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Original scenario (see edit below)

As with many people, I have been working from home since last year. Last fall, I moved my workspace into my basement. The area I'm working in is serviced by a chain of 3 basic outlets, all 15A/125V, coming off a 15A breaker. Here was the setup before things went wrong:

  1. ⚡ - 15A breaker
  2. 🔌 - 15A/125V outlet
  3. 🔌 - 15A/125V outlet
    • ♨ - space heater
  4. 🔌 - 15A/125V outlet
    • 💻 - surge protected workstation of various equipment
    • ❄ - mini-fridge

This configuration has been working fine for months.

Yesterday, I plugged my tablet charger into the surge protector (like I had been doing occasionally for the past few months). I heard a light pop and noted my workstation no longer had power.

The space heater was still running, so I knew the breaker hadn't tripped. I toggled the surge protector switch to no effect. I then unplugged the surge protector and tried connecting a simple phone charger, but still had no power. I reset the breaker for good measure, but nothing changed.

A few searches later, I learned that outlets CAN overload and die, so I moved on to replacing the outlet. (I also moved the mini-fridge onto a different breaker's chain.)

After replacing the outlet and wiring it just like it was before (grounded also to the box, white wire on top silver screw, black wire on top gold screw), I plugged in the same simple phone charger, and was relived to see power. I reassembled my workstation, attaching only the essentials (less equipment than previously attached) to the power strip. Again, everything came back online. Satisfied, I turned off everything (including the space heater) and called it a night.

This morning, I went to my workstation and started turning things on for work, including the space heater. Everything seemed fine--everything was running, and I heard no pops or zaps. I walked away to get some breakfast, but when I returned there was a distinct smell of burning plastic. The space heater was still running, but my workstation once again had no power.

For now, the whole chain is shut off at the breaker.

So, before I call in an electrician, is there anything I might be missing? I haven't inspected outlet #2 yet, but I'm guessing it's okay based on the working history of the configuration, and that the space heater never stopped working (I'm new to all of this, so of course I could be very wrong).

Here's the run-down again:

  1. 3-outlet chain (15A/125V)
    • Nothing on #1
    • space heater on #2
    • WFH workstation on #3 via surge protector
    • mini-fridge on #3 (removed after first outlet blown)
  2. Re-attach a charger to the surge protector on #3
  3. Outlet #3 stops providing power
    • breaker NOT thrown
    • space heater still running
  4. After troubleshooting, replace the outlet
  5. Outlet #3 seems to be fixed
    • WFH workstation receiving power
    • space heater still running
  6. Next morning, turn on workstation and space heater (everything seems fine)
  7. Walk away and return to smell of burning plastic
  8. Outlet #3 again not providing power
    • breaker NOT throw
    • space heater still running

Extra info from the comments:

  • The replaced outlet was not back-stabbed
    • Assuming the same for the rest, but will check
  • No rust or moisture seen in/on the replaced outlet/box
    • Will inspect other outlets for similar concerns and update the question
  • I'm planning to inspect the entire circuit and test for faults (need to buy a meter first...)
  • Panel and breaker are both GE

Edit:

I've made a fairly important edit to the info above based on new information from working on it today. The biggest change is that I found I actually have THREE receptacles on the circuit, not four. This likely affects some of the answers below, so watch for edits there, too.

After today's work:

Receptacle #3 The replacement receptacle actually didn't blow out! It's just that the white/neutral line apparently broke while I was hooking it around the screw, because a piece of wire fell off as I was removing it again. I'm surprised it didn't cause a short (and trip the breaker), but it may have been arcing, and I just caught it in time before it did too much damage. I replaced the receptacle with a nicer one anyway, stripped some more white wire and made sure the connection was good and tight. Power is still flowing a few hours later, although the only thing on the circuit at the moment is my workstation on #3.

Receptacle #2 The former home of the space heater had loose screws. I'm really surprised there wasn't a bigger problem there, but everything looked to be in good order (no signs of arcs or burns), so I simply tightened everything and moved on.

Receptacle #1 This one surprised me. This one has been empty for a while, but when I pulled it from the wall, the black/hot wire and its terminal were charred and partially melted! Burned receptacle Now, a few years ago, I had a dehumidifier attached here. The dehumidifier suddenly stopped working, and I figured it had expired because it was old and second-hand. A new dehumidifier went on a different circuit, and the receptacle remained empty for a long time, so I never bothered to check it out. Needless to say, I replace this one, too.

(What happened to the original #1?)

It was also empty, so I just assumed it was on the same chain as the others in that area, even though it was on a different wall. I'm glad I checked for current before I started pulling it though, because I only had the other chain's breaker turned off. Boy was I confused when the tester told me it was live... But anyway, still empty, so it was an irrelevant piece of the puzzle. Sorry!

