Earlier today I was running my space heater in my bedroom at the full 1500 watts for about 2-3 hours. I turned it off and started to read so I could take a nap.
I kept hearing truck noises and other noises from outside so I thought I would enlist my regular fan to help get some white noise in the mix to sooth my mind a little. For the ADDer, having white noise can help sleep BTW.
Anyhow, I get up and go to the fan, and realize it’s not plugged in, so I go to plug it in and the outlet (a completely different outlet) was hot. I am not talking burning hot but it was pretty hot.
Curiously I went over to the outlet that the space heater was plugged in and it too was hot, but not as hot as the other one. I went to other outlets on the same circuit on the circuit breaker (two are even in a different room) and neither were hot, but they are on the same circuit.
So my question is two-fold. Why, when running a high wattage appliance does the actual outlet become hot and why would other outlets on the same circuit also become hot but others don’t?
Your help in me understanding this would be great. I was afraid that something scary was happening so I didn’t run the fan at all. I read and did my best to shut out the noise and ended up sleeping for 4 hours this afternoon!
It could be possible that the two hot outlets are wired incorrectly, or with too-thin wire. Or they may not be grounded properly. You should have an electrician check it out to be safe. There really is no good reason for an outlet to get noticeably hot.
The outlets are getting warm because they are offering resistance to the circuit, and current flowing through resistance creates heat. As you’ve already seen when you’re using a high current device, like your heater, the heat becomes noticeable. Now outlets are not supposed to be resistive, and it would be a good idea to find out why they’re being like that, especially if you plan to use your heater on that circuit frequently.
I have two possible reasons for you.
If the wiring is fairly new…
Many outlets have two ways they can be connected to a circuit. One is with attaching the wires to the screw terminals on the sides of it (the best way), and the other is to use the ‘quickie connectors’ on the back of them where you strip off a 1/2" of insulation from the wire and stick it in the hole. This method is Ok for alarm clocks and light bulbs, but it doesn’t make a great connection and is not so good for using heaters. I suspect that the outlet you had the heater plugged in to and the other outlet that is getting warm are connected in this fashion. The cure is simple, cut the wires off the quick connectors and attach them to the screw terminals. (obvious safety note: turn off the breaker before you do this)
If the wiring is older…
Time has tarnished the contacts in the outlet and/or the wire connecting to the outlet. The cure for this is to run down to your local hardware store and pick up a couple of replacements. When you do replace the outlets make sure cut off the old exposed part of the wire and strip the insulation to expose fresh, shiny wire. (same safety note as above applies)
KP235 is correct, i.e. there is resistance at those outlets.
Here’s what I would do pronto: Kill the circuit via the breaker panel and check out those outlets. In fact, if the outlets are fairly old, I would simply replace them with new ones (they’re very cheap). It’s easy enough to do; all you need is a screwdriver, wire cutters, and wire stripers. Make sure all connections are clean and tight.
Here’s something else you want to check out: Is the wiring copper or aluminum? If it’s aluminum, then that would explain the problem. (It’s difficult to make a good, tight electrical connection to aluminum.) If it’s copper, then what gage? 1500 watts will draw 12.5 A rms, which means you need at least 15 AWG copper wire.
I’d bet the receptacles are wired as KP235 said, with the push-in tabs. This creates a notoriously bad connection, and could get warm if a lot of current goes through it.
Although it’s pretty easy to change receptacles yourself, I always recommend getting an electrician to check it out, just to be safe, unless you’ve had some experience at this. Although unlikely, one mistake can leave you dead on the floor, or your house burned down (and it doesn’t have to be your mistake, it could be a previous electrician).
I haven’t seen 15 AWG copper wire before
IIRC, for a 12.5 amp load, the National Electric Code requires 12 gauge wire (12 amps is the cutoff for 14 gauge wire, since 15*80% = 12).
Don’t know about the dynamics of getting a tight connection with aluminum, but bi-metal corrosion is another factor. Simply put, when aluminum comes in contact with certain other metals (the screws or push contacts in this case), the two metals start to react and corrode. This corrosion increases the resistance of the connection and therefore the heat dissipated (see above posts). Generally, aluminum wire BAD, copper GOOD in house wiring. IIRC there was a gel you could apply to the contacts to stop this process. But if the corrosion is advanced, you would have to redo all the connections or better yet, rewire the residence with copper wire (Oh Joy !!)
Yep, there are all kinds of problems with using aluminum electrical wire for residential use; it’s difficult to make a good, tight connection, corrosion problems, increased wire resistance over copper (for same cross sectional area), etc.
If techchick68 has aluminum wire in her house, then I don’t know what to tell her. I once lived in an apartment in Cincinnati that was built using aluminum electrical wire. And the entire place was made of wood. Talk about a fire waiting to happen. I got the hell out there ASAP. (I don’t mean to scare anyone who happens to live in a place that was built using aluminum electrical wire. But if you do, I would get the entire system thoroughly inspected as soon as possible.)
