Power loss at outlet

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  #1  
Old 08-26-18, 03:55 PM
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Power loss at outlet

Here's a problem I never heard of before.

I installed a home exterior outlet and security light by tapping into an existing 15 amp circuit (junction box installed inside my garage). I'm experiencing power loss at the outlet. For example, when I plug my electric drill into the new outlet, I'm only getting about 20% power. Also, the security light is dim and flickers.

The connections are basic and straightforward. I've replaced the light, the switch and the outlet, sequentially testing each time, with the same results. All previously installed lights and outlets on this circuit before and after the junction box work fine with full power.

Seems like the problem is in the outlet. Could I have gotten 2 defective outlets in a row? Is this even plausible? I thought with electricity, either you have the juice or you don't. What are possible causes of a power loss?

Thanks!
 
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Old 08-26-18, 04:02 PM
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How are you measuring that it's 20% power? Your outlet doesn't appear to be WR rated. (Weather Resistant).
 
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Old 08-26-18, 04:03 PM
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Did you have a black and a.white connected to the switch? If so you do not have a neutral for the device and are wiring in series with the bulb.
 
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Old 08-26-18, 04:36 PM
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Look for loose wire nuts at outlet, switch or last working outlet/ switch in circuit.
 
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Old 08-26-18, 09:31 PM
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The light gets power from the outlet. The switch is wired with the incoming black and the outgoing black. The white goes directly from the outlet to the light.
 
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Old 08-26-18, 09:42 PM
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All the outlets have power. The new one (i.e., the one in question) has diminished power. I've tried two different outlets, all wire nuts are secure each time.
As far as '20%', that is just a guess to illustrate how much the power is diminished. When I plug in my electric drill, it does not go full speed. I'm guessing about 20% of full speed.

I think I will try another (new) outlet. The only explanation I can think of is maybe someone returned two defective outlets (to Home Depot), and they inadvertently got put back on the shelf, and I ended up buying them. I'll also check the junction box, even though all the outlets and lights downstream from it are working fine.
 
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Old 08-26-18, 11:16 PM
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Disconnect the power-in wires at the problem receptacle and using an analog multimeter measure between black and white.
 

Last edited by ray2047; 08-27-18 at 01:45 AM.
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Old 08-27-18, 03:15 AM
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The receptacles outside should be gfi protected and have a bubble cover.
 

Last edited by pcboss; 08-27-18 at 03:54 PM.
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Old 08-27-18, 05:45 AM
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Try connecting the outlet using the screw connections and not back stabbed.
 
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Old 08-28-18, 03:25 PM
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I replaced the outlet with another brand new outlet (this is the 3rd one I tried). I wired it with the screw connections instead of back stabbing. Still the same problem persists.

I forgot to pick up a volt-meter at Home Depot. But I thought now for sure the problem has to be in the new junction box. A visual inspection of the junction box revealed no loose wiring. The wiring was correct and the connections were tight. Nevertheless, I remove the wire nuts and reconnected to doubly ensure a tight connection. Still the problem persists.

Like I said, there is full power on all the outlets downstream and upstream from the junction box -- except for the new line I put in. Any other theories as to the cause of power loss? Otherwise, I see no choice but to return to Square 1 and start over. Hate to do that without knowing what the problem is...
 
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Old 08-29-18, 04:59 AM
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You need to verify AC voltage in the junction box where the outside circuit is connected. While you can SWAG the AC voltage level by speed of your drill or brightness of a light, buy an inexpensive analog multimeter ($10-15). Disconnect the outside circuit in the junction box and measure AC voltage between black and white wire. If you measure 120 vac, the voltage up to the junction box is good. Reconnect outside circuit and measure AC voltage at outside outlet (screw terminals containing wires from junction box). If you measure 120 vac, the voltage up to the outlet is good. If you measure less than 120 vac, the wire from the junction box to the outlet is defective and needs to be replaced. If the AC voltage at the light is less than 120 vac, these wires have poor connections in the outside outlet box.
 
