. Over time these springs would fatigue and stop making a good connection. This design did save an electrician a little time in wiring a house. But over time these weak springs could and have started more an electrical fire.

If you have a hidden junction box though, then you will likely have to remove some sheet rock.

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Re: Low Voltage on Home Outlet

12/01/2010 9:01 PM

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#6

Re: Low Voltage on Home Outlet

12/02/2010 4:19 AM

Hi Folks, Since the multi-meter reading shows low voltage, drawing virtually no current, could it be that the attachment of the ground and one of the other wires has been reversed? Trace wires as much as possible to confirm correct connections.

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#8

Re: Low Voltage on Home Outlet

12/02/2010 12:07 PM

Great suggestions. I'll report back when I have a chance to chase the wires.

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#9

Re: Low Voltage on Home Outlet

12/02/2010 3:39 PM

It's very good you have copper wiring in your home!

I've been called to many homes and businesses with aluminum wiring installed in the early to the late 1970's when it was allowed to substitute as a cheaper replacement for proper copper wiring. This greatly helped electrical contractors to save money as aluminum was roughly half the cost of copper.

It then was immediately withdrawn and not available to purchase in electrical supplier's warehouses anymore, after it was proven that homes and businesses were catching on fire and burning down, including losses of life, due to faulty aluminum wiring installations and practices at that time.

Aluminum wire has a nasty habit of developing a whitish, powdery aluminum oxide residue on or about it's exposed to air contact area, due to it's chemical characteristics. For example, when the thermoplastic insulation is removed by 'stripping'.

This aluminum oxide develops over time while being exposed to the oxygen in the air, and may eventually become resistive when connected to joints or device connections, if not properly protected against exposure to the air, and more critically, when joined together with differing dissimilar metal at an electrical connection point. These connection points can get very hot, and start fires.

Something to ponder - Loupy.

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#10

Re: Low Voltage on Home Outlet

12/05/2010 1:04 AM

Abasile60,

Your multimeter is a high-impedance device---in other words, it has a very low load on the circuit being tested. What you are reading is typical of a circuit in which the "hot" and "ground" leads are properly connected and the "neutral" is open upstream. Inductive or capacitive coupling are giving a circuit which your meter "sees" as low voltage between the "hot" and "neutral". If you were to connect a load to the receptacle in question (such as a portable lamp), I am sure that the voltage measured between the "hot" and "neutral" would go to zero.

--JMM

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#11
In reply to #10

Re: Low Voltage on Home Outlet

12/05/2010 7:41 AM

I liked your comment.

GA from me.

You wrote:-"f you were to connect a load to the receptacle in question (such as a portable lamp), I am sure that the voltage measured between the "hot" and "neutral" would go to zero."

Or the faulty connection(s) might just get very, very hot if something is plugged in, so don't do it!! A possible source of fire cannot be completely ruled out either......

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abasile60 (1); Andy Germany (2); Anonymous Poster (2); charsley99 (1); jmueller (1); JRaef (1); Loupy (1); lyn (1); redfred (1)

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