Loss of power in a 20-Amp kitchen circuit

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Old 03-26-15, 08:53 AM
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Loss of power in a 20-Amp kitchen circuit

A 20-Amp circuit has stopped working. This circuit powers three kitchen wall outlets plus an over-stove vent light and fan. (If there are other things on the circuit, I cannot find them.)

Over the past two years I've replaced a 1000W microwave with a 1250W microwave and more recently replaced a 1000W toaster oven with a new 1500W toaster oven to this circuit. Both are plugged into the same outlet and both have been working fine, though I see now (by virtue of posts I've read on this forum) this is probably too great a load on this circuit. What I don't understand is why this never tripped a circuit breaker. Is it possible this kind of load and use would degrade the circuit over time rather then just tripping the circuit breaker if and when overloaded?

I've replaced all three outlets and tested the circuit breaker (by switching it with a known, good breaker,) all to no avail. I simply cannot find what is causing the loss of power.

I'll be getting voltage testing equipment later today, but in the meantime I'm now inclined to believe the problem may lie somewhere within the light/fan mechanism in the over-stove vent hood.

What I don't understand is, if there is a problem within the light/fan, why is one outlet, which is at the end of the circuit, at least partially functional while no other outlets are? (When I say partially functional: this outlet currently powers a small, $10.00 fluorescent light stick which is mounted nearby over the sink. As mentioned, it plugs into the last outlet on the circuit. If I plug in and turn on (say) a toaster in the same outlet, the light will go out remain and out for several hours. It does finally come back on but I have no control whatsoever of when it will come back on. It seems to have a mind of its own. Can I ask what might be happening to the current and voltage on this circuit to cause this kind of sporadic activity?
 
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Old 03-26-15, 09:04 AM
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plus an over-stove vent light and fan. (If there are other things on the circuit, I cannot find them.)
A violation of current code.
I'll be getting voltage testing equipment later today,
Be sure it is an analog multimeter ($8-$15) not a digital multimeter or a non contact tester.
1250W microwave and more recently replaced a 1000W toaster oven with a new 1500W toaster oven to this circuit. Both are plugged into the same outlet
If used at the same time exceeds the amp rating of the circuit.
I've replaced all three outlets and tested the circuit breaker (by switching it with a known, good breaker,) all to no avail. I simply cannot find what is causing the loss of power.
IF everything is on the same circuit that is your problem. You need at least two dedicated 20 amp circuits for receptacles only. The fan is not your problem it draws only a couple of amps but by code it and any lights can not be on the two 20 amp receptacle circuits.
 
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Old 03-26-15, 09:07 AM
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It sounds like the high loads have loosened a connection.
 
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Old 03-26-15, 09:18 AM
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Are you sure that the "last" receptacle is really the last in line?

Are both halves of each duplex receptacle dead?

"the kitchen counters need two exclusive 20 amp circuits."

The kitchen counter circuit connected to the fan might be grandfathered. Fixing the loose connection and/or replacing defective receptacles won't terminate the grandfathering and force you to upgrade the entire circuit, but you may not add more wiring or branches.

If you pressed a receptacle with your thumb (not too hard) as if it were a pushbutton, does the circuit come to life? That might find a loose connection for you. Sometimes the wiring daisy chains through the outlet box using both screws or both holes on the same side of the receptacle unit. There is a little tab between the two screws that under some circumstances is supposed to be bent back and forth until it snaps off but sometimes fractures by itself when it is supposed to still be in place.

We suggest that you do not use the holes in back of a receptacle for making connections unless there is a special screw on the side that clamps the wire tightly in the hole without the ability to twist or rotate. Test using a scrap piece of wire or a pigtail (scrap piece of wire ultimately used as a jumper with both ends in the same box).
 
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Old 03-26-15, 10:45 AM
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Thank you, Ray,

Because I'm new here, I do not yet have HTML abilities and thus am unable add your individual quotes.

The house was built in the early 80s before there were such things microwaves. This is the original wiring in the house which I can see, based on what I've read on these forums, that it is out of code. The question is now, what to do about it. I can understand the need to add an additional 20-Amp circuit. And I also understand that no lights should be included in this circuit. But I am curious to know why that is so? What happens (or can happen) to a 20-Amp kitchen circuit when a light is included in the series?

Thank you for your tip about an analog voltage meter. I'll make sure that's what I get.

At the moment I'd just like to restore power to the outlets in the kitchen. (The microwave and toaster oven are unplugged and will remain so.) I was also looking to understand why the last outlet in the circuit worked, though sporadically, while the others did not.

