Ah, the Pandora's Box of lighting: do we light it fully, keep it play-able, or try for both?  Great post, and an essential question I think both us in "AFOL land" and the blokes at BrickStuff both tackle regularly.

I recall seeing some working efforts of the BrickStuff folks with power that can run through floors/levels (think tin foil on the stud and the next-up floor), but my recollection is this is/was all still prototype. Magnets are intriguing, but I think the bigger challenge is routing power upwards in floors (if I recall, the magnet is more a sensor for trains and such to toggle a state from off to on, or vice versa...?)

The Disney castle kit had some "quick connect" plugs (awesome idea, and work wonderfully), but those aren't currently available as a stand-alone item, so we'd either need to hold our water for a kit, or improvise if you're looking to light this beauty quick.

In my world - Modularton - I try to light based on keeping things "playable."  My co-builder still counts her years in single digits, so I know - all threats and promises aside - she's going to split up floors when she's trying to squeeze Friends girls into LEGO chairs.

To that end, I just illuminate the ground floors. Easy to tack wires, but yes, at night the upper floor(s) are darker than I'd prefer. 

Water - ah, the challenge (and my current project).  My vision - still mostly on paper - is to see if I can't fashion something with fiber optics - a la the fireworks in the Disney castle, and put a blue LED as its light source, and leveraging the unused "flicker" channel of the one fancy pants controller, see if a bright, subtle flicker would give me a water movement effect.  (Helps that my water is also a two-plate-high scenario, so I can sandwich the fibers in between... but more on this as it unfolds.)

David Newell Thanks for joining the forum, and thanks for your post!  I'm glad you have decided to take the plunge with Ninjago City (and bravo, also, for taking on such a challenging project as your first!).  I see you placed an order on our site this week-- thank you for that!  Hopefully the lights you ordered will get you started.

Playability is always an issue as you mention, and as Paul reiterated.  For sets like our lighting kit for the Ghostbusters Firehouse, we opted for BRANCH04 ("Y" Adapter) boards on the back of each floor (stuck on with sticky squares):

 This approach provides a semi-quick connect solution, though it's not as elegant as magnets would be.  The magnetic switch you referred to is only for switching power on and off-- it does not transmit power itself.  We have been working on some prototypes with magnets (which would transmit power) to sit between floors of modular buildings:

 These work great, where you have the space for them (they do take up a lot of room on the inside or outside wall), and they are expensive ($22/pair) so if you have many floors, cost can escalate quickly.  We're working to get both the footprint and cost down, but today I think the best recommendation would be to position BRANCH04 boards in an inconspicuous location on each level of Ninjago City, and use this to connect a wire to the next level up.

We have purchased the City set ourselves, but have not yet had the courage to put it together. 😊  Please keep us posted with photos of your lighting project-- we're most likely going to work on a kit for this set, so it would be great to get the benefit of your experience.

Also, please let us know if you have any questions about the lights you just ordered.  There are a lot of great articles on this forum about building lighting, but something like Ninjago City poses a host of challenges and opportunities, so again I'm very eager to see what you come up with.  Thanks again for posting, and best of luck with your project!

Rob Klingberg Magnets?!?  I feel like I missed a memo.  😏  But very intrguing...!

I like the swivel approach, too -- avoids the challenge of reversed polarity and rigid application.

And selfishly, this would be a HUGE boost to powering the monster stadium lights I have on that build: right now it's a trio of 24-inch wires that mean nothing moves if Dad's not home to move it. 

Hmmm...  but love it!

David Newell Thank you for your efforts to document your process-- I know others here on the forum will appreciate it.  There seem to be so many options for lighting the City-- I'm excited to see what you come up with.

RE: the color-changing lights, yes this is something we are looking to sell separately soon.  If you had thoughts about how a color-changing display could work at the top of the City, please let me know-- it would be quick and easy to make a custom string for you, and we could make just about any color-changing effect you thought would look good in the City.

David Newell Hi David, thanks for posting the video of the lights-- I agree, they look great!

RE: running wires through bricks, that normally shouldn't be an issue-- the wires are definitely thin enough to be squeezed.  It sounds like you broke one though-- just let me know what you need replaced, and I'll send it.

RE: using rubber cement to place lights, this would probably work, though I'd be a little wary of putting something flammable close to electrical things.  Here's another suggestion:

https://www.amazon.com/Glue-Dots-Contains-Adhesive-32794-300/dp/B000WWK5L0

Make sure you get the 5mm size-- these will work well.

Another option for holding Pico LEDs in position (if you have sufficient space) is to use clear "boat stud" LEGO pieces in the trans-clear color.  These require a 2x2 flat space in order to mount.

As for mounting controllers, we like using sticky squares or Velcro dots.  

Hopefully this information is helpful-- let us know if you have any other questions, and keep posting photos of your progress with Ninjago City!

Welcome Shark Gillins , and soon - at least, my attempt at same.

My approach -- more so given I didn't spot the set, per se, in the film, is to get enough lights on and in this beauty without undue strain on wires from my little one's "playability" of it.

The lights are in-transit to complete, but my approach is...

•   Added the light effect controller in that has the one on-off flash, and the on-fade-off flash, to the tippy top.  (They glow in two different shades of red, but won't get into the "why" here unless you fancy the tale.)
• Going to place two green pico LEDs into the upper corners of the round thingy above the sushi restaurant
• Trying to go for different, adding two ultraviolet/purple pico LEDs into the sushi chef area below the circle (in part because I had two "extra" plugs on the adapter board, and unused is just silly)
• Shooting to "glow" up the four orange lanterns around the lower restaurant (where the crab BBQ bit calls home)
• Adding two cool white LED strips to the azul blue shop on the upper floor to glow that up
• Included a single warm white pico LED in the ground floor room where the robot mail/housekeeper was installed
• Added a warm white LED strip in the ground floor fish shop, and
• Added a blue pico LED under the bridge, held in place with a clear round boat stud tile/plate to add a neat glow to the waterway below

I expect the lights to arrive in the next day or two, and will get it outfitted and photos added.  

