Will this be too bright?

[Albumen]

I'm having a room converted to a home office. It's roughly 8 feet by 16. 11.4 metres area intact, with a very low ceiling, 2.2 metres.

I'll be teaching guitar and doing a lot of computer work in it.

I originally bought to ceiling lights which take a max 60w incandescent or 11w cfl. I don't think this would be enough.

So today I bought 2 T5 fittings, each taking a pair of 28w T5s. That gives me 11600 lumens altogether.

I'm thinking now that that's going to be too much. Gives me 1000 lux.

Questions:

1. Can I run just one bulb out of a pair, or will it knacker the ballast?

2. I know there are coloured gel sleeves for T5 bulbs. But are there any neutral density ones?

3. Some places recommend 800 lux for workshops. Is light like sound, where double the measured power isn't double the perceived sound?

Thing is electrician's coming tomorrow to fit. There's other things he can do while I go and change. But if I let him fit these is it a major job to change later?

Thanks

 

[chivers67]

1. Can I run just one bulb out of a pair, or will it knacker the ballast?
Thanks

Not good in my expereince to have one out, worked in a school and some wouldn't work with only one working and if they did didn't alwayslast long.

You could always have some plug in up lighters?

 

[333rocky333]

Its more likely the fitting wont work with one tube, they usually use a twin ballast rather than two singles, you could try and use colour 830 tubes they are not as bright as the 840 which is usually supplied

 

[17thman]

would this help

http://www.lithonia.com/RT5/pdf/QTP T5 Powersense.pdf

http://www.mr-resistor.co.uk/products.aspx?g=19&t=568&r=349

 

[Albumen]

Thanks for you replies folks. Especially 17th man. Some useful ideas there. Though not sure how much can be done without destroying some of my new plaster. Should have planned this earlier.

My basic question is, does that seem like a lot of light for the room size and usage I've described? I'd rather not go down the route of dimmable ballasts if what I really need to do is just get smaller lamps now, and augment with the occasional desk lamp if required.

Many thanks.

 

[Albumen]

I see from the responses, and from my web searches, that dimming ballasts are available. But I don't understand the control circuitry.

Is it possible to retrofit a dimming system using pre-existing wiring? Or does some new wiring (the 0-10v I keep reading about) have to be installed.

Thanks.

 

[ban-all-sheds]

Is it possible to retrofit a dimming system using pre-existing wiring? Or does some new wiring (the 0-10v I keep reading about) have to be installed.

Yes, but you need a ballast which does 1-10V dimming, not 0-10V. They are completely different systems - with the former the ballast provides its own control voltage which goes to the 1-10V dimmer (MK make one - I'm sure there will be others).

With the latter you need to provide power to the dimmer and it sends the 0-10V control voltage to the ballast (or it talks to a dimmer pack using a protocol such as DMX or DALI which provides the control voltage).

See //www.diynot.com/forums/viewtopic.php?t=236100&start=0

 

[Albumen]

Thanks for your replies folks.

Electrician fitted lights. At first he, the wife and I all said - 'there, that's not too bright is it?'

Now I'm not so sure. I just tried turning one bulb in each fitting, and it was a lot nicer. Somewhere between the two would be good.

So I'm heading towards a dimmer.

I'll think out loud, tell me if I'm wrong.

1. Dimming ballasts are available for HF T5 bulbs. With luck they'll be a physical fit.

2. They usually have a control output (1-10volts) which could go to the switch. Which is a single two core wire. A dimmer switch for this would either be a straight potentiometer, or more likely an electronic version thereof.

3. But that will still leave me unable to turn the lights actually off. They'll always be at 5%. Yes?

So what's wrong with this:

1. Install the ballasts.

2. Leave the switch exactly as is.

3. Take a very short pair of wires to a dimmer. Presumably it's not carrying much current, so can be fairly thin. Ceiling mounted. Each light can be individually dimmed. And yes, the ceiling is very low, so I can reach it easily without standing on anything.

Opinions welcome.

 

[ban-all-sheds]

AFAIK you can turn dimmed lights completely off.

Plan B - replace each ballast with 2 singles, individually switched.