LED lighting

Significantly LESS than any incandescent bulbs.

Think of it this way - I have about 100 bulbs on my layout.  If they were all incandescent it would take an entire ZW to power just the bulbs.  With LEDs I could power the bulbs and run a couple of trains with a ZW.

If using LED's in scenery other layout stuff, don't use track power, use a separate DC power supply. Actually makes things simpler. Refitting rolling stock to LED has savings and reliability as well, but as for me, I don't refit LED's in any original prewar stuff. It just ruins the original fabric and nostalgic look. BTW those miniature incandescents draw somewhere around .25 amps (YMMV), a typical LED will draw around .015-.020 amps (YMMV) 

To each his/her own I guess. Just yesterday I got my first switcher, a postwar 41, that was in truly excellent condition and very little track time as far as I can see. I put it on my test track and saw it had no light. I put in a 3mm warm white LED, taping it behind the lens, and it looks great. I also glued in, with easy to remove glue, an engineer in the cab.  The updates took all of 5 minutes and can be easily backed out.

It depends on how many LEDs are being used. Less than 50, not much.

We have hundreds of LEDs and prefer to use separate transformers from Evan Designs. Give Dave a call and he will get help you based on what your projected needs are.

Dave might be a bit more expensive than some but in all our years of using his LEDs, only one was bad and was quickly replaced. They are good people to deal with.

Hope that this helps.

You can purchase a large variety of LED's designed as Lionel replacements that run on AC from Town and Country with both screw and bayonet bases.   You just screw out and screw in.  It's that simple.  https://stores.towncountryhobbies.com/leds/

The best advice IMHO as already mentioned is to power all accessories, switches and lighting off supplies separate from the trains.   I use 14 VAC transformers to power accessories and switches.  I use 12 VDC for building lights, street lights, etc.  I use practically all LEDs.  I run the trains on two ZW's.

I use the 14V accessory posts of my two MTH Z1000 transformers to run two large distribution blocks that then power all accessories including switches. With command control, this is the recommended method.

I am one who uses a separate Powerhouse for lighting, previously had switches and lighting in the same power source, to many brown-outs on the layout when switches thrown.

Ray