LED Bulbs

Lumens!

Forget the watts.

Are you putting in lighting to consume watts or to provide light? Which one should be your primary objective, and which one secondary?

Like Lyn said: Lumens. Get the lumens first and then figure the watts you'll need to get those lumens.

Colour temp is also a concern. What sort of space is it? Residential? Warmer colours might be in order especially in hallways and bedrooms as light with high blue content tends to keep people awake at night when they should be getting sleepy. Kitchen lights, on the other hand, might have a bluer content (or not, as it affects the appearance of food, making it less appetising) as people often have breakfast and morning coffee in the kitchen as they're trying to wake up. Workplaces may also have a bluer content, especially in meeting rooms. You know, to keep people awake. Losing battle but you do what you can.

<...keep two circuits for the light point - just in case one MCB trips for light...>

One may do whatever one wants provided the outcome is compliant with local wiring regulations; in the UK British Standard 7671 is applicable.

UK domestic lighting circuits are fed typically from a 6A breaker, corresponding to a power of around 1380W or a maximum of 23 x 60W light bulbs.

<...just in case one MCB trips...>

The only reason for the breaker to trip is a circuit load in excess of this, and a need to protect the downstream wiring therefrom. However, a continuous residential lighting load in excess of 23 x 60W light bulbs represents an uneconomic way of using electricity and retro-fitting LED lamps to the same lumens at much lower wattage would be a very attractive proposition. One would not alter the wiring or the upstream breaker protecting it while carrying out this task, so that the installation remains resilient to the prospect of 60W light bulbs being substituted for any or all of the LED replacements.

A two-storey dwelling up to, say, 4 bedrooms would typically have only one lighting circuit installed; <...two circuits for the light...> is normally unnecessary unless the dwelling were in excess of this. Were it to be necessary, it is usual to arrange the circuits in floors for practicality as the wiring for any floor would be installed in the space above the ceiling and below any floor above.

The prospect does not arise in single-storey dwellings as the circuits would be fed downstream of the metering arrangements for each dwelling within the building and a separate lighting circuit for each dwelling would be the case.

If in doubt, consult a qualified local Electrician.

Ok, one circuit for the lighting should be sufficient in case LED bulbs are used.

But in the conversion from Halogen to LED I find that replacing 1 Halogen with 2 LED bulbs is worthwhile. This is due to the fact that LED bulbs include some electronics to drive the LEDs. And the failure rate for the capacitors and other electronics is higher than the failure rate of LEDs itself. So if you do not want to end up in the dark use 2 LED bulbs because the failure possibility of two LED bulbs at the same time is rather low.

Regarding the replacement of 25W Halogen bulbs - in my case 4.5W LED bulbs of the same design (glas G10 model) were sufficient to get exactly the same measured Lumen (or LUX) on the floor or on the surface of the Kitchen cupboards. So the energy bill is 125W with Halogen vs. 22.5W with LEDs - my pocket likes that! And my wife noticed nothing as she was not at home when I changed the bulbs and did the measurements. Four weeks later she came up with the question: "Should we not change the bulbs..?

<...one circuit for the lighting should be sufficient in case LED bulbs are used...>

Well, that depends upon the size of the particular dwelling, as suggested in #4⇑.

And it also depends on your local electrical code(s). There is a always a limit as to how many "fixtures/plugs" can be included in one circuit.

The original poster's location is currently unspecified, so the regulations there may well be different to the familiar UK ones.

it is similar to uk ones.

Regards,

As long as you follow the applicable one(s).

I like LED bulbs for many things, but there are situations where standard old incandescent bulbs are better suited. Bedroom lighting is an example; studies have shown that the bright blue peak emitted by LED bulbs interferes with normal human sleep patterns. (LED bulbs use a blue LED to excite a yellow phosphor; the net result is white light. The blue peak is there, even for 'warm white' LED bulbs.) Likewise, the lighting in the 'master bath' should include some incandescent lighting for the same reason.

In terms of electrical load, it's best to assume there will be 60 watt incandescent lamps used on all circuits. But as others have pointed out, for most residential lighting - kitchens, guest bathrooms, living rooms, dens, closets, etc. - in actual use LED lamps are the most energy efficient and long-lasting, so use LEDs.

Bedroom lighting is an example; studies have shown that the bright blue peak emitted by LED bulbs interferes with normal human sleep patterns.

Uhhhhh.....you are sleeping with the light on in the bedroom. Perhaps you should try turning the light off.

I think the study you are referring to was the effect of LED street lights and LED outdoor residential lighting that is on at night and enters the bedroom through the windows.

<...the effect of LED street lights...>

Ahah! Those will definitely be on a different circuit.

GA!

But then I know people who sleep at night with a fairly large Flat screen TV turned on at normal volume most of the night or all night.

Not me! I need cool, dark, AND quiet to sleep!

Yes - cool, dark, quiet - me too. The new neighbors across the street placed very bright LED lamps in their outside fixtures and leave them on all night. Lights up my bedroom up significantly. Now I'm having sleeping problems, awakening about 2 hours into the snooze, but wonder how much is the blue portion of the LED light, or since I knew of this study about LED lighting before, how much is my mind generating the problem.

Strangely, I can fall asleep with the TV on in the living room while in my recliner, but I awaken when something important happens. It is most always a sporting event and I detect the increased crowd noise and awaken - probably a residual effect from years of well logging and waiting for the drill rig to be done while sleeping in my car - I became trained to awaken on the final blow down. Thirty years ago I could fall asleep in the daylight, in mid summer, sitting 30 feet from an operating triple drill rig, but that was then. Of course, that was not very restful sleep.

Haha. No, you knucklehead.

The blue light effect occurs in the evening hours, interfering with the brain's normal diurnal response to light. The brain expects blue light (blue sky) in the daytime. When the brain experiences blue light in the evening it interrupts the natural diurnal response of the brain, and in turn this affects sleep cycles.

Watching TV in the evening (i.e., LED LCD TVs) or reading in the evening using LED light bulbs can affect a person's sleep. Note the qualifying phrase 'can affect'. For some people the effect can be pronounced; for others there may be no effect at all.

The corollary to this is for people who suffer with SAD (seasonal affective disorder) in the wintertime. They are advised to sit in a room with bluish lighting during normal daytime hours.