DiyLightAnimation
Fun => The Porch => Topic started by: chrisatpsu on January 09, 2013,
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in my plans I'm working on for next year, I need to know how many amps i can send through either regular spt1 or spt2 wire at 12v DC.
yeah, i know the spt1 or 2 is just the insulation on the wire, but whatever your basic standard gauge wire that happens to be spt1 or 2.
and the number you're answering with, is it the max, or an 80% or 90% figure?
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go to this site http://www.powerstream.com/Wire_Size.htm
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As much as you can until it melts then back down a couple of amps! :o
I AM just kidding!!!! <fp. >:D
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It dependes on the length and if they are bundeled together
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30ft maximum, and that's only if i can support a lot of amps... single wire (2 conductor) either connected to the power connector of an active hub, or powered from a 12v power supply from Ray...
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http://www.christmascarolina.com/forums/electrical/2163-facts-about-spt-wire.html says
SPT 1 20 AWG is rated for7 Amps (some manufacturers say 2 amps)
SPT1 18 AWG is rated for 10 Amps
SPT2 18 AWG is rated for 10 Amps.
SPT2 16 AWG is rated for 13 Amps
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Bundling cables affects only AC lines, DC- there is no derating factor ( no induced voltage from colapsing fields across parallel conductors)
Kinda raises my curiosity when someone asks "whats the max I can......."
Be safe.
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What is your definition of a lot of amps? I would say that you could push 15 without much issue. I would guess that these wires are going to be outside.
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so for 18 AWG wire, then 20A @ 12 volts DC for a abput 20ft is a bad idea?
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The part I have trouble wrapping my head around is...
SPT1 18 AWG is rated for 10 Amps
SPT2 18 AWG is rated for 10 Amps.
10A @ 12 volts DC is considerably less power, than say 10A @ 120 volts AC - one is 120 watts, one is 1200 watts.
yet the wire can only handle 10A regardless of the voltage?
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18 AWG for 20ft might be ok. It may get warm but if it's outside, who cares. You may have a bigger issue with voltage drop. You could always set up a lenght and test it. See how warm it gets and how much of a voltage drop you are getting. If the wire is getting hot or the drop is unacceptable, you could always double up on the wire and zip tie them together.
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does doubling up on the wire double my capacity? or not quite?
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Yes, it will double the capacity.
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Amps is a measure of actual electron flow. The max current is a fudge based on the cross sectional area (gauge), reasonable heat dissipation, and the amount of voltage drop you are going to see at the end of the wire (the wire is not a perfect conductor - there is a conductance number that is calculated based on the material the wire is made of and the cross sectional area. You multiply this by the length of the wire to figure the equivalent resistance, which can then be used to calculate the voltage drop at the end of the wire when under full load.)
To run 20 amps ~ 25 feet, I would suggest 12 gauge wire... If you are going 50 feet or more, you should up it to 10 gauge.
The great thing about using 12v systems to power our stings is that we can tolerate about a 4 to 5 volt drop in the line voltage before things start shutting down. If you are using a 5 volt system, even a 2 volt drop is gonna cause problems.
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so for 18 AWG wire, then 20A @ 12 volts DC for a abput 20ft is a bad idea?
Not at all; it's a great idea if you are building a heater.
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Looking at a chart on line, 18AWG copper wire has a resistance of 0.00639 ohms per foot. Multiplying by 40 (2 conductors (+ and -) times 20 feet) gives a resistance of 0.2556 ohms. At 20A, Ohm's law says that you will drop 20 * .256 = 5.112 volts in the wire. That means your lights will only see 6.9V, which may be an issue. Also, your wire will be dissipating 20 * 5.112 = 102W. It will get warm; each foot will dissipate 5W.
Retrying this with 14AWG (.002525 ohms per foot) gives a 2V drop and 40W dissipated in the wire.
/mike
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I ran spt 2 to my gutters from the hub to 3 break away boxes with 4 port passive hubs. This powered 92 feet of flex strips along all the gutters. I probably had maybe 60 to 70 feet run to the furthest break out box. Everything ran cool including the 750 watt power supply, but I did feel it wasn't as intense as it should have been. I'll be running seperate power supplys per box next year.
You can check it out here. I have done a behind the sceans video I'll post soon. (work <fp.)
http://diylightanimation.com/index.php?topic=10961.0
animal
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This is one of the tradeoffs for working with 12VDC vs. 120VAC. I did some research for a using 350W 12VDC power supply for a MR16. IIRC I needed 10AWG to properly feed a MR16... OR double up... The spade connectors for power don't really allow doubling.
(Highjacking thread - GET YER HANDS IN THE AIR!)
If my spider senses are tingling right there is gonna be ALOT of people planning on using MR16s this year for dumb gear. I also think most of these folks will use Ray's connectors too. It would real nice to update the board for better input and output power connectors, like those on the LE since they are going to be popular. Maybe same input power connector and 2 rows term strips to keep same form? Am I alone? One of the weakest areas of my hardware was bad crimping or spade connectors coming off my MR16 during setup.
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This is one of the tradeoffs for working with 12VDC vs. 120VAC. I did some research for a using 350W 12VDC power supply for a MR16. IIRC I needed 10AWG to properly feed a MR16... OR double up... The spade connectors for power don't really allow doubling.
(Highjacking thread - GET YER HANDS IN THE AIR!)
If my spider senses are tingling right there is gonna be ALOT of people planning on using MR16s this year for dumb gear. I also think most of these folks will use Ray's connectors too. It would real nice to update the board for better input and output power connectors, like those on the LE since they are going to be popular. Maybe same input power connector and 2 rows term strips to keep same form? Am I alone? One of the weakest areas of my hardware was bad crimping or spade connectors coming off my MR16 during setup.
I used a combination of MR16s and Ray's 27-channel DMX controllers. In each I attached 4-pin water-proof connectors. For the MR16s I attached the spade connectors, for Ray's I just screwed them down to the board.
I created water-proof extensions (to extend to the RGB lighting elements) using the 4-pin connectors and 20-awg wiring, using soldering and shrink tubing.
I also use a lot of power-over cat5 and 3-channel DMX controllers to light elements when having embedded controllers makes sense.
This thread about diminished power levels has me thinking now... but I don't know if I'll do anything different. I will probably notice the difference in intensity (now that it has been mentioned), but I'll add it to the list of things that annoy me about my display (but are not noticed by anyone else).
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Wow Steve, thanks. Never knew the 27 channel controllers were 12/24VDC, thought they were 120VAC...
Just did some digging and I didn't realize how many folks are using them. I guess they must be decent. Must be used in first universe, right? Also about half the output capacity as the MR16. Not they I need it.
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dmx devices you can use in any universe
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Great. I will explore that.