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Old 08-29-18, 05:02 AM
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Do you have a continuous black wire path from the working receptacle inside, out to a gold terminal of the new receptacle outside?

Do you have a continuous white wire path from the working receptacle inside, out to a neutral (silver) screw of the new receptacle outside?

IThere is a slight possibility you will have to go back to square one to achieve yes answers to the preceding two questions.

There is a moderate possibility that the light got wired into a series subcircuit with the receptacle which is incorrect and which would cause the symptoms you reported.

Perform your voltage measurements as described previously with an incandescent light plugged into the new receptacle and switched on, or with your drill plugged in with the trigger pulled.
 

Last edited by AllanJ; 08-29-18 at 05:23 AM.
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Old 08-29-18, 06:58 AM
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The problem is not any of the devices (receptacles or switches). The wiring is hooked up wrong as some devices are in series rather than parallel. We'll need to see the wiring in the junction box from which you extended power and understand what that junction box is connected to.

A common way for this error to happen is to extend power from a light switch loop or a 3-way lighting switch loop.
 
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Old 08-29-18, 01:29 PM
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Here's a diagram of the wiring (note: the light grabs power from the new outlet, so it is not shown)
 
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Old 08-29-18, 02:32 PM
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Try this next. Unhook all of the wiring for the light, label and tape their ends, and leave them hanging loose while leaving the black and white wires bringing power to the new receptacle in place. Then verify that the receptacle is live or is not live.

Where the wires coming from the inside junction box and going through the wall to the outside, I think you got those wires mixed up with the wires going to the light. Easy to get mixed up because they are of the same shades of black and white.

"The knee bone connects to the thigh bone."

A continuous black wire path does not mandate having a single unspliced length of wire. You can have a continuous black wire path when the (black) wire coming through the wall from the inside junction box is connected directly to another black wire (may in turn be connected at its other end directly to yet another black wire) and the final end is connected to the receptacle. But you must be able to see all the ends of all the segments and verify they are indeed joined end to end. Same for the white wire path.
 

Last edited by AllanJ; 08-29-18 at 03:02 PM.
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Old 08-29-18, 04:01 PM
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Here is how the light is connected. Not sure it's relevant.
 
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Old 08-29-18, 04:54 PM
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Voltage need s.to be tested under load. Simply reading 120 volts does not mean everything is fine. A connection could be just touching enough to read voltage but fail under load.
 
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Old 08-31-18, 08:49 PM
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Allanj: "There is a moderate possibility that the light got wired into a series subcircuit with the receptacle which is incorrect and which would cause the symptoms you reported."


Yes. I traced the problem back to the next outlet before the junction box. That is a switched outlet -- something I didn't realize because I haven't been using that outlet. I was trying to tap into the switch loop for power to the new outside outlet/light. The voltage measured at 100V.

I've resolved the problem by tapping into a different power source.

This is a great website!! Want to thank everyone for the helpful comments. I guess I should know at my age that there's always a logical explanation, while 'coincidences' tend to lead astray.
 
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Old 09-01-18, 05:04 AM
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Project for a future date: Verify that the switched outlet (receptacle) you first tried to tap into does not have the same problem.

The switched receptacle had black and white power feed wires connected to its screws. To tap into it if you attached your new black and white wires to the other screws on the respective sides of the receptacle then you would measure the same voltages at the switched receptacle inside as you measured outside. Same idea as in your diagram above "Here's how the light" where the light wires are tapped into the outside outlet shown at the bottom of the diagram.

If two wires want to go under one screw, then cut a short length (pigtail), say 5 inches, and connect that to the screw. Connect the other end of the pigtail to the two wires in question. The exception is if the two wires do not touch each other and neither can slide sideways out from under the screw just before the screw is tightened.
 

Last edited by AllanJ; 09-01-18 at 06:19 AM.
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