Oil-filled heater cord gets hot (2025 Update)

Where along the cord does it heat up. I ask because a bad connection at the plug end will cause the cord to heat at that end. If the cord heats along the entire length, then the cord is too small and should be replace (or the appliance has changed as is using a lot more current). If the cord heats at the plug end, the plug may not be bad, the outlet it is plugged into maybe worn and need replacement. There is no reason to remove a grounded plug as long as it is properly wired to the two strand cord (i.e., the ground should not have any wire attached to it).

While it is not unusual for a cord to get warm, it should not get hot. If it is the cord getting hot, then the cord, not just the plug needs to be replaced. If it is the original cord and if the cord was properly sized to begin with and if it is not damaged, then you should be fine.

However did you notice all those "if"s. Maybe it is time for a new heater. It is not always easy or safe to replace a cord, unless you know what you are doing. Maybe you could get your building maintenance to fix this one as well.

try to measure the power used by the heater, see if the heater is somehow going bad and drawing too much (although I can't imagine how exactly a heater might start drawing more power)

if the heater is still good you need to replace the cord with a wire capable of withstanding the current draw of the heater.

Appliance cords are governed by U.L, not the NEC. As such, It's quite common to see undersized appliance cords. 18 amp air conditioners with a #14awg cord. 16 amp hairdryers witha #16 awg cord. Likewise, it's also not uncommon to see percolators, toasters, portable heaters and the like with cords 1 or 2 awg sizes smaller than the appliance calls for under NEC rules.

Thanks (as well to other posters), that points to my plug replacement as the problem. I understand that space heaters have special "heater cord" as opposed to the old trick of taking a standard 3' extension cord and cutting off the end. Is there a special "heater plug" I should get? Or is this just too risky? I've replaced plugs on lamps, vacuums, etc. without this type of problem. Can you get "heater cord" with a prefab plug (i.e. @ Ace, Borg?

OK, good to know.

Fundamental fact is that plug-in electrical space heaters are dangerous. One place where I worked, the town fire marshall would not permit them, period.

The danger is that they develop hot-spots in their wiring under sustained use, like at plug contacts. Metal oxidizes, contact becomes more resistive, and temps continue upwards. Sometime when nobody's looking, smoke becomes visible, then flames.

You really want to use properly oversized wiring, and screwed-down, large-contact-area connections. Or not use them.

That’s crazy. Seems unlawful and priming themselves for a law suit. How can you shop for better appliances?

What do you mean, OP, by a modular electric plug by ACE? I only know of modular telephone plugs. If you are using anything with prongs that stab into the wire, or any form of quik-connect, stop that. The only thing you should be using for a heater have screws where you strip the wire by hand, wrap the wire around the screws, and then screw them down firmly, so that you make a good connection. I can't emphasize this enough. Especially since you say even the new plug heats up.

I have some first hand experience with this. I have had this heater for at least 46 years and it was 20 or 30 years old when I got it, for free somewhere I'm sure. All metal case, sheet metal, probably from the 50's but maybe the 40's. It has an adjustable thermostat. (My name and phone number is on it, meaning I lent it out, but so many years ago I don't remember.)

Back around 1980 I had a landlord in Brooklyn who frequently didn't provide enough heat, to save money, so I used the heater. It was a small room, 6' wide by about 12' long, intended for the maid in this 6 or 7 room apartment, built as a luxury building in 1930. (Doorman, elevator operator, switchboard operator, mail delivered by staff to the apartment, and in every apartment: hardwood floors, parquet floor in dining room, cedar closet, large dumbwaiter down the basement where the concierge took deliveries like groceries etc. rang the dumbwaiter doorbell, and sent them up to the kitchen, and basement facilities for laundry, that is, sinks but including gas sheet dryers 6-feet high, 5" wide, that pulled out like drawers with a rod at the top to hang the wet sheet. My apartment had been leased to the VP of Standard Brands, and the apartment above me had been leased by Allen B. DuMont, of the Dumont TV network and TV company.

dryers were there but everyone else was gone by the time I moved in in 1973.)

Two apartments on each of the top 5 floors were large with maids' rooms. The same apartments on the first floor were not as large because the entrance hall and lobby took up a lot of room, and they had a second entrance straight to the lawn and the street and were intended to be doctor's offices or similar.

I woke up for some reason and could see the receptacle without rising from my bed, and the flame was 1 or 2 inches high. I would not normally tell something so personal but it adds a lot to the story.... As I reached for the cord to pull the plug from the wall, the girl I was with kept grabbing my elbow and pulling my arm back. I can't imagine why. I'm sure she didn't want the flame to continue. I didn't panic but maybe she had. On my 3rd or 4th try I was stronger than she was and I pulled out the cord, and the flame died almost immediately. Nothing but the plug was damaged, and even it would have continued to work if it were not a heater. I thought it was partly carbonized. It was light out when I'd awoken. I wonder how long it had been burning.

Most of this doesn't apply to you, I think. The receptacle was from

1930 and probably was used a lot, and maybe receptacle quality has gone up since then. It was clearly not very tight when I put the plug in and took it out. That was the weak link. The plug was hard rubber, and flammable. I replaced the plug with a modern one, at the time, but I don't think the style is sold anymore. It's rectangular so that 3 things can be plugged in side-by-side, and it's hard or impossible to get plugs like that now. The ones that come preattached on cords have flanges** at the wall to make them wider, even when they carry barely any current.