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  • Burning plastic, sounds like you could have some arcing going on. You may wish to invest in an AFCI breaker or GFCI/AFCI combo breaker since you're in the basement. – MonkeyZeus Apr 19 at 16:11
  • If you have moisture in your walls rusting out your outlets then you might need to invest in weather-rated outlets. If you have rodents chewing the wire inside your walls then you'll need to replace those wires and deal with the rodent problem of course.. – MonkeyZeus Apr 19 at 16:14
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    Sounds good. Do note that AFCI will help to avoid a blown outlet but you shouldn't rely on it as a permanent solution; ie you shouldn't plan to reset the AFCI breaker daily. If an AFCI trips then your goal should be to address the root cause. The connection which is actually arcing should be properly addressed. For this you will likely need to call a professional. – MonkeyZeus Apr 19 at 16:37
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    By the way, very nice observation skills and thank you for being detailed and coherent. Far too many times an electrical question is "Something happened, how do I fix it?" and then the comments have to "pull teeth" by asking "Okay, what happened?" – MonkeyZeus Apr 19 at 16:43
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    @JACK The outlet I replaced was not--it used the side-screws, and I replaced it using the side-screws. I can't yet say whether the others in the chain are the same way, but when the basement was finished (previous owner), I assume they were all installed at the same time by the same person. (And we all know assumptions are worth their weight in your hand.) – TheJim01 Apr 19 at 16:48
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You have an overloaded circuit it may have been fine in the past but the space heater alone is a full load for a 15 amp circuit , add the fridge and when the 2 cycle at the same time the circuit is overloaded even further.

Add the watts for each device like 1500 for the space heater. From 350-700 for the mini fridge already at 100% of a 15 amp circuit capacity further adding the work station there is a serious overload condition especially during startup on the fridge compressor.

On 15 amp circuits failures I have been called in for are almost always the backstabbed or push in connections to the receptacles. You may have fixed 1 but if stabs were used it could fail again at the same point or another point in the chain of receptacles and or lights that could also be on that circuit.

15 amps x 120v = 1800 watts the breaker probably won’t trip until 2000+ remember the start up of the fridge it will be 3-5x the wattage on startup.

Your breakers are inverse time a dead short they trip immediately but a overload is different a compact breaker will hold 3-5x it’s rated value for ~10 seconds if the overload is only 16 amps it may hold for an hour until it trips depending on the brand and age.

So it is best to reduce the load on the circuit, yes it may have held in the past but overloading a circuit is a good way to have a fire.

There are some obsolete breaker panels out there that have a 60% failure rate and the rate increases with continued cycling. We don’t know if you have a federal pacific stablock panel or Zinsco that are known to have problems especially after repeated overloading.

When load calculations are done electricians are allowed to use 100% for non continuous loads and 80% for continuous. A continuous load is 3 hours or longer is continuous. Motor and lighting loads are always rated as continuous so that mini fridge at 3-6 amps is really rated at 3.75a / 7.5 amps so I hope you can see the overload is the problem and the burned plastic smell may be a overheated backstab connection (even a bad wire nut / screw connection can get hot) when overloaded.

Edit added because fridge was moved; The damage may have happened prior to moving the heater. I will turn the circuit on and use a lamp and check at each receptacle working back to the service panel. The failure is 99% in the last dead one you check or possibly the first live one working from the dead side. It is very rare for the problem to be in the panel but it could be and in all cases with the info we have so far it could be the white or black wire that the connection has failed.

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  • The breaker box and breaker are both GE. You are right that there was definitely too much on the circuit, but I'm unclear on why it took until now to come to light, and why it suddenly happened twice over two days. Was it simply bad luck/timing that the header and fridge were trying to cycle at the same time? But then it happened faster after I removed the fridge from the equation. I suppose the heater could have gone bad and started pulling more power, but I'm skeptical, due to my lack of knowledge and experience in this realm. – TheJim01 Apr 19 at 17:20
  • OK, so you're saying the problem might be the wiring in outlet #3. If the heater damaged the outlet, then that damage may have continued on to #4. Is that a reasonable way of putting it? – TheJim01 Apr 19 at 17:25
  • It could be a receptacle prior to 3, possibly 3 even if nothing was connected to 3 itself other than the feed to #4. GE is a good brand I do not remember having anything other than a failure here and there and that happens with all brands. If a breaker has not been cycled for a decade it may actually cycle easier after the first trip or cycle. – Ed Beal Apr 19 at 18:03
  • Thanks, I appreciate your time and advice. My current plan is to inspect all the receptacles in the chain, ensure tight connections, and get a meter to verify proper voltage. If anything looks burnt or like there has been arcing, it's getting replaced. I've been wanting to put in an electric fireplace to replace the space heater... My thought now is to give it its own breaker. :) I'll update my question if I find anything out of the ordinary. – TheJim01 Apr 19 at 18:17
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    Space heaters regularly cause these issues. A fixed electric space heater “built in” has to comply and usually requires a dedicated circuit. – Ed Beal Apr 19 at 18:25
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It's receptacle 2

The way these things fail is either with an open connection (i.e. the connection burning out), or ongoing arcing at that connection. Arcing is itself a load, and it makes a lot of heat.

So the next step here is to inspect receptacle 2. Pull wires out of any backstabs, and inspect closely for evidence of arcing on both hot and neutral. And make sure connections are torqued down properly: avoiding the above is why NEC was changed to require torque screwdrivers.

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  • Hi, thanks for your answer. I updated my question based on work I did on the circuit today. If you'd like to updated your answer based on the new info, great! I appreciate your time and assistance. – TheJim01 Apr 25 at 3:19
  • Sorry @TheJim01 I meant all along to say it was the receptacle before the one causing you trouble, and I thought there were 4. So I was meaning to say #2 all along It sounds like it was exactly that - the last guy was a limp wrist and didn't torque anything. This is why NEC now requires torque screwdrivers be used. – Harper - Reinstate Monica Apr 25 at 6:10
  • Making another dumb statement like a “builders grade receptacle are only designed to last until closing” is well deserving of a down vote. Builders grade when properly installed and not overloaded easily last 20 years. – Ed Beal Apr 25 at 14:48
  • @Ed okay then, removed. – Harper - Reinstate Monica Apr 25 at 18:24

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