Low Voltage Question

[Rtrorkt]

For the brain trust. Installed yard lights down stream from my transformer. Low voltage LED fixtures. Worked well, then my connection go wet and no go. Have pulled the wiring from the ground and was testing. Lights flicker. On touching the wire, it was hot, very hot to the touch. I thought there is little current running through so I am surprised at the heat. Transformer is rated for many more fixtures than I have on the line. Now have four plus the two in question

Will re-splice all connections and heat shrink them again. Thoughts on why the wire was hot?

[flatbutt]

Will a ground of some sort cause current to keep flowing and produce heat?

[Baz]

It's a misconception that low voltage will not produce heat when wires are crossed. That is what is happening there. You have to go back over everything and find the short.

Can be tedious but with your simple system not bad. Just be thorough and you'll find the issue.

Potential issues: transformer, cable, LED fixtures, LED bulbs, connections.

I don't heat shrink my connections - I use wire nuts filled with dielectric grease.

[Rtrorkt]

Thank you Baz. So, I have a cross connect positive/negative. I can fix that. I have tried wire nuts with the dielectric grease, but those did not work for an extended period. Its in an area around a fountain that has proven beyond troublesome.

Will just get out there and reconnect things.

[Rtrorkt]

Baz, one more question. It appears as though the two wires on the fixture have differing wire color. Assuming I keep like to like to be sure. Will it matter when I connect them to the main power wire coming from the transformer? Not sure how that wire is connected, which side to which pole.

[Baz]

Originally Posted by Rtrorkt

Baz, one more question. It appears as though the two wires on the fixture have differing wire color. Assuming I keep like to like to be sure. Will it matter when I connect them to the main power wire coming from the transformer? Not sure how that wire is connected, which side to which pole.

No, it won't matter which side is connected. Wire is wire. The wires just can't touch each other, obviously. Otherwise, no such thing as positive and negative to keep track of. Hope that helps, Rocketman!

[Rtrorkt]

yep, I'm on it. And for that advice, a little remake of Peter Green's Station Man, Pete Townsend playing

[Baz]

Thanks, brother. My fav. song off Kiln House. And PT is great!

[mjohnson]

Originally Posted by Baz

It's a misconception that low voltage will not produce heat ...

Heh. I was making tantalum carbide in school with a vacuum furnace that ran at 6V. There was however about 2000 amps though going through those graphite heating elements. It was at least 1800C - the peephole in the door projected a nearly white light across the room.

The safety lesson was, besides the heat and the (related) importance of keeping the cooling water on, you can touch the conductors but for god's sake don't drop a wrench on them. You'll get blowed up.

Electricity is strange...

[pwd72s]

Before the heat shrink use some dielectric grease. I suggest a brand callled super lube.

[908/930]

Was the entire cable hot or just the where the joint is? If it is the wire getting hot, is it rated for direct burial?

[masraum]

Originally Posted by flatbutt

Will a ground of some sort cause current to keep flowing and produce heat?

my first thought. heat in a circuit = short.

[masraum]

Originally Posted by Baz

It's a misconception that low voltage will not produce heat when wires are crossed. That is what is happening there. You have to go back over everything and find the short.

Can be tedious but with your simple system not bad. Just be thorough and you'll find the issue.

Potential issues: transformer, cable, LED fixtures, LED bulbs, connections.

I don't heat shrink my connections - I use wire nuts filled with dielectric grease.

[Rtrorkt]

Couldn't see my mistake when I first pulled is apart. I now have the fee cable (2 wires) and the two low voltage fixtures with 2 wires a piece When the sun quits hitting the site (105 right now) I will carefully connect two of the fixture wires to one of the feed, heat shrink and electric tape wrap, then do the other 2 fixture wires to the feed. Repeat.

May even send a pic or two so the brain trust can tell me what I am doing wrong.

[masraum]

Originally Posted by Rtrorkt

Thank you Baz. So, I have a cross connect positive/negative. I can fix that. I have tried wire nuts with the dielectric grease, but those did not work for an extended period. Its in an area around a fountain that has proven beyond troublesome.

Will just get out there and reconnect things.

I wonder if the liquid electrical tape stuff would do a good job of sealing the connections from moisture. I used it on coax cable for TV many years ago (I kept planting stuff and forgetting about the cable. ) and it seemed to work.

[Rtrorkt]

Couldn't see my mistake when I first pulled is apart. I now have the fee cable (2 wires) and the two low voltage fixtures with 2 wires a piece When the sun quits hitting the site (105 right now) I will carefully connect two of the fixture wires to one of the feed, heat shrink and electric tape wrap, then do the other 2 fixture wires to the feed. Repeat. All rated for direct burial.

Wire was hottest near the connections, but warm for a bit of a distance

May even send a pic or two so the brain trust can tell me what I am doing wrong.

[908/930]

Any resistance in the line or joints will likely create heat, if you can, twist the wire tight and solder it, then wrap it to protect from moisture. how many Amps are each LED light and how many lights?

[red-beard]

Originally Posted by Baz

It's a misconception that low voltage will not produce heat when wires are crossed. That is what is happening there. You have to go back over everything and find the short.

Can be tedious but with your simple system not bad. Just be thorough and you'll find the issue.

Potential issues: transformer, cable, LED fixtures, LED bulbs, connections.

I don't heat shrink my connections - I use wire nuts filled with dielectric grease.

heat comes from current and resistance

P = I^2 * R

If there is a short or really a ground, it will heat up the wire. If you have a wire smaller than the rating of the transformer, it could heat up to the point of fire.

[Baz]

Photos are always helpful.

Also, there is a way to troubleshoot where certain components can be eliminated as the problem.

Start with transformer - measure output in volts. 12v? Good.

Hook up cable and connect to known good light fixture. Comes on OK? Good.

Now you know the transformer and cable are OK.

One by one re-connect each fixture.


Other than that - the problem might be associate with a deterioration of your components and/or connections due to weather and natural elements.

Like I said earlier - it's very basic and should be straight forward to toubleshoot...

[john70t]

Originally Posted by mjohnson

Heh. I was making tantalum carbide in school with a vacuum furnace that ran at 6V.

Electricity is strange...

At a youthful hangout party...a bunch of kids sat on a dented hood...which somehow connected down to the (12V+) battery terminal.
A five foot fountain of sparks with a small hole burning through the hood followed.

I think it only takes 1/10th amp to stop the human heart.

(and yet Tesla could repeatedly shoot lightning from his fingertips)