Certainly not an "official" kit by any means - but as commented earlier, given the fabulous nature, size and options of this set, there's nearly infinite ways to go about it... so I'm hoping to do so without (completely) breaking the bank and to minimize the number of wires that will snake up and down and need to be disconnected during play time...   Fun!  :)

The City is lit!  And sharing how, beyond the photos/video shared on Instagram. 

My biggest struggle - and arguably not the most elegant solution - was powering the rooftops, particularly with the flickering set of a dozen or so Pico LEDs and otherwise depending on the new, smokin' awesome Vertical Power Connectors (VPC).  So I'll cover my flickrer-avoidance below as well.

Ground floor:

• Power into a 2:4 expansion adapter from the neighboring building.  The four Pico plugs are used to...
  1. One warm white Pico in the lower 'robot' room
  2. One blue Pico under the bridge's arch
  3. One orange/amber to light the rear-side (over the water)lantern, and
  4. Optionally for my city integration, power a streetlight out front
• Power out of the 2:4 expansion adapter flows into a 2-LED strip light, then
• Into a 2:1 adapter that powers...
  • A flickering lighting effect controller for the front two trans-orange lanterns
  • The power up to the middle layer via a VPC.
• The middle layer is a labyrinth of wires and connectors (photo #1), and here's where I needed to terminate this leg due to the flickering. (It's also at the end of the line from the primary power supply.)  I ended up putting a brick with four side-studs facing out to hold up the two adapter boards and light effects controller (LEC).
  • VPC runs through two 2-LED strips in the sushi restaurant, then out on a 1.5-inch wire to...
  • The LEC on a flicker pattern, connected with two 1.5-inch wires to
  • Two 2:9 Pico expansion boards (terms a 1:9 expansion adapter with micro plugs, but c'mon, there's two regular plugs there, so I call them that) 😉
  • There are five Pico lights on each board, lighting the trans-orange lanterns spread throughout this layer. (Most are orange/amber Picos, but with 13 in all, three are warm white spread around, which also mixes up the color palette nicely, I think) 

And from here, well, I wanted flicker-free upper layer-and-roof lighting, so I ran - off a second USB power supply* directly here from a 24-inch wire to...

• One VPC, via a 2:1 adapter to join the two male ends, to leapfrog up to the roofs at the top of the room above 'robot' room (is it a bedroom?).  [We've committed to having this lower level - arguably yes, the second layer - stay "fixed" due to the wires both in this room and the dining room with its three lanterns across the walkway.]
• This passes through a 2-LED strip in the Comic book store - lights the room AND eliminates the need for another 2:1 adapter to join the two male ends, which goes...
• Out to the VPC that is between the sushi restaurant and below the shop.  This then has two output legs using a 1:2 Y expansion adapter:
  • The first to the light blue shop (two 2-LED strip lights in series), and out to a single UV violet purple in that boxy room with all the trans-green-neon plates (photo #3)
  • The other leg continues up to the roof stuff (by way of the fourth and final VPC), which involves (photo #2)...
• A 2:1 regular plug expansion adapter, which powers the three other boards:
  1. Leg 1 to a 2:4 expansion adapter, which provides power to three UV violet lights (strung along the ceiling near the door) in the screened-off room, and that branches out to a dual-beacon effect LEC for the top-mounted red Pico LEDs
  2. The other leg is a 1.5-inch wire into a 1:2 PICO expansion adapter for the two green Pico LEDs hidden in the upper corners of the circle feature.
     • (I didn't love the green light bleeding through the cracks above the circle, so I Bricklink'd up two 1x4 sand green plates to put in there and plug up the gaps somewhat.)
     • The upper layer/roof wires are hidden inside the UV violet lit room, just out for the photo. This does wipe out playing in this room, but it's a small price to pay for glowing awesomeness (and it's a pretty small room).  I also built up a floor-to-ceiling white brick wall one dot from the rear windows to help reflect the UV violet light back toward the doors.

I confess I've not done the math - nor want to - to sort out what this would be as a full-on kit built, but I'm pretty darn pleased with the result (video on Instragram).  Similarly, I'd not relish the thought of having to draw it out - not only for the spaghetti wiring approach and dual-power inputs, but the set itself it a virtual maze... which I enjoy it to be A-maze-ing.  ;)

* The second power supply isn't specific to this project, rather, there's simply too much square footage with teeny wires, so the town is split in the middle and powered separately... and Ninjago happens to sit on the dividing line.

No guarantees I got it right, but if my counts and crude drawing is spot-on, then we're looking at...

LIGHTS

• 13 - orange pico LEDs
• 4 - ultraviolet pico LEDs
• 2 - green pico LEDs
• 2 - red pico LEDs
• 1 - blue pico LED
• 1 - white (warm or cool) pico LED
• 5 - (2) LED strips (cool or warm white, dealer's choice)

WIRES

• 9 - 1.5-inch wires
• 2 - 6-inch wires

ADAPTERS AND GIZMOS

• 4 - Vertical Power Connectors (VPCs)
• 3 - 1:2 expansion boards (all standard plugs)
• 3 - 1:2 expansion boards (standard:pico plugs)
• 2 - 2:4 expansion boards (standard:pico plugs)
• 2 - 2:9 expansion boards (standard:pico boards)
• 1 - flickering effects Lighting Effects Controller (LEC)
• 1 - single function LEC (using function #2: flickering)
• 1 - two beacon LEC