Is Fire Conductive Enough To Power A Lamp?

Is fire conductive? As ridiculous that may sound at first glance, from a physics perspective the rapid oxidation process we call ‘fire’ produces a lot of substances that can reduce the electrical insulating (dielectric) properties of air. Is this change enough to allow for significant current to pass? To test this, [The Action Lab] on YouTube ran some experiments after being called out on this apparent fact in the comments to an earlier video.

Ultimately what you need to make ‘fire’ conductive is to have an appreciable amount of plasma to reduce the dielectric constant, which means that you cannot just use any rapid oxidation process. In the demonstration with lights and what appears to be a (relatively clean-burning) butane torch, the current conducted is not enough to light up an incandescent or LED light bulb, but can light up a 5 mm LED. When using his arm as a de-facto sensor, it does not conduct enough current to be noticeable.

The more interesting experiment here demonstrates the difference in dielectric breakdown of air at different temperatures. As the dielectric constant for hot air is much lower than for room temperature air, even a clean burning torch is enough to register on a multimeter. Ultimately this seems to be the biggest hazard with fire around exposed (HV) electrical systems, as the ionic density of most types of fire just isn’t high enough.

To reliably strike a conductive plasma arc, you’d need something like explosive (copper) wire and a few thousand joules to pump through it.

16 thoughts on “Is Fire Conductive Enough To Power A Lamp?

  1. Shocking thumbnail presenting some dude going at mains cables with a blowtorch means I won’t even bother to watch the video. To hell with Your Tube clickbaity earnings, I have better things to do.

    1. On one hand I were almost gonna make a post about how the ionization happening during combustion is how some modern cars use their ignition coils to detect per-cylinder detonation.

      But on the other hand, that kind of video clickbait only deserves to be chastised, because it further accelerates the clickbait trend through “it’s OK if I do it” mentality.

  2. “what appears to be a (relatively clean-burning) butane torch” Relatively? M’kay. Water and carbon dioxide.

    I question the assertion was even in the building; flame yes.

    1. Sorry, my bad. “I question the assertion that there was even plasma in the building. Flame, yes.” That said I’m arguing from ignorance, where I am most at home.

  3. I’m also not viewing the video because, frankly, the guy give me the creeps.

    So I don’t know what they guy actually says, but I have to point that out the idea that to use “plasma to reduce the dielectric constant” is not correct.

    First, the dielectric constant of air is pretty close to that of vacuum. Nothing you can add can reduce it.

    It might be more correct to say “reduce the dielectric strength“, but even that isn’t what’s happening: The flame just adds ions and free electrons that reduces the resistivity of air. Its dielectric constant has nothing to do with it.

  4. I had a refrigerator that stopped running, but the light worked, and on close examination of the wall socket conection, I could see a tiny gap
    had developed where a conection was loose, less than.a piece of paper is thick, and the light worked, but not the compressor, tightening that fixed the problem.
    Had a similar thing with a blower motor, where there was a gap in a conection, but it ran, with a kind of frying sound.
    And its possible to get a big fat arc from solar pannels,when wireing
    them up, as the open circuit voltage with a few in series is fairly high and
    the amps can be well over name plate, depending on conditions:ie edge of cloud.
    Though it occurs to me that what the discusdion is centered on, might be a way to get an explosive reaction with a heavily excess fuel flame.
    Not that I care, I am the danger coordinator, saftey 3’rd, but for those who are not used to high energy release at close quarters, this is not the best place to start.
    And on topic, this is the same phenominon that blocks radio from space craft durring re-entry into the atmosphere, or did, as I think the big domes at spacex or one of there contractors has figured out a way to transmit through the ionised flame of re-entering space craft.

    1. I recall that sometime back in the 70s the US military sponsored research to see if flame/arc generated plasmas could be used to create deployable on demand radio antennas. As far as I’m aware the idea never seems to have gone anywhere.

  5. At least we know the reason why a fire department will pull the electric meter off a house that is on fire: that current going into the house will contribute to the fire.

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