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The fact that I can find hardly anything about running current through galvanized steel suspension cables on Google should probably tell me I shouldn’t do it, but I thought I’d ask here anyway.

I’m messing around with some DIY hanging lamp ideas with 12 V LED strips. I’d like to suspend it from the ceiling, and I like the simple look of the steel cable you can buy from Lowe’s by the foot (1/16 or 1/8 inch). Anyway I have seen many hanging lamp designs suspended in such a way, with an additional, traditional lamp cord powering it.

I know steel is a poor conductor, but I’m wondering if using a <4ft. run I could get away with both suspending and powering the LED strip through a steel cable? It’s 12 V, and probably around 12 watts for the length of LED strip I plan to use in the lamp.

Edit: To clarify what I have in mind. I'm imagining two steel cables coming out of the ceiling ~3 feet apart, running straight down and suspending a 4 ft. horizontal dowel which houses the LED strip. One serving as the positive and the other as the negative lead to the LED strip. All powered from a 12V 40ish Watt transformer.

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    \$\begingroup\$ Just some food for thought, I don't know enough to answer. 12V at 1A would not necessitate a particularly huge steel cable(steel is less conductive than copper so when used as a conductor you simply need a thicker steel cable than the copper cable would need to be for the given current. You must make sure it's safe, ideally out of human reach, but it's likely possible. You may need special materials or connectors where you join copper to steel due to corrosion. The rule is not to bond dissimilar metals, but steel isn't on the periodic table, so I'm not sure what you can bond it to safely. \$\endgroup\$ – K H Apr 29 at 2:09
  • \$\begingroup\$ @KH Thanks! Good info! \$\endgroup\$ – Ryan Apr 29 at 2:36
  • \$\begingroup\$ @RussellMcMahon Thanks for the comment! To be clear, you're saying it will work, but is a bad idea to use an uninsulated steel cable to do this? I essentially had an upside down version of this is mind, with the 2 steel cables suspending a horizontal 4' dowel with the led strip in/on it. These lamps you linked are dangerous? \$\endgroup\$ – Ryan Apr 29 at 2:38
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    \$\begingroup\$ if you power it from a rechargable battery, whether nickel, lead or lithium, they can source enough current to start fires. Protect the wiring with a fuse. \$\endgroup\$ – Neil_UK Apr 29 at 9:03
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    \$\begingroup\$ @RussellMcMahon If you're building it yourself, then a fuse is far more failsafe than any limiter or detector. I used to kick out about fuses when I was a smartass child. I burnt a friend's child badly because a 12 V 7 Ah 'toy' battery was unfused. We underestimate the potential of low voltage circuits to cause harm. So now I tend to mention it a lot more, and use fuses routinely. \$\endgroup\$ – Neil_UK Apr 29 at 11:47
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Can you run low voltage current through galvanized steel suspension cable?

Yes you can.

These lamps use the two steel rods as uninsulated conductors to transfer 12V to the lamp

enter image description here

While yours uses cables, these lamps use the two steel rods as uninsulated conductors to transfer 12V to the lamp !!! eg This and this and this and many of these

Yes you can.
As Drew says - check the resistance.
You can even use 2 cables as the two leads in a circuit - AC or DC.
You can even do it uninsulated (as long as they are insulated from each other.
AND many desklamps with two steel (plated or stainless) rods to suspend the map use the two uninsulated rods as power conductors.
AND you can draw power from the two rods/wires by direct connection - power a device, short out the lamp, burn down the house if you are clever.

ie YES it's done even uninsulated - AND it's a bad idea (but viable with due care). Limiting voltage and current helps.

To be clear, you're saying it will work, but is a bad idea to use an uninsulated steel cable to do this? I essentially had an upside down version of this is mind, with the 2 steel cables suspending a horizontal 4' dowel with the led strip in/on it. These lamps you linked are dangerous?

Everything is dangerous. Some things are more dangerous than others :-) :-(.
I'd consider doing it myself BUT I have a lot of experience in not burning things down :-). The lamps I linked to have been for sale for decades and still are afaik. I'd say that an unknown some house fires would have been caused by them. Maybe not many. Maybe even none.

