Built-in cabinet lighting - need wiring (door initiated switch) help

[Gregor]

24v is more efficient - less wasted wattage for a given system.

Could you please elaborate how you come to this conclusion?

 

[tjbnwi]

Peter , et al  - in the USA , the opposite is true.

They are very few 24v systems available here. 

LooX is available in both voltages through Hafele and the systems are very competitively priced. 

24v is more efficient - less wasted wattage for a given system.  Which is prob. why it's more popular in Europe where electricity is more expensive.

GM Lighting. Pick your voltage and output.
http://gmlighting.net

Tom

 

[Cheese]

I settled on 12v because the bulb/LED selection was so much greater. I'm powering 19 fence lights, 26 bollards, 3 spotlights and 2 step lights with just 2 very small Triad solid-state, potted transformers rated at 40 watts each.

The main line to each of the 5 junction boxes is via 12 ga wire and from each junction box to the lights 14 ga wire is used. The longest continuous run is 80 feet. All lights are on from dusk to dawn and it's been working for over 7 years.

 

[antss]

GM Lighting. Pick your voltage and output.http://gmlighting.net
Tom

^^^ 
illustrates my point exactly - there are at least two times as many 12v options from this company as there are 24v.

gregor - the voltage drop is going to cause the 12v transformer to work harder; wasting more wattage that just makes heat.    This has no real practical value for something like scorpion's cabinet which will probably have less than 10ft. / 3m of cabling.  The drop/loss won't even be measurable with equipment available to most people.

On a practical note: the 24v systems allow for use of smaller sized wire, which can be an advantage for concealing them in cabinets or shelves.  Especially if you're drilling a hole in a 19mm thick board.

 

[Gregor]

Gregor - the voltage drop is going to cause the 12v transformer to work harder; wasting more wattage that just makes heat.    This has no real practical value for something like scorpion's cabinet which will probably have less than 10ft. / 3m of cabling.  The drop/loss won't even be measurable with equipment available to most people.

The 24V is, speaking efficiency, worse than the 12V version as the resistors dropping the voltage down to the level the LED needs might create little bit more heat - but as you stated it's neglible.

On a practical note: the 24v systems allow for use of smaller sized wire, which can be an advantage for concealing them in cabinets or shelves.  Especially if you're drilling a hole in a 19mm thick board.

With LED that is also not that big of a problem anymore as 1.5mm² is fine for 10A (which would translate to 120W @12V) quite bright with LED these days, compared to classical 12V halogen filament bulbs.

IMHO the only real issue with 12V is voltage drop on long runs (30m+, when you have a central transformer and pull wires from there to the fixtures of a room) where the reduced voltage on the end of the wire might lead to the leds no longer providing the intended brightness (as a 0.5V change in line voltage might translate to a 50% change to the voltage at the input of the leds, after the resistor that is mounted infront of them). For such setups a 24V system has benefits, also when you additionally run industrial bus stuff (as this also often runs on 24V, for the same reasons) because you can then share the transformers for both lighting and the bus connectors.

 

[Cheese]

[member=44099]Cheese[/member] - those are neat and kinda where I thought I might be headed.  If they require a 3/8"-diameter hole, how deep does the hole need to be?  Based on the picture it looks like more than an inch but maybe the pic is deceiving.  I need the door side to conceal in a 3/4-inch thick door. 

I need to see how I can figure out if the 110v -> 12v power supply can handle being powered 100% of the time with no load most of it.  That's not something I remember reading in the documentation.

Hey [member=27782]Scorpion[/member] the sensors come in different lengths depending upon their manufacturer. The sensor itself shouldn't be an issue, I think your concern is centered on the magnetic actuator. The actuators can be rather lengthy, however I've found some that are only 3/8"-1/2" long. I haven't tried it, but I would think that a small, thin rare earth neodymium magnet would actuate the sensor if it is installed with the proper polarity. These magnets are typically only 1/16"-1/4" thick.

I can't imagine there will be an issue with constant power being supplied to the transformer/driver. If there's no load, no current will be drawn.