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#17573 - 11/29/02 06:52 PM help with lighting demand!!!  
Mike_Riverside  Offline
Joined: Aug 2002
Posts: 33
can someone please check this math...

i believe the only 3 fixtures would be required, right?

should i use 3 or 4?

will this drawing provide adequit light for the office?

any suggestions?


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#17574 - 11/29/02 07:04 PM Re: help with lighting demand!!!  
JuddsAirco  Offline
Joined: Oct 2002
Posts: 49
If this is a drop ceiling I would probably go with 4 three bulb T-8 troffers. These are more efficent than the old T-12 bulbs while providing the same amount of light. There is also a T-8 troffer on the market where one bulb will light when the power is down as an alternative to the wall pack emergency lights.

[This message has been edited by JuddsAirco (edited 11-29-2002).]

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#17575 - 11/29/02 07:30 PM Re: help with lighting demand!!!  
Mike_Riverside  Offline
Joined: Aug 2002
Posts: 33
thanks for the help, these fixtures are lithoania 4 bulb t-8 troffers.

#17576 - 11/29/02 07:48 PM Re: help with lighting demand!!!  
caselec  Offline
Joined: Apr 2002
Posts: 558
San Jose, CA
Where are you getting the 3VA/SQ FT. from?


Curt Swartz

#17577 