Recessed Lighting Question

[Jimmy7]

I have a customer who would like to install 4" Led Wafer lights for general lighting in their den. The dimensions of the room are 21' x 13' with a 8' ceiling. The spec sheet for the 4" lights states it has 550 nominal lumens and 659 delivered lumens. In any case, I was wondering if there is a rule of thumb, or formula I could use in order to determine the quantity of lights needed for this space? I was thinking of using two rows of three, but I'm not sure if that would be enough light. I didn't know if I should be if I'd be better off with two rows of four.

 

[LarryFine]

With that size ratio, I'd go with a 2 x 3 pattern, plus any specific areas that need more, like a mantel or bookcase.

I would use smaller lights for specific areas, so it looks like they're not part of the main light group "on purpose."

I do that in kitchens; I use two smaller lights over the sink instead of one larger one, which also reduces shadows.

I suggest brighter lights and dimming if you need more brightness. Any more than six lights will look too "busy."

You can experiment by connecting a light to an extension cord and holding it against the ceiling in a dark room.

 

[infinity]

I have a customer who would like to install 4" Led Wafer lights for general lighting in their den. The dimensions of the room are 21' x 13' with a 8' ceiling. The spec sheet for the 4" lights states it has 550 nominal lumens and 659 delivered lumens. In any case, I was wondering if there is a rule of thumb, or formula I could use in order to determine the quantity of lights needed for this space? I was thinking of using two rows of three, but I'm not sure if that would be enough light. I didn't know if I should be if I'd be better off with two rows of four.

It really depends on how much light the customer is expecting. If they want the room really bright then 6 lights isn't enough. For example my 20' X 20' family room with a 9' 6" ceiling has 16-4" wafer lights (4 rows of 4) on a dimmer. It's not overly bright even at 100% but it is very well lit. The 14' X 22' gym has 12-6" wafer lights (3 rows of 4) and is about the same size as your room. With a dark rubber floor it's bright but not too bright. When the floor went from a light colored carpet to black rubber I had to add an extra row because it was too dark.

I would opt for more lights and do as Larry suggested put them on a dimmer. Nice thing about wafer's is that they use very little energy and you can put a million of them on a circuit.

 

[James L]

I think 6 panels at 550 lumens might leave you thirsty for more light. That's only 3300 lumens total.

4-inch lights can be (should be?) spaced about 5 feet apart. That would be 2 rows of 4 and the first would be about 3 feet from each end.

I installed 6 of them in a 13x17 living room recently and it's nice without being overly bright. But each one was 650 lumens. That was 3900 lumens in a smaller room

At a minimum, I would opt for brighter lights if using only 6

 

[acin]

Color is a factor 2700 in BR & LR 3000 in kitchen and baths is what i find most people like

 

[LarryFine]

A quick look shows that HD has 6" wafers with 900 or more lumens, and 4" ones with 700 or more.

I personally prefer fewer 6" over more 4" for most rooms, especially with table and/or floor lamps.

 

[ritelec]

A couple lamps. Done.
Really come to dislike the look of down lights.

 

[infinity]

Color is a factor 2700 in BR & LR 3000 in kitchen and baths is what i find most people like

Good point about the color. I always install the wafers that you can select the color after you have them installed in the room. Halo makes them with 5 setting that can go from 2700K to 5000K. They also make a 3000, 4000, and 5000K version for less money.

 

[LarryFine]

Halo makes them with 5 setting that can go from 2700K to 5000K. They also make a 3000, 4000, and 5000K version for less money.

I've read that the best LED life is obtained at the middle setting, because the lights contain only the warmest and coolest chip colors, and make the others by proportionally mixing them. The middle setting will illuminate the two colors equally (50-50); the extreme end colors only drive one set of chips to 100%.

 

[Kansas Mountain]

Give your supply house the basic dimensions of the space (or drawings if available) and tell them what fc levels you want at floor or counter height, and what color temps. They should either be able to whip up some quick calculations for you with dimensioned spacing, or have one of the local lighting reps do it. This should be provided as a free service for the opportunity to sell you the lights.

 

[infinity]

Give your supply house the basic dimensions of the space (or drawings if available) and tell them what fc levels you want at floor or counter height, and what color temps. They should either be able to whip up some quick calculations for you with dimensioned spacing, or have one of the local lighting reps do it. This should be provided as a free service for the opportunity to sell you the lights.

The question is then how many foot candles does the customer want? I would guess that many of them have no idea how many they want. It's there a general rule of thumb?

 

[James L]

I've read that the best LED life is obtained at the middle setting, because the lights contain only the warmest and coolest chip colors, and make the others by proportionally mixing them. The middle setting will illuminate the two colors equally (50-50); the extreme end colors only drive one set of chips to 100%.

The life of the LEDs is almost meaningless
At best, usually inconsequential

It's all the other electronics that fail sooner.

Whether it's the driver or the mixing on the selector switch, some other component will almost inevitably fail before any of the LEDs

 

[brantmacga]

A couple lamps. Done.
Really come to dislike the look of down lights.

I don't disagree.

I think putting up rows of recessed lights in residential isn't the best choice. I like to use them as accent lighting combined with lamps and wall sconces. Not all of my customers agree, so I still end up putting them in as usual on some jobs.

I do recommend using the smallest aperture possible, and actual recessed lighting to limit glare instead of these wafer lights or "can killers".

 

[Kansas Mountain]

The question is then how many foot candles does the customer want? I would guess that many of them have no idea how many they want. It's there a general rule of thumb?

Definitely something that can vary based on individual customer preferences, but if they don't know/care, here's the IES recommended levels for general applications.

 

[infinity]

Definitely something that can vary based on individual customer preferences, but if they don't know/care, here's the IES recommended levels for general applications

Thanks, but even with that how is the homeowner going to know that what they think that they want is going to be enough light? I always opt for too much light with a dimmer rather than not enough.