Thank you for taking the time to respond.
 
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Old 03-26-15, 10:55 AM
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Thank you, Allan,

I'm pretty sure it's the last outlet in the circuit, as there were only two wires (hot and neutral) connected to the outlet.

The original outlets were, indeed, back-stabbed. When I replaced them, I made sure to connect at the screw terminals on the side. I was also careful to match the location of all the wiring. (i.e. the top wires on the old outlet were placed on the top of the new outlet. Black wires were connected to the hot terminals. White wire was connected to the neutral terminals.)

I would assume the fan/light included in this circuit is grandfathered. This is the original wiring in a house built in 1982. Codes probably allowed it at that time but have since changed and no longer allow them.
 
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Old 03-26-15, 07:54 PM
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I also understand that no lights should be included in this circuit. But I am curious to know why that is so? What happens (or can happen) to a 20-Amp kitchen circuit when a light is included in the series?
The lights just add unnecessary load to the circuit. You are right that when your house was built there was no requirement for two small appliance branch circuits and it was not a code violation for the vent fan, light and even possibly a disposer to be on this circuit, but today you have high current drawing appliances that need every bit of capacity you have and then some. You probably have a bad connection somewhere in this circuit that has gotten worse because of the excessive load. Pull all the receptacles on the circuit and try replacing all the wire nuts you find and test as you go with your new meter.
 
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Old 03-30-15, 08:27 AM
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I don't know if anyone is still around who might be willing or able to provide more assistance. I've purchased both an analog and digital multimeter and taken readings on a kitchen circuit that has ceased to function. I'm trying to find where the source of the problem might be.

To summarize: I have a 20-Amp circuit feeding three kitchen outlets plus an over-stove vent fan and light. (I understand lights on a 20-Amp kitchen circuit are now out of code, though it wasn't in 1982 when the house was built.) The first two outlets and the vent fan/light have ceased to function. The third and last outlet on the circuit provides enough current to power an inexpensive fluorescent light stick, but any additional load plugged into the outlet causes a loss of power for several hours until, for reasons I do not yet understand, it becomes functional enough to again power the light stick. All outlets have been replaced with special care taken to ensure they are wired correctly. If it makes any difference, this circuit is located on the rear wall of the house and is closest to the electric panel on the external side of the same wall.

Using an analog multimeter, when I test hot to neutral in the first two outlets, I receive only a very small reading, where I should read 120V. Testing hot to ground does read 120V. Ground to ground and ground to neutral are both zero volts. Testing hot to ground in the top slots of the third outlet reads 120V. A test of the lower slots in that outlet reads voltage only in the high 90s. (I do not know what that may tell me, if it tells me anything at all.)

I've disconnected and removed the stove vent hood and tested the main power lines that fed the fan and light. They test the same as the outlets. i.e. hot to neutral produces zero volts. hot to ground produces 120V. neutral to ground produces zero volts.

Since there is only one line coming through the wall to feed the vent fan/light, I believe this tells me there must be a junction box somewhere inside the wall. Can any of you verify my thinking is correct? Or is there some other configuration I may not have considered.

My next step is to remove a cabinet that sits over top the range hood in order to access the wall, where I intend to break into the sheet rock and try to locate this junction box.

As you can see, I've still not found the cause of the problem. As I slowly work my way through the circuit, I now believe one of the wires in the junction box must have loosened enough to cause this loss of power. But, honestly, I do not know. And so, I ask for your help in analyzing the information I've provided. If there is a junction box and I am able to locate it, what can I expect to find? I do not yet understand how the third and last outlet on the circuit can be functional, while no others are. Does this provide any additional and important information? Or, is it just not important to the problem at all?

Thank you in advance for any help and guidance you are willing to provide.
 
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Old 03-30-15, 09:15 AM
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There is almost certainly a loose or broken neutral somewhere in this circuit. Unfortunately it looks like you tried the obvious connections by replacing the receptacles. Were there any wirenut or crimp connections in any of those boxes? If so, remaking those could help find the problem.

There could be a hidden box somewhere in the wall, basement or attic. Maybe the circuit is spliced in a light box or switch box somewhere. The wire itself could be broken, for example from a nail or screw puncturing it, a box clamp that was too tight that finally broke through, or something like rodent damage. I suppose the problem could also be at the breaker box, either the breaker going bad, connect to the bus corroded or loose neutral on the bus bar but this option doesn't really fit the diagnostics all that well.

