Designing Whole house LED night lights.

 

The recent discussion about LED lighting included a couple comments on the
appropriateness of LEDS for night lights. I thought it was an idea worthy of
it's own thread.

My off grid home is in the stage of construction where the interior walls
are still open accessible to add wiring runs. So, now is an opportune time
for me to add wiring to the whole house. So far, I have not installed any
low voltage wiring runs, just the 115vac wring typical of a standard US
home.

I have been casually thinking about adding a dedicated low voltage DC
circuit to support some LED night lights as a simple aid to night
navigation. I have a few ideas, but have not made any decisions yet. Maybe I
can get some ideas here to influence me in one direction or another.

I'm interested in ideas on how I might set up LED night lights throughout
the house.
Right now, I use a few glass enclosed tea candles for night lights which is
romantic, but a little too 19th century. I want something that looks
professional, and not homemade.

My inverter runs in sleep mode at night, so I'd prefer a solution that does
not require 115vac except perhaps for periodic (and hopefully infrequent)
manual battery recharging.

I wonder if it would make sense to power the LED night lights from my main
48v  battery bank, or to use  a separate dedicated bank, and maybe at a
different voltage?

My main bank runs at 48v. I suppose it would be easy enough to run a
dedicated, fused, 48v wiring run..With a 48v run, I would not have as much
voltage drop across the wire and could use smaller gauge wire. But, would I
be just burning it off in resistors required to drop the voltage to that
required by the LEDs?

Alternatively, I could setup a separate 6v (or 12v) deep cycle golf cart
battery. This would require periodic recharging, probably with an
inexpensive automotive charger plugged into my 110vac. I'd almost prefer not
to go this route, because it adds one more thing separate subsystem to have
to monitor and maintain. On the other hand, if it were 12v, then I might
find it useful for other non-nightlight applications such as recharging my
cell phone where 12v is the more common voltage. DC to DC converters are
somewhat pricey, but I suppose for one or two low draw outlets it is a
possibility.

I am thinking that a single switch per floor would be adequate for my place.
I wonder if I could just use a normal 110vac light switch for 48VDC, or I
would need a DC rated switch?

It would be nice if I could use some small gauge wire, like Cat5, or door
bell wire. Each wire run might be in the range of 100 feet per floor.

My place is 2200 square feet, on two floors. I think 6 to 8 night-lights
fixtures per floor would provide adequate  night lighting.

Is a single led per fixture adequate? Color?

Are there any off the shelf low voltage DC fixtures that might be
applicable. I don't want to reinvent the wheel if an off the shelf solution
exists, as long as it is no too expensive.

I wonder what kind of fixture could be made that would be simple to
construct, yet
not look homemade. One thought is to use a single outlet type mounting box,
and use a blank switch plate mount a led. Maybe more than one led per plate?

Ideas? Experiences? Links? Calculations?

 



Bughunter wrote:

Well if we say each LED needs 3V then 16 leds in series would use 48V.
No resistors.

Switches depend on the load. I use standard 10A ac switches for most
lights. Hell,a 10 amp ac switch running less than an amp dc is not a
problem.

Yes and white works fine or colour of your choice

All my lighting is ELV @ 12V. I rework standard light fittings to run;

LED lights, single LEDs or 18 LED lamps depending on use.

QH globes.

Dichroic Lamps.

Standard fluros with dedicated inverters.

All run with off the shelf fittings used in new ways.

I have used:

Rubber grommets as led bezels.

Here we have a fitting which allows you to drop a lamp from a ceiling
fitting. Magic, I just fit resistor and led into this and screw it into
the fixture.

PVC pipe to make lamps.

The tops of spray paint cans as reflectors for QH bulbs. Use flat white
paint for your reflectors, better than gloss white or silver.

You should get a fittings catalogue from electrical wholesale supplier
to the trade.

While you have the framing exposed is the best time to do your lighting.

I put up all my lighting at that stage. Some I moved 2 or 3 times to get
them in the right spot. I used a lot of lights. I have 15 in the kitchen
/dining alone. A mixture of QH, Dichroic and LED. They are placed for
best effect over work spaces.

The standard is a 60 or 100 watt lamp in the middle of a room. Dead loss.

Non of my lamps exceeds 20(Fluros) watts and most are either 5W(QH) or
10W(QH and Dichroic) And three, 18 LED lamps over the breakfast bar.

 



But, I don't think I'd need 16 LEDs for a single night-light. I'm thinking
that 1-3 might be
enough (light-wise) for each fixture. I don't think that I want to run
series strings in the walls although it would be possible. It feels a little
like those series strings of xmas lights, where you had to search for the
bad bulb to fix a string. With the long life of LEDs, it would much less of
a problem. Maybe it does make more sense to just use 16 leds and get more
light rather than just disipating the power in resistors as heat.


I was also thinking that a standard 10A ac switch would do the job.
I doubt that arcing would be a problem.


Not a bad idea. I'd consider it.



I am mainly focused here on night lights, meaning a few low intensity lights
spaced to aid in
navigtation. For my more general lighting needs, I use 115v compact
flourecents, and standard 115vac fixtures.



Agreed. I use no incandecents at all. Typically, I will have no more than 3
CFL's on at a time.



I am planning on a breakfast bar. Several nice looking recessed fixtures
would be cool. That might be a good candidate for some multiple white led
lights instead of CFL's.

 



Bughunter wrote:

Well I wouldn't do it, but it is a consideration if it might suit the
needs.

Then again, for a whole house night light, one at each end of a hall,
top and bottom of stairs...

The best thing is to try your lights while you can still move them
around. I had lights in a bare frame for months. I would go and try them
at night, walk around, sit in a chair to read, whatever. Moved some of
the lights several times to get the right spot for the fixture.

Tried different types of lights in a number of places to see what worked
or in a number of cases what didn't before running the cable.

 


Well, George would say that, but as always he'd be wrong.  Never drive
an LED without some kind of current limiting.