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  • theant commented on happydupa's instructable Inexpensive garage lights from LED strips5 months ago
    Inexpensive garage lights from LED strips

    Sounds like a couple of close calls. It also sounds like you had a good idea with the copper/aluminum connections. I vaguely remember some converting the attic to copper leaving aluminum in the walls but always felt a bit concerned with that because the aluminum is still there and in the tighter spaces but more importantly dissimilar metals, differing coefficients of thermal expansion and potential galvanic effects causing accelerated corrosion. This is the first mention of conductive grease I had heard of and maybe they did that back in the day as well, idk. I guess that the grease eliminates air contact and so oxidation, is that correct?I also thought most of the troubles occurred in the light switches where again there are dissimilar metals. The galvanic effect varies depending on th...see more »Sounds like a couple of close calls. It also sounds like you had a good idea with the copper/aluminum connections. I vaguely remember some converting the attic to copper leaving aluminum in the walls but always felt a bit concerned with that because the aluminum is still there and in the tighter spaces but more importantly dissimilar metals, differing coefficients of thermal expansion and potential galvanic effects causing accelerated corrosion. This is the first mention of conductive grease I had heard of and maybe they did that back in the day as well, idk. I guess that the grease eliminates air contact and so oxidation, is that correct?I also thought most of the troubles occurred in the light switches where again there are dissimilar metals. The galvanic effect varies depending on the metals used though and all of the above may be a non-issue. Just never got into ot that deeplySorry to talk like I am teaching the folks who replied to me because you may well know more about some of this stuff than I do. The details and thought fodder are meant for those who might be interested and that I am "ate up" with the ADD and think better as I talk or type. Not that ADD is an all bad thing. We tend to be interested in pretty much everything and keep in mind more variables than "normal" folks. Different folks, different problems and different gifts and everyone deserves respect whether you know their gifts or not. Thanks for the input folks! It all goes into our experiences!

    Nice job and great ideas!

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  • theant commented on happydupa's instructable Inexpensive garage lights from LED strips5 months ago
    Inexpensive garage lights from LED strips

    I didn't know about the oxygen tank thing. I think there's a danger of using the wrong kind of oil on the fittings, not sure. What brought it to mind to me was aluminum wiring in houses that had the innate high coefficient of thermal expansion tat meant a movement with temperature that would expose clean aluminum to the air and then it would draw back depending on temperature. It could cause a loosening I suppose but I think the real problem was that oxidized surfaces on aluminum are more resistive than a new,clean connection. The resistance of course is a heat generator, which inherently promotes oxidation. Arcs, I suppose eventually might occur and that heat is high enough to ignite the aluminum or nearby materials, maybe in some cases insulation, not sure. None of this is to take awa...see more »I didn't know about the oxygen tank thing. I think there's a danger of using the wrong kind of oil on the fittings, not sure. What brought it to mind to me was aluminum wiring in houses that had the innate high coefficient of thermal expansion tat meant a movement with temperature that would expose clean aluminum to the air and then it would draw back depending on temperature. It could cause a loosening I suppose but I think the real problem was that oxidized surfaces on aluminum are more resistive than a new,clean connection. The resistance of course is a heat generator, which inherently promotes oxidation. Arcs, I suppose eventually might occur and that heat is high enough to ignite the aluminum or nearby materials, maybe in some cases insulation, not sure. None of this is to take away from the practical points of JohnW51, just things to think about. BTW, any adhesive may be flammable of course and they vary on heat transfer capability, the better stuff of course costing more money. A real benefit to me of LEDs is that with a DC power supply they aren't doing a constant 120 flashes every second (each side of the 60Hz AC Wave) like fluorescents making s crazier.

    Ahh, so you want me to think? You beast, you, heh! Tape has less heat capacity per the LED contact footprint but maybe enough heat transfer capability, that is, heat conductivity. It would better suffice for the purpose of extending life of LEDs by keeping them cooler, but actually absorbing a quick flash of heat requires high heat conductivity. Depending on the duration of the high heat (quantity), capacity becomes more important. The longer and hotter, of course, also indicates need for capacity. If one would want to get UL approval picky, aluminum as a heat conductive material would have to have some scrutiny because aluminum catches fire at a lower temperature than say, copper or tin. I do not know the characteristics of the LED and the ribbon, etc., in some kind of burn failure. Th...see more »Ahh, so you want me to think? You beast, you, heh! Tape has less heat capacity per the LED contact footprint but maybe enough heat transfer capability, that is, heat conductivity. It would better suffice for the purpose of extending life of LEDs by keeping them cooler, but actually absorbing a quick flash of heat requires high heat conductivity. Depending on the duration of the high heat (quantity), capacity becomes more important. The longer and hotter, of course, also indicates need for capacity. If one would want to get UL approval picky, aluminum as a heat conductive material would have to have some scrutiny because aluminum catches fire at a lower temperature than say, copper or tin. I do not know the characteristics of the LED and the ribbon, etc., in some kind of burn failure. The anal retentive aside, it was just food for thought and I wanted folks to think about fire safety when designing stuff, especially mounted on wood. Respectfully, TheAnt

    Please also consider catastrophic failure of electronic components. A heatsink would likely absorb a single LED "flash fire" but also consider that wood becomes kindling in hot and dry climates.Just a thought though... the air conditioning metal tape might be an excellent heatsink, cheap, and easy to apply. Most any tape will adhere well to the smooth metal side.

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