To further diagnose, you could disconnect all of the devices on the circuit and test resistance on all of the wire segments to try to find a bad one. Alternatively at some point the labor diagnose the problem exceeds that of just abandoning the old wiring and pulling new.
 
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Old 03-30-15, 09:21 AM
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when I test hot to neutral in the first two outlets, I receive only a very small reading, where I should read 120V. Testing hot to ground does read
Then you have a poor neutral connection. That explains the fluorescent working. The neutral opens under heavy load.
I do not yet understand how the third and last outlet on the circuit can be functional, while no others are.
Appearances could be fooling you. It may not actually be wired that way. Mystery boxes can be hard to find. My solution on this would be to abandon in place the wiring that doesn't work and run new.

Is there a junction box where the fan connects are just a cable coming out of the wall? If just a cable finding where that cable comes from may be part of the solution it could lead to a mystery or just a connection in the wall with no box.
 
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Old 03-30-15, 09:45 AM
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It does not make sense that devices first in the string do not work while things downstream do. Your reading are indicative a loose neutral. I would start at the panel.

Splices should not be buried for this exact reason.
 
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Old 03-30-15, 02:41 PM
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Thank you again, Ray.

Based on my new and growing knowledge of home electricity, that there is a problem in a neutral connection makes sense to me.

The line feeding the vent fan/light comes out of the wall. There is no junction box that I can see, but it would seem there has to be one inside the wall somewhere. Finding it is the next logical step for me.

As much as I wish I could simply re-wire anew, the declining health of both of us over the past three years has depleted too much of our savings. I'm relegated to finding a way to repair this myself and am very appreciative of the help you and others are providing.
 
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Old 03-30-15, 02:44 PM
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Thank you, pcboss.

I wonder if you (or anyone) would be kind enough to elaborate and explain in a bit more detail where I should start in the panel? If this is a loose neutral, would you recommend that I disconnect each of the white wires in the bus panel (outlined in red) and reconnect just to reestablish a good connection on each? Or, is there some other step(s) you recommend? (The breaker controlling this circuit is outlined in yellow.)

Working in the panel scares me, especially since it has no specific shut-off. I'm assuming if I shut off all of the 240 breakers, that will effectively shut off the power to the panel so I may work in it. Can you verify this for me?

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Old 03-30-15, 03:14 PM
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The white wires you can just verify that the screws are snugged up. You do not need to disconnect and reconnect them. At the breaker you would want to make sure the screw is snugged up and the wire is seated under the screw. Also, remove the breaker from the bus bar and visually inspect to see there is no corrosion or burn marks.

You have a split-bus panel, which effectively means the upper six double-pole breakers are together considered the "main" If you turn off the bottom right of that group of six, it turns off power to the lower section of the panel. The bus bars under the upper breakers and the main lugs at the top are always live.

The fact that a red wire goes to the kitchen circuit makes me think this might be a multiwire branch circuit, which throws a wrench into the mix. Is the wire in the first box in the kitchen red? Do you have both red and black wires in the kitchen boxes?
 
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Old 03-30-15, 03:40 PM
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I'm sorry, ibpooks. I missed your response until just this moment. Thank you for taking the time to respond.

There were no wires that were crimped in any of the boxes. The original outlets were back stabbed, but I connected all of them to the side screws when I replaced them.

During the week as things unfolded, I considered that the cause may have been due to some sort of rodent activity, particularly in our attic. We have occasionally had mice and even rats enter the attic and it wasn't beyond reality that something had chewed or otherwise damaged electric lines up there. IF, when the house was built, the electrician placed a junction box that fed this circuit in the attic, it lies in the far reaches of the attic where there is no flooring and is particularly hard to get to. Since this circuit is so close to the breaker panel, I just assumed the electrician didn't run the line all the way up to the attic and back down to the outlets, but placed a junction box somewhere on a stud somewhere behind the kitchen wall. I don't know that for a fact, of course, and I may cut and place some flooring up there just so I can see if there is a junction box there. But for the moment, I'm looking to tear into some of the sheet rock behind the range hood and a cabinet that sits above it. (I'm having a problem at the moment removing that cabinet. I can't seem to budge the two screws that hold it in.)

At this moment I don't know how to test for continuity. Just like I learned to read voltage with a multimeter, however, I'm sure I can learn how to test continuity. But even if I found the wire with the least or the most resistance, it seems I'd still be saddled with the problem of finding where it was located.