No, ebay has a few, not the one in the middle:

Vintage Electric Supply: of these is better than what modular sounds like to me, but you can also use one from Ace. I assume your heater is no more than 15amps?

**For example, look at the flange on the red plug. I hadn't used this heater for 40 years, but this was the coldest winter Baltimore has had in the 41 years I've been here, with temps down to 6^F at night, and I dug out the heater from under the bathroom sink. (BTW, I still have the heater my mother bought in 1947 when I was newborn so that she could warm the bathroom for my bath. (In those days even in a middle-income home, they were the size of a small bedroom, because originallly, bathrooms had been convertedbedrooms and they had not yet noticed that they could make them smaller.) It was in perfect condition, even the cloth cord, until 10 years ago a cardboard container of toilet bowl cleaner under the sink sent out vapors that damaged the chrome grill. It still works fine, and has a foot switch but it's bigger than the older one, and it has no thermostat, because of its intended use.)

At first I couldn't remember the details of the older one's history, and I would only use it when I was awake and watching, but after 10 hours of use, seeing it turn on and off many times, and feeling the cord and the plug occasionally, I used it all night. I still won't leave it plugged in when I'm out, though after about 10 days of use, I probably couldt. I still have a furnace that works but I guess this room was losing heat through the window. The rest of the winter won't be so cold.

The cord is still supple (maybe I replaced the cord?). I can't see how much copper is inside, and the cord gets slightly warm as well as where it's plugged in but never hot, never at all unpleasant to touch,

I think Paul from Brooklyn knows all this, and the previous post too, but just for old time sakes.

....

He had been cited by the housing department several times. Including for turning down the heat during the middle of the day, even though that is illegal and we had several old ladies living in the building how were home all day. Miss Tieke upstairs, Miss Hussey and Miss VanDyne (one was a nurse for the other but I could never tell which). Mrs. Rutledge. The landlord when I moved in was fine, but she was old, a widow, and she sold the bulding and moved to Florida.

The new one claimed to be a plumber but he wasn't good at it. He had a couple other buildings he was treating as a slum. And one person said his baby had been sick and died partly from the lack of sufficient heat. (Electric blankets make a tremendous amount of heat. I have one and the dial goes up to 10 but I can't set it above 1, or it's too hot. I wish that guy had thought of an electric blanket, or a friend or hotel.)

So I liked to visit the basement at night anyhow, to see the sheet dryers and whatever else there was. He even let me store a couple boxes of junk down there.

We didn't have enough cold water pressure on the 5th and 6th floors because he didn't know how to use the air pressure system that was already installed when the builidng was built. I found it explained in a book, photocopied it and sent it to him but it didnt' help. There is a holding tank for 2 or 300 gallons of the cold water, and air is pressurized above it to force water more quickly when the top floors want it, especially when a toilet is flushed, but eventually the air gets absorbed by the water and the tank fills with water, and then only the city water pressure is present, and then more air has to be pumped in. There was an automatic pump for that but he wasn't using it. Instead the water pump ran constantly, which iirc it should not have, and it didn't help that much anyhow. This meant that when someone flushed** a toilet, at least in the line for the bathtub I used (my apartment had 2 bathtubs and one shower stall, in 3 bathrooms), it lowered the cold wwater pressure and made the shower too hot if it was okay before. If it was too hot before, it made the combined temp okay, but that meant it was usually too hot, so that's no good. This is when I resumed the habit of taking baths, not showers.

**Because apartments in NYC usually have Flushometers (tm), not tank toilets, and they use all the water for flushing at once.

During this time of not enough heat, I found the furnace room, with a hasp and a padlock, but the doorway was uneven and the hasp couldn't be put on right so that the screws were covered, so I just unscrewed one half of them, into the heavy extruded metal door frame, and the door opened. (When I was done, I'd put back the screws, put some spit on them, and hope they rusted before the super noticed anyone had removed them. I think that worked.) Inside I found the smoke sensor that was intended to turn off the furnace for the whole 49 apartment building, if there were too much smoke in the furnace room, and when I opened its door and took off the cover plate, I could see that it had been hotwired so it would never turn off anything. Naughty, naughty.

The oil supply pipe to the furnace leaked and rather than fix it, they had a plastic dishpan underneath it catching the drip. I told you he wasn't a very good plumber.

And then I found the heat control box. it didn't have temeperatures, only letters, A, B, C, D, E, F. Whatever it was set on, I turned it one more setting, like from C to D, then loosened the set screw for the knob, pointed the knob at C again, and tightened the screw. After that, by golly, we had more heat. There was no one in the building I could tell about this, so when I moved a few years later, I didn't tell anyone,

Eventually they must have gotten suspicious of something and they put in a key switch in the elevator panel in place of the button for the basement. 2 in the morning, I took off the heavy brass escutcheon plate for all the buttons and ran some lamp cord from each side of the key switch, which had convenient screw terminals, so it ended just at the edge of the brass cover plate. Then all I had to do was touch a quarter to the raw ends of the lamp cord and I would go to the basement. I could only do this late at night, or the super might notice me there. The buttons are on low voltage so there was no risk to anyone.

I didn't tell anyone about the elevetaor controls either when I left but when I was back 20 years later, they had found that wire and taken it out. ....

Of course I could when I connected the plug.

Did she speak English?

And was she 13 years old ?

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