gluing electric blanket wiring for DIY blanket?

Try it on a little piece.

What you mean: you "can't sew"? How difficult can it be? Are you aiming to produce something decorative?

Alternative: buy some iron-on tape and glue it around the cable without trying to attach to the cable itself. So the cable is in a pocket. The cable will not get so hot that it opens up the pocket; if it does that the whole project is too dangerous!

Let's not get ahead of ourselves. 8 minutes before posting this you asked (on S.E.R) how to get the resistance of your wire. Without the resistance, you must be assuming that the 40w will come from a 3.3A, 12v power supply. But with very low resistance (as your wire almost certainly is*), you'll get your 3.3A, but at a much reduced voltage (assuming that the PS doesn't shut down on over current). Then you'll have much less than 40W & you'll be cold .

To get the 40w from your 3.3A (assumed), 12v supply, your wire's total resistance would have to be 12/3.3 = 3.6R. Once you know the resistance per foot of your wire, you can figure how long it will have to be. For copper wire of reasonable size, that could be 100's of feet.

• - electric blanket wire is different than regular wire - it's resistance (per foot) is much higher. I salvaged some wire from an old blanket and its resistance was/is an ohm per foot. 50 times greater than 22ga copper wire at .02 ohms per foot.

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I figured it out and I'm laying under it now. I didn't like the amount of power that was being generated at 12 V (84 watts), so I went with 5 V

and did a quick and dirty method of checking amps as wire length was reduced. It turned out that 20 feet of the wire uses 11 amps at 5 V. So, I took the 20 feet and glued it in a zig zag pattern on the blanket with the hot glue. After two hours of continuous use, absolutely no melting of the hot glue so far and the connections are cool. The warmest part outside of the blanket is actually the wire leading to the power supply. I borrowed the original wire that was with the Sunbeam blanket, but its gauge seems to be thin. If it gets too warm, I'll have

to upgrade the power wire to something thicker.

I guess one good thing here is that I will need an additional blanket or

two covering the electric blanket once the house gets colder. It's 63 F

in here now and I have a dollar store fleece blanket on top and I'm comfy .

I did notice something during my experiments. I at first applied 12 V through the entire wire length (I think it's 60 feet or so but not certain). At 12 V, there was 7 A used. Although wattage was more, the wire seemed cooler than it is now at 55 W @ 20 feet. My guess is because less wire means more power per foot even with less wattage than there was at 84 W.

If I would have had a cheap way to control output, I would have gone with the 84 watt version. All I had on hand was a PWM dimmer used for dimming LED light arrays. Although rated for 12 V @ 8 A, it burned up almost instantly. I wasn't surprised, but not sure what I would have used to vary output.

I have vivid memories of an electric blanket starting a fire in my parent's bedroom when I was a kid. How confident are you that you can can be more fire-safe than an commercially produced one?

Even if it doesn't melt in use, I don't think hot melt glue will hold up well to repeated movement.

Sewing is not hard. Easier than sewing? Fill a hot water bottle from the kettle and put it in the bed every night.

Elijah

------ selected an extra large kettle for the hot water bottle needs

You won't be gluing teflon wires with hot-melt glue - the glue won't stick.

Teflon melts at something like 500 F, and teflon-based fabric used for radomes and enclosed tennis courts are bonded using a lower-melting kind of teflon as a "brazing" alloy.

Joe Gwinn

You won't *glue* the wire, as such, more embed it in a blob of plastic -- as long as hot-melt goes under AND over the wire :)