Call the fire department. They have (most of them do anyway) heat detectors that will find a problem if there is one.
It could be anything from a mouse or bird bringing in a lit cigarette butt for nesting or burning wires/connections.

Agreed. There are so many possibilities, from a loose connection in a junction box to old BX cable trying to deal with a ground fault, that even suggesting a list is impossible. And that's without all the other non-electrical possibilities.

It wouldn't hurt to open the main breaker if you think an electrical cause is likely, but you should get an experienced fire control pro in there NOW.

Please write back and let us know that things are OK.

I used to lurk on this site alot but never felt compelled to register and reply until now.

I'm a firefighter in the Northeast and a few years ago (maybe 2002) we had a call for the same problem and with the thermal imaging camera we found a hot spot under a hardwood floor on the first floor of a 100 year old aprtment building. When we took up the floor we found that a 12" X 12" beam above a renovated basement apartment had been burned/charred almost all the way through. The cause was a staple or nail through a switch leg to a fluorexcent fixture, and the wire was BLUE Romex or NM. The smell happened every morning in the days before we were called, and disappeared after a short time, and sometimes occurred in the evenings for a short time as well. The reason was that it either went to a kitchen or bath and wasn't left on to draw current through it for a very long time, but on the day we were called it had been charred for so many years that it continued to smolder after the occupant left for work. I have never worked with blue Romex because it was only manufactured for a short time I have been told, but I think that the problem existed for years and only became apparent when the charred surface area of the beam became large enough to emit enough smoke to be objectional, and it still did not activate the smoke detectors.

Call the fire department.

I'm sorry for the length of my first post.

Can someone pinpoint the use of blue Romex?

Thanks for a very informative and sobering post. However I'm a bit puzzled about the "blue Romex." It sounds like the cause was the staple in the cable. Are you suggesting that something the design of this particular cable, this "blue Romex," made it especially dangerous?

As for its provenance, I can't help you. I don't think I ever installed any, but I do seem to recall running across a bluish-grey jacketed NM. I don't recall ever seeing an NM jacket I'd describe as blue. But I'm a DIY; the pros would be a lot more likely to have seen something like that.

maybe the blue romex was aluminum?

Is your water heater a gas unit? Your furnace?

If it is, I might have a solution since my first house had this similar problem.
I am also an electrician and I believe your problem is not electrically related. On windy days, I would encounter a downdraft through my chimney and through the hood of my gas water heater. Two problems here - occasional burning smell AND carbon monoxide. Make sure there is a functioning carbon monoxide detector in the areas of the house where you spend most of your time. If you call the fire department and/or the local gas utilities, they can check for elevated CO2 levels.
These burning odors I encountered in my first house were in the colder months when I operated my upstairs fireplace and the damper remained open.
Please let us know what you find!

Yesterday morning had a very definite strong wood burning odor here and I walked around looking at our and neighbors too. About daylight you could see smoke all around much like a sea fog.

Apparently lots of wildfires in florida and georgia right now and wind can carry some of that smoke and odors hundreds of miles at times.

News said calls to 911 had doubled with 'somethings on fire, somewhere' calls.

I mentioned the colored Romex because I had never seen it before (or since) but the Electrical Inspector said that it was manufactured and installed in the 70's or 80's. This was the timeframe in which the building had been re-habbed and was probably when the cable was compromised. I wanted to give some idea of the length of time that the smolder/non-smolder cycle had been going on.

In Canada at least aluminum romex was blue coloured. Although I think the problem was not the fact that it was aluminum but hte fact that a staple damaged the wire.

Did you use cloth dryer at the time??Most house fires are due
to restricted filter and lint in gas and electric dryers.

According to the CDC, unattended or careless cooking is the leading cause of fires. Smoking is the leading cause of fire deaths.

The CDC doesn't mention clothes dryers as a cause. However, this page lists NFPA annual averages for fires between 1999 and 2002.

Anually :

• 126,800 fires attributable to cooking resulted in 280 deaths.
• 35,000 fires attributable to smoking resulted in 890 deaths.
• 17,800 fires attributable to clothes dryers or washers resulted in 10 deaths.

Candles caused more fires (20,900) and far more deaths (170) than washers and dryers.

This doesn't mean you should be careless about keeping the dryer vent clean, just that it's not a leading cause of fires.

Is the smell coming from the outside? If you smell it, go outside and see if you smell anything. In my previous house, when my neighbor used his wood burning fireplace, smells would migrate through the gable vents and in through non-airtight recessed light fixtures. Just one more thing to consider. Let us know what you find.

I would like to thank everyone for their advice and concern. She said that the smell has not occurred except as originally described. I suggested that she not let this go and to have the FD and an electrician check it out. I hope she does so.

We're in Florida and occasionally the last few days you can catch a whiff of smoke from the fires that have been burning in the state. Although not real close, I've heard the smell can be detected hundreds of miles away if the wind in blowing in the right direction. If that were the case you would think the smell would be outside and not inside though.

Thanks again. IÂll provide another update should anything be discovered.

I am reading this post because I smell a smokey smell in my home and it smells like electrical. I turned off the breaker for the ceiling lights in my over 100 year home because the smell seemed to eminate from the ceiling. I still can smell this awful smell. It comes and goes throughout the day however I want to eliminate it. I want to know if the fire department would charge me to see if I have a "hot spot".

Thanks