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What guage wire for 50 LEDs


Stingray
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We are making snow flakes to hang in trees that will have a strand of 50 LEDs on each. I have saved male and female plugs from old light sets. The snow flakes will hang high in trees so I will need a lot of wire to power each one. I beleive the female plugs have 5 amp fuses in them. I have found info that suggests 22 awg wire is good for 5 amps so the salvaged plugs with 5 amp plugs should protect the wire. I have read on the forum that someone used thermostat wire for some of their displays. Anyone have any input on this.

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I presume you will be putting an bridge rectifier in the circuit between the plug and the first LEDs? Wondering what color LED you will be using? If it is white of some flavor, then you might find you can only put about 46 in series. I have experience doing this. I am not real thrilled myself of using a 5 amp fuse. The LEDs usually use about .02 amps per series circuit. If you have something closer to 2 amps I would feel better.

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A lot of people make the mistake of thinking that LED's are lights. They are NOT. They are Light Emitting Diodes. So, just connecting them to a 110v source will cook them instantly. As MaxPaul stated, the rectifier has to be in the correct place along with correct wiring. Note that some LED colors require different voltages as opposed to others. Its probably best if you just buy the led strings that you need for your display and go from there.

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dgrant thanks for bring up a few points that I didnt. The only reason I use a full wave bridge is cause I dont want the flickering with a half wave set-up. I have actually converted some spiral trees that has sections of 50 lamps. Using white LEDs I found that Ican only use 46 in series with no resistors. But if it had been red, orange, or yellow I would have had all 50 LEDs and a resistor to limit the current to about 20ma. Well cause there is no filter cap in the circuit. One has to take into account the Peak voltage and Peak current. So, take 20 times .707 and you get something closer to 15ma. on a RMS meter. This stuff is not pure DC so one has to get their head wrapped around the fact that you have a A.C. signal riding on a

D.C. current.

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Lets also add a basic item for the OP and any others, LED's are polarized. You cannot just plug them in, in any direction like incandescent lamps. This is due to the DC signal as MaxPaul was talking about as well as drop down resistors on "each" LED. All this plus the fact that they are a DC item, means polarity is critical.

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Are these snowflakes store bought and run on AC, or are these homemade and thus the discussion above? Thermostat wire is solid core and breaks easy and not for AC use. SPT 1 wire will do fine. Wind in the tree will be your worst enemy.

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Dgrant,

Now I might have read your last post wrong. But I will say a few things that either clears up what you said or contrast it.

You only NEED one resistor per circuit. Now a circuit could be one or many LEDs in that circuit. Now you can have more than one resistor in that circuit for the reason that you want to use lower wattage resistors that generate less heat. Example just pulling numbers to demonstrate what I am talking about. Lets say you need 1000 ohms total resistance at 1 watt. You could have two 500 ohms at .5 watt, or 250 ohms at .25 watts or 10 times 100 ohms at .1 watt. You will see this in a section of LED Rope light.

And as Dgrant pointed out LED are polarity devices. So, all LEDs in a circuit will need to be aligned in the same polarity direction. Does anyone know how they made those color fade strings that was semi poplar a few years ago? It is two different colored LEDs on the same die and with reversed leads. A controller turns on either the positive or negative halves of the wave or a mixture of both. Thus you have say Red or Yellow or a mixture of both.

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I do know that a voltage drop resistor must be used on every led for it to work. Now whether the resistor is placed on each led or a group, doesn't matter as far as it working, other than the wiring itself that accomplishes the task. One thing I've never learned is how they make two different colors on a led.

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I guess I wasn't clear in my OP. I am going to use a string of LEDs designed to run on AC. I will not be making my own rectifier. I was simply asking if using 22 awg for about a 30 ft run of AC fused at 5 amps seemed legit. I am well aware of the need for stranded wire where vibration or movement is present. I have purchased 22 awg security wire which is stranded. I realize spt 1 will work as I have used 500 ft. in my display so far. In this case as Paul has pointed out the power consumption of 50 leds is minimal and each snowflake will use 30 ft so 22awg will be about half the cost of spt-1.

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Sorry that we have drifted away from your question. As for 22ga wire carrying 5 amps. That sounds a wee bit high, but I have been proven wrong before. If there is going to be only one snowflake on one wire, I would go with no more than a 1 amp fuse. Now 30' of wire might be ok as far as voltage drop. 50 or 60 might be pushing it as far as voltage drop.

Hope that was of use to you.

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