calculator for estimating LED lumens to lux needed for interior lighting

[Bob Blarney]

Hello, as I consider converting from the incandescent 12V/1156 bulb system to LEDs, it seemed a bit difficult to estimate what is needed for a given activity in a particular area.

The lumen unit is a measure of how much light a source emits, but lux is the measure of the illumination of a surface. Lux is defined as lumens per square meter, taking into account the distance and angles between the light source and the surface. For fine detailed work at my bench, I like the illumination of the bench surface at 2000 lux or more, but much less is needed for other activities. I measured this area and others around the house with an app for my Android phone (of course!) called 'Light Meter' by Borce Trajkovski, which measures the lux as well as the color temperature. It is useful to get an idea about what is comfortable illumination under various conditions.

All that said, here's an online calculator that will help you to estimate the lumens needed to illuminate a surface at a given distance. For instance, at the time of writing this from the AS dinette, there is heavy overcast outside at 3pm, the distance from the light fixture to the surface of the dinette table is about 0.83m, and the measured illumination is about 130 lux, which seems rather dim. I would like to have 500 lux on the table surface. By plugging in the desired lux of 500, and setting the sliders to 120d beam angle and distance of 0.8m, I see that ~1000 lumens are needed. So I will need three 350 lumen bulbs to reach that level of illumination. You can play around with the settings to get an idea of what may be needed.

https://www.bannerengineering.com/us...alculator.html

I hope this helps.

[WaLee]

What are you doing there ? Building watches? Just get the temperature bulbs you want and switch them out for a standard swap , if anything they will seem too bright.

[GMFL]

Originally Posted by WaLee

What are you doing there ? Building watches? Just get the temperature bulbs you want and switch them out for a standard swap , if anything they will seem too bright.

That’s my thought. Over thinking this. Just swap the bulbs and roll.

[slowmover]

Having used similar in the past, I appreciate the thread, OP.

This Silver Streak of mine has several "levels" of lighting, so to speak. As in days of yore, there's more -- and of better quality -- than the bargain-brand AS trailers.

And if anyone hasn't looked around, quite a few good threads on adding lighting to trailers. All sorts of desired results.

[Iansk]

I think this is a fairly useful tool and has its place. I get wrapped up in the lighting dilemma as well, though my issues are direction and color temp. I really don't like overhead lighting and thus prefer indirect ways of illumination. Color temperature with LEDs is my biggest gripe, it has taken me quite awhile to find true "tungsten" colored bulbs that don't have a sickly green cast. I did find them recently and they were very cheap from Amazon, something like $30 for x20 We'll see how they hold up physically, but at that price I can have plenty of spares on hand vs the $8+ bulbs (warm, green) I have a drawer of that I'm waiting to sell or trade.
For light and color values I use a light meter app for my phone, I've shot and developed loads of film using the app as a guide and I'm very impressed with the accuracy. It measures LUX not lumens but there is a conversion tool to dial those numbers in. Anyway, appreciate the heads up even if others don't.

LEDs link: https://www.amazon.com/gp/aw/d/B011E...f=yo_pop_mb_pd
App link: Pocket Light Meter by Nuwaste studios
https://itunes.apple.com/us/app/pock...381698089?mt=8

Ian

[Bob Blarney]

Overthinking? It's better than overspending by buying bulbs that are inadequate. I've read several threads where someone had spent a significant amount of money on bulbs and were unhappy with the result, either light intensity or color temperature.

But a simple replacement of bulbs in fixtures is not my only interest here. I'm thinking about making new fixtures, especially for the galley. I'd like to make fixtures that are very thin and fit under the cabinets and the range hood (especially poor lighting there). I also don't like the glare of the fixture over the dinette.

So a calculator such as this is a tool that is useful for estimating the number of LEDs that I'll need. I plan to use LED strips, that can be applied in lengths from a few inches to 5 meters in length.

[slowmover]

BB, I recognize that you're on the right track. Changes in LED don't seem to stop, which is great. First it was reliability, then it was color, now we seem close to (what I'm thinking of as) full adaptability.

It's taken a good while for me to find DOT/FMVSS direct replacements for my (18) clearance and marker lamps. Simply not available a few years ago. Now, from a supplier of mil-spec lighting, which pleases me no end (RW Speaker).

These are inset (flush mount) and must also be sealed to the body after installation. I've had no desire to change type, much less do it twice.

Same for interior. Forty or more individual lamps in more than twenty fixtures.

I'd prefer to make some measurements, and purchase replacements plus spares. Be done with it.

Haven't figured out tail-lamp assembly replacements (nor exactitude of modifications for additional exterior fixtures to do with on-road safety), but it's all connected, inside and out, to my way of thinking.

All fixtures "need" new terminations, so supplies are also part. Then storage of same plus tool update.

A calculator is just some fun along that road.

And, any excuse to avoid plumbing work by dragging out the simple is a GREAT excuse.

.

[Bob Blarney]

Originally Posted by slowmover

And, any excuse to avoid plumbing work by dragging out the simple is a GREAT excuse.

.

Amen to that! The minutiae of fitting plumbing bits & pieces is an esoteric black art that I avoid whenever possible.

[Protagonist]

Originally Posted by Bob Blarney

I'm thinking about making new fixtures, especially for the galley. I'd like to make fixtures that are very thin and fit under the cabinets and the range hood (especially poor lighting there).

That seems like an excellent application for 12vDC LED rope lights. Rope lights can be cut to the length you need and the cut ends capped to prevent moisture from entering. Rope light clips with screw mounts are readily available at places like Home Depot, and can be secured with 3M Command Adhesive strips instead of screws for places like the range hood.