Residential outlet

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rjlight

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I had a lady call me about an outlet that will not run her vacumn cleaner. I took it apart and now is properly grounded, has correct polarity, shows 121 volts with meter reading, runs lights and a radio, but will not run anything with a motor such as vacumns, sanders, drills, etc. It does not trip a breaker but any motored device just barely hums. Besides voltage drop what am I missing? And what can I do to correct?

Thank You, Raymond

Not that it matters but it is an older house (60 years) with BX cable.
 
rjlight said:
Besides voltage drop what am I missing? And what can I do to correct?
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Sounds like voltage drop is the issue. Can you determine how long the circuit is?
 
Also, can you determine what size of wire feeds the outlet, and whether that size of wire is used for the entire length of the run? One more thing: can you safely check for voltage at the outlet, with the vacuum cleaner (or other motor load) running?
 
did you check the connections in other receptacles in the circuit? have your helper turn the motor on and measure the voltage in the panel feeding that circuit and see what you have for a voltage drop.
edited it to make it more clear
 
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rjlight said:
I had a lady call me about an outlet that will not run her vacumn cleaner. I took it apart and now is properly grounded, has correct polarity, shows 121 volts with meter reading, runs lights and a radio, but will not run anything with a motor such as vacumns, sanders, drills, etc. It does not trip a breaker but any motored device just barely hums. Besides voltage drop what am I missing?
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Sound like you have high resistance in the line. At a receptacle or where the wires are twisted togather in a junction box it is loose and arced.There will be a carbonization at the arced spot that will act just like a resister in the circuit.

The easies way to find the problem is to figure out which circuit you are dealing with and work away from the panel. First make sure the connection is good at the breaker and neutral bar and then go to what appears to be the first receptacle fed by this circuit.
 
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I also believe you have a loose connection. There can be enough current getting thru to read 120 volts but whenthe vacuum is plugged in I bet the voltage drops to zero or thereabout.
 
It' easy (and cheap) enough for Ray to keep the meter on the circuit while adding loads.
 
Classic symptoms of a loose connection, probably a loose neutral. I would start by having a peek in the panel at the neutral (grounded) wire of this circuit.
 
Sure proof is to pop a twofer in the recep, and plug your meter in. Just watch those volts plunge when you plug in the vacuum.

They'll drop for the light too, but not by so much.

By metering from ground to the twofer you can determine if it's a neutral or hot wire with the high resistance element.

First off leave the vacuum humming and check the volts on the panel on off the breaker, thus eliminating the panel and breaker. And look very closely where the neutral goes to the bar, as the problem could be in the hot or neutral circuit elements.

After that if its not a loose screw (more likely) or bad wirenut / pigtail / whatever (and it could be anywhere in the line from the panel to the recepticle, in either the hot or neutral), its failed cable. That could be an ugly job...
 
Ode to the internet!

Ode to the internet!

& if your spring for the Ideal Tool, Be sure to shop around! It's could be a $100.00 less :rolleyes: .
 
I agree with the bad connection. That's the first thing I thought of. I've never used a gadget to try to find this kind of thing, maybe there's stuff that's supposed to do that nowdays but I've never seen it. What I do is find the path of boxes in the circuit and check them.
 
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