Your system is safer as it is up out of the way, nothing (usually) interacts with it and the tension keeps the wires aligned. You have to try quite hard to make fire from such a power source (ask me how I know :-) ) but it can be done.
I suggest being aware of the risks (now you more or less are) and be sure that your insurance cover or state of mind is up to whatever the worst case consequences are. If current can be limited to no more than the lamp needs, so much the better. Good would be a monitoring circuit that shut off power if other than a lamp load was detected. Few would bother to do that.

Summary - it's your risk, I'd rate it "safe enough" while noting the possibilities.
Sleeving at least one wire in clear plastic would help heaps Even a heavy clear varnish spray would help improve safety.

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"Sí, se puede"

This should be fine. Some years ago there was trendy lighting that used suspended cables with 24VAC low-voltage bulbs; what you're doing is similar. I suggest this as this could be a source for some of the bits and pieces you might need, even if you don't use their special super-duper expensive stranded cable.

(My suggestion? IKEA makes those 'DIGNITET' cable curtain rods. If you have one laying around unused, that could totally work for suspending a low-voltage wire from a ceiling.)

Safety-wise, it's low-voltage (less than 50VAC) and generally 'touch-safe' based on SELV limits. Since it's indoors, even better.

So... go forth and be your bad self and hang that LED bar.

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  • \$\begingroup\$ In looking for cables intended for this use, I've found only the Tech Lighting brand "Kable Lite" cable light cables which are very expensive. It's literally the only cable i've been able to find that looks like twisted SS, but it's actually "tin-plated copper cable with kevlar core". I've been surprised that I cannot find anything else like it! \$\endgroup\$ – Ryan Apr 29 at 2:52
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    \$\begingroup\$ Have those over my desk at this moment. Converted the halogen bulbs to LED. Probably were trendy/expensive as the other half picked them out. \$\endgroup\$ – Spehro Pefhany Apr 29 at 2:53
  • \$\begingroup\$ I saw an LED pendant light today at Lowe's with a single, very thin, clear coated, round cable running to the bulb. Looked like a metallic mesh under the clear coating. I have to assume it is some kind of coaxial cable. Every heard of coaxial cable used to power LEDs? \$\endgroup\$ – Ryan Apr 29 at 2:59
  • \$\begingroup\$ I reworked my answer, and offer an IKEA hack for the cable. \$\endgroup\$ – hacktastical Apr 29 at 17:14
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You should start by measuring the resistance of the cable. Assuming it's only an ohm or 2 it should work ok. Every ohm of the cable will drop the voltage by 1V at 1A.

You'll want to use the cable as the negative lead so it doesn't short to random objects in the house.

I'd make sure your power supply is one of those "power brick" types ones, and not extremely overrated or god forbid a car battery. Although any of these will work, the car battery for example can supply enough amps to start a fire if something shorts out. Almost all of those black plastic power bricks will simply shutdown if there's a short.

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  • \$\begingroup\$ Thanks for the answer! I'll try to get a resistance measurement. In regards to your second statement, could I use one steel cable as the positive and another as the negative, as long as they can't come in contact? I was planning on using this transformer: amazon.com/dp/B07MSBK9GV/ref=cm_sw_em_r_mt_dp_U_HNoQEbVRY860N Is that sort of what you had in mind? \$\endgroup\$ – Ryan Apr 29 at 2:45
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    \$\begingroup\$ “You'll want to use the cable as the negative lead so it doesn't short to random objects in the house.” Negative relative to what? The power supply is probably galvanically isolated, so its “ground” will be different from other “grounds”. \$\endgroup\$ – Michael Apr 29 at 14:46
  • \$\begingroup\$ @Michael If it's grounded, then negative is better. If it's isolated, then it doesn't matter. \$\endgroup\$ – Drew Apr 29 at 20:40
  • \$\begingroup\$ @Ryan Yes that's probably fine. Just don't us a supply rated for say ~10A. You can use 2 steel cables. The resistance will be the sum of the 2, use that for your calculation. \$\endgroup\$ – Drew Apr 29 at 20:43

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