There is another factor in wiring that should be mentioned. Sometimes, to save time, the electricians will use the socket as a connection point rather than pigtailing and running seperate wires to each socket on a circuit. This means that the little copper (or brass) bars that connect the two plug recepticles on each socket become part of the circuit, whether the that socket is used or not. This is sloppy, wasteful, and generally bad, and needs to be fixed. It is easy to spot, though. In general, if there are four wires, plus ground, going into a socket instead of two, and each plug recepicle isn’t controlled seperate, such as from a light switch for a table lamp, then it’s bad. If it has only two wires, then it’s probably OK. Also, plug recepticles do wear out in that they gradually become less and less tight, until they don’t contact the prongs of the plugs well, which creates additional resistance (small air gaps - arcing) and therefore heat.
Again, shut off the circuit before you check this.
I’m not sure I completely understand what you’re saying Engineer Don. I’ve always understood running wire point to point and using the outlets as a connection point is Ok, as long as you use the screw terminals on the sides of the outlet, NOT the quick connects on the back. This saves alot of wire over home running everything back to the breaker box.
I have to take exception with the warnings on aluminum wiring. Many places were constructed with aluminum prior to 1985.
Bi-metal corosion at outlets junctions and in the panel can be a problem, however there is no need to completely re-wire the entire place. All that is necessary is to pig-tail copper between the existing wire and outlets or switches using al/cu wire nuts filled with de-ox grease. (looks like elephant snot)
The house was built about late 1985 or early 1986. I don’t know what the building codes were back then… My father who owned a window manufacturing company was actually instrumental in getting building codes changed from the national average for egress and rooflite (sky light) requirements. It is possible that a local electric company was able to do the same type of thing. Meaning he was able to keep egress smaller than the national building codes and tempered glass in smaller rooflites instead of laminated glass.
I would assume that it’s copper wire. The house was built by a larger building company at the time and used larger electrical contractors…
I’ve been running that space heater on that circuit all winter and I noticed the outlet where I put the space heater on was always warm (as is the outlet on a different circuit in my office). But never noticed a secondary outlet…
Hmmmm, summer’s almost here so I will talk about it with my friend/landlord next fall but it still kind of baffles me since I don’t fully understand how electrical wiring works. I guess I will have to print this off and sit back and study it.
A.> If the Space heater was not facing the outlet it is pluged into, there would be a small amount of heat radiated from the back of the heater itself. Thus:
B.> Since the Heater was turned off:
It is possible that the heater was facing (and thus heating) the hot outlet and had gone unnoticed.
Had the heater been on, it would be more obvious where the heat had came from.
C.>Other prudent and logical reasons helping this theory:
1.)Why would outlets in another room not be hot?
2.)This is a long shot, but…
I am only assuming that since:
the room is probably relativly dark.
This would make seeing any sparks from arcing easy to see
I thought of the space heater itself causing the hot outlet too. It’s a good question. I also considered that, since it was a nap, it was daylight outside… could a focused beam of sun light have been hitting the faceplate - possibly filtering through the curtains/blinds, etc.? I think it may be overreacting to assume the the outlet was hot due to faulty wiring (though an ounce of caution is much better than having your house burn down).
Not necessarily. If the gap is very small, the arcing may not generate much light, plus it’s all behind a faceplate which may not be translucent enough to let the light escape.
I interpret Don’s words to apply to circuits where you may have a 20 amp circuit and 15 amp outlets on it. The wire comes into the outlet box and if you wire all the downstream outlets through the little tabs on the side of the outlet, you could be putting 20 amps through a little 15 amp piece of metal.
A better solution that doesn’t require you to run everything to the breaker box is to connect the wires together and then connect them to the socket - either with some kind of connector or twisting the wires tightly together and clamping them BOTH under the same screw of the outlet.
Just had to do this in my house where the dyslexic electrician wired 80% of the outlets backwards AND used crimped connectors that were failing (some outlets had no ground, visible arc marks on some connectors…) Worse, there was no slack in the wiring so I had to re-use the existing stripped wire in some cases - had to clean up the surface with a knife. I would have loved to cut off the old wire and use freshly stripped wire, but it wasn’t going to happen.
Everybody has been kinda tip-toeing around the solution, but I haven’t seen anyone hit the nail squarely on the head yet.
The only reason that an unused outlet would be hot is that it is serving as a high-resistance connection to the outlet that is in use. I’d be willing to bet that the feed wire from the breaker box in techchick68’s house goes first to a junction box buried in a wall or ceiling somewhere, and from there, branches to the various outlets. Most likely, the two she’s talking about are wired in series on a branch feed from that junction box, while the others are on other branch feeds. Passing the current necessary to power the heater through the high-resistance point – the second outlet – is generating the heat.
techchick68, the problem is not at the outlet that served the heater, but at the outlet that was hotter, the one you plugged the fan into. Either the connections were poorly made, or, as Engineer Don suggests, the connections were accomplished via the “quickie” shove-in connections on the back of most newer outlets.
Another relevant question: What do you usually do when a fuse burns out? Many folks[sup]*[/sup] will go out and buy a higher-rated fuse, or even short out the fuse entirely (!) by putting a penny in the socket, or the equivalent. This is one of the stupidest things you can do with your home wiring. If you’re having a problem with fuses blowing, there’s two safe solutions: You can reduce the load on that circuit, or you can have the entire circuit (not just the fuse) re-wired to handle the load. If you just put in a bigger fuse and continue to load a circuit above what it’s intended for, the wiring will (you guessed it) heat up.
[sub]*Note: I’m not saying that teckchick is one of these folks… I think she probably knows better than that. I’m just mentioning because others might not know better, and this is Very Important, safety-wise.[/sub]
