Yes but...

17 amps at 12 volts is only 1.7 amps on the 120 volt side.

Thank God, I don't have to

Thank God, I don't have to jettison yet another brilliant plan on my part.

V*A=W

Volts X Amps = Watts

So... 12v x17a =204 watts

202 watts divided by 120 volts = 1.7 Amps.

Yes, but what is 1.7 amps in

Yes, but what is 1.7 amps in metric....lol?

I'm from Canada...

that is metric! 

If in europe...

Efficiency Loss

Keep in mind the 12v power supplies are not 100% efficient. The mains current will be slightly higher than 1.7A.

I use what appears to be the same LEDs - 5050 SMD 300/5M. My strips draw 3.6A each.

True

But it's not 17 amps

Shouldn't it be 1.7 ampere,

Shouldn't it be 1.7 ampere, honouring our french heritage here.

Slippery decimal!

The brain-e-acts Corps of Engineers was supposed to let out 1 million gallons of water from Lake Lanier (in Georgia) - that's 1,000,000.00.  They slipped a decimal and let out 1 BILLION gallons of water instead which lowered the lake level 7 feet in one day.  Combined with the drought that year the lake level was so low that I (and thousands others) couldn't put their boats in the lake because all of the floating docks were on dry land and all of the lake was below the ramps!  Thank you Corps of Idiots - I mean "engineers"!

1Amp/metre on 12V Secondary side = about right

Dear RSN,

"1 Amp per metre" of 3528 LED strip (150 LED elements per metre) sounds about right. I recently picked up 5metres of Warm White to light my current layout project, which matches those figures. 

In my case, given that:

- There are 2 modules
- each module is 1.2m (4') long
- I ran 2x 1.2m strips per module.

each module is running the equivalent of 2.5m (a bit over 8') of LED strip,

with a calc'd amp draw of 2.5Amps per module,

and each module's lighting is powered with a simple 12V 3A AUD$21 plugpack PSU
(via an AUD$3 inline dimmer unit).

As mentioned, that "1Amp per metre" value is on the Secondary 12V side of the equation.

In my case here in Aust, with 240VAC Primary mains,
the equivalent draw on the actual mains supply (the bit you pay your power bills for using) is 0.05Amp/metre.
(assuming a Unity phase relationship and minimal losses. The basic maths is close-enough for Model RRing).

Now, even though the "big Amp draw" values are on the "Low Voltage" side, they are still Big Amp Values!
As such, if you are powering an entire 5m strip from a single 5A-output capable PSU,

(as opposed to breaking up the 5m strips into sections,
and powering each section with a seperate smaller PSU as I am doing),

then the cable between the PSU and the LED strip must be chosen with suitable amp current rating. failure to do this will cause a lower-rated cable to get hot, and in extreme cases, (or in a short-circuit condition), could become a reasonably effective welding tool...

It's very similar to the maths and allowances one has to do if powering a DCC layout from one monster booster,
(where the cable between the booster and layout has to handle _all_ of the current drawn),

or from many smaller distributed boosters,
(where each smaller booster only needs to provide a portion of the total power required, and thus can be connected with lower-current-capacity wiring...)

Happy Modelling,
Aim to Improve,
Prof Klyzlr

Current sounds right but price seems high

Most 5 meter strips of 300 count 5050 LEDs are rated around 72 Watts or about 7 [A]mpere. One warning - the electrical traces on the strips are barely rated for this current. Therefore these strips should not be run in series. Cost wise $15 a meter sounds high. Several US suppliers such as LEDWholesalers.com has 300 count 5 meter strips of 5050 LEDs for $42 or about $8.40 per meter.

The cost per meter may be

The cost per meter may be better but I don't have an opportunity to see the light and determine whether I like it or not.  And if one goes down for whatever reason, I don't get to see the light of the replacement.  To know what I"m getting is worth the extra price for me.

I have a buddy who got them cheaper than what you quoted but was holding his breath worried the light colour might be off, he was lucky and got what he wanted, except for the light dots that reflected on his track, which he didn't want.

Example for RSN

Dear RSN,

A couple of example pics of my current LED install

Note the LED strips (you can _just_ make out the dbl row of LEDs), angled @ 45 degrees down from the valence. I did initially think I would need diffuser paper to stop "LED hotspot" effects, but with that many 120-degree beam-angle LEDs in density, the overall illumination is nice and consistent accross the scene...

...and approximately what the scene looks like from "typical viewing angle"

Happy Modelling,
Aim to Improve,
Prof Klyzlr

PS Ken, SatisLED has 3528 150LEDs/m 5m LED warm white strips for US$15 _complete_, (IE US$3 per metre).
http://www.satisled.com/smd-3528-flexible-led-strip-light-5-meter-600led-nonwaterproof_p298.html

Can use some more advice

Below is my track plan on my first deck, its not totally accurate as I drew this up for an electrical question (reversing loop) but its accurate enough for this question.  By the way, I love your coved backdrop - wonderful, and I noticed your LED's are at the front.  In the plan below you see a large reversing loop area, roughly 40 inches across.  I am planning on running whatever, but probably LED's now for heat and energy reasons, but how would you light the ballooning area in this diagram.  

I had thought I could get away with two strips, now I'm wondering if I need three.  Was going to put one strip at the front and one strip down the middle - opinions sought:[Just in the wide area, not the narrower benchwork]

LED Strips on Curves

You will probably need a strips or two to light the center of the peninsula. It can be difficult to get LED strips to conform to curves as they are very stiff in the plane of the strip. I try to avoid mounting them around curves, but when necessary I usually end up with kinks between short straight sections. Not pretty but it works.

Also power requirements were discussed, but without suggestions. Using a single OEM 12 VDC will cost less than attempting to use several smaller supplies. Although they are available from other sources, ebay can be your friend when looking for 12 Volt supplies capable of suppling the 17 Amps you felt you may need. For example:  http://12V 20A 240W Switch Switching Power Supply Driver For LED Strip Light 110V/220V. This 20 Amp supply will give you a little overhead capability. If you end up needing more power 30 Amp supplies are available for a few more dollars.

Turns out I don't need 17

Turns out I don't need 17 amps as I wasn't making the calculation in volts and this is a good thing.

LED Installation

An LED and power supply installation example complete with power calculations:

http://www.lkorailroad.com/lighting-system-operational/ 

An index of all the posts related to my layout lighting system:

http://www.lkorailroad.com/category/layout-lighting/

Most can be cut

LED strips on curves

Dear MRHers,

Please recheck the pics posted earlier, that front fascia is curved to a radii of slightly-under 5' (1500mm),
(No, the curving is not a camera lense/"fisheye"/perspective issue, it's actually a 45-deg curved foamcore module),

and the LED strips (2 parallel strips) handled the mounting without any need for seperating or jumpering
(although yes, they have built-in break-points every 3 LEDs, and can be jumpered if required)

Happy Modelling,
Aim to Improve,
Prof Klyzlr

LED strips on a 12" radius curve

Curved bit answered but not down the middle

If you go back to my wonderful schematic of track (page 2) and benchwork with a reversing loop area, do I need a strip down the center of the widest area as well?

Short strip

my approch

I have about a 110' of benchwork to light and I am running a lighting power buss of 12ga wire inside the backdrop with plugs at every section.  The led strips will be running front to back instead of along with the tracks.  Each "section" will be removable and have a plug that connects to the buss.  It is more work, but my fascia is all curves and this will eliminate any long runs of strip lights so I will not have to worry about voltage drop.  It will be powered through one BIG power supply and controlled through an Arduino (one day) for day to night changes.

John