Before I purchased test equipment, I "tested" the breaker by switching it with one of the other 20-Amp breakers in the panel. The breaker served another circuit fine, and the breaker placed in the slot of the original breaker exhibited the same problems on the kitchen circuit, all of which led me to believe there's nothing wrong with the breaker.

Thanks again for taking the time to reply.
 
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Old 03-30-15, 03:51 PM
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Thanks again, ibpooks,

As I replaced the outlets, I don't recall any red wires but I remember some of them seemed to be faded. I thought they were both black and white, but I'm going to take another look and will respond later this evening.

I don't know what a multiwire branch means, but I'm also going to research it too.
 
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Old 03-30-15, 04:00 PM
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I don't know what a multiwire branch means, but I'm also going to research it too
Your house is supplied with 240 volts not 120 volts as many think. The 120 volts is derived from the neutral and one leg of the 240 volts. A multiwire circuit consists of both legs of the 240 volts, black and red, and a white neutral. Some receptacles on a multiwire circuit use red and white and some use black and white. This gives you as much 120v power as two cables with two wires each but uses only one cable with just three wires.
 
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Old 03-30-15, 04:12 PM
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ibpooks...

Here is a photo of the first two (of three) outlets on the circuit. As you can see, the color of the lines are black and white, though the black does appear to be faded.

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Old 03-31-15, 08:48 AM
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Ok, so we now know there is a missing junction box somewhere. The wire that leaves the breaker is red and the wires at the receptacles are all black. The trick is finding it.

A few tips. If the house was done by an electrician/builder and at some point passed a construction inspection, there will not be a box behind the wallboard. That has never been allowed. If there has been a handyman-special kitchen remodel at some point in the past then you probably should be concerned about a buried box. A junction box in the basement, crawlspace or attic is legal, so that is a real possibility. If there are any other lights or switches on this circuit the splice could be in either of those boxes. Sometimes in older homes the kitchen circuit also fed the garage outlet, outside outlet, basement outlet or sometimes even the bathroom, more possibilities.

There are wire tracer devices that could help, but I'm not sure where you could borrow one. Maybe check around at tool rental places? I haven't priced in a while so I couldn't say if it's practical to buy one. You basically hook up a transmitter device to the wire at the breaker and try to track it with a wand you sweep along the walls. One brand is called a fox and hound.
 
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Old 03-31-15, 11:08 AM
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Thank you, Ray. As I'm reading and learning about multiwire branch circuits, it seems two breakers (120V) are usually combined to form 240V. Often, their respective on-off switches are also joined in some way. If that's the case, I can't seem to determine what other breaker in my breaker panel might be operating in concert with (or associated with) the breaker that feeds the circuit in question.

Am I getting this right? If the circuit is comprised of two 120Vs, shouldn't there be a second 120V in the panel that I could recognize and identify?
 
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Old 03-31-15, 11:18 AM
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Thank you, ibpooks. This information is very helpful.

I have no basement. The circuit I'm dealing with is on the inside, rear wall of the home. The breaker panel sits on the externally on the SAME WALL. Knowing that it was forbidden to bury a junction box inside the common wall gives me new and important insight in finding where these lines are all connected. It tells me they may, in fact, be located up in the attic. (Considering the length of time we've lived in this house, I can't imagine any one did and kitchen revisions before we moved in. The lines I'm dealing with must be those installed when the house was constructed.)

If there's a junction box up in the attic, it's located in the far reaches of the attic, which is a place that has no flooring whatsoever and will be very difficult to reach. I think my next step, then, will be to buy and cut some plywood flooring to place up there so I can better maneuver around as I search for the junction. Does that make sense to you?
 
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Old 03-31-15, 02:57 PM
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I'd probably try a wire tracer next.
 
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Old 03-31-15, 05:30 PM
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it seems two breakers (120V) are usually combined to form 240V.
Strictly speaking they are two single pole breakers one on each leg of the 240. In fact you can also use a two pole (240 breaker. The important thing is they must be on opposite pole of the 240. If they aren't you can cause a dangerous overload on the neutral.

The circuit I'm dealing with is on the inside, rear wall of the home. The breaker panel sits on the externally on the SAME WALL
You could abandon the old cable and run new cable in conduit from the panel to the nearest entry point to the bottom cabinets and through the cabinets to each point you have a receptacle. At that point in the cabinet you would run cable in the stud space up to the receptacle. A bit of a gray area but you can probably run the cable unprotected (no conduit) through the cabinets.
 

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