environmentallights.com has a nice calculator for dc voltage drops (even if you don't buy from them)

Here is a link that might be useful: wire gauge calc

Hi, David! I used similar calculator to calculate the wire gauge needed. But, I assume these calculators caculate gauge and dc voltage drop for low voltage dc wire.

I guess my question really is whether a 18 gauge lamp wire( which is for 110v ac) is the same as a 18 gauge low voltage dc wire? If they are not the same, then the dc voltage drop calculator would not apply to lamp wire.

Sara,

There is really no difference in the wire.

18 gauge solid wire would work fine and should be cheaper than lamp wiring.

"I guess my question really is whether a 18 gauge lamp wire( which is for 110v ac) is the same as a 18 gauge low voltage dc wire?"

The voltage drop is based on the physical size of the wire, every 18 gauge wire behaves the same.

Occasionally stranded can be larger than minimum gauge size do to rounding in dimensions, but the effect is very small.

Thank you, David and brickeyee! I know I can always count on your expertise.

I have another question: Leviton magnetic dimmers vs. lutron magnetic dimmers.

There are quite a few brands of magnetic low voltage transformers listing Lutron magnetic dimmers as their approved dimmer, but not leviton magnetic dimmers. I specifically asked Juno whether their magnetic transformer works with other brands of magnetic dimmer, for example, leviton. Their answer is "Unfortunately, at this time, we do not have any Leviton dimmers approved for use with the magnetic TL575 driver. " So basically no information there. I can see leviton is not listed myself!

One of things I learn from this forum is that a magnetic dimmer should work with a magnetic transformer. Any reason why I shouldn't use a Leviton magnetic dimmer with a Juno magnetic transformer? Lutron is much more expensive than Leviton, what I am trading off by using a less expensive leviton?

I am going to post this as a sperate posting just in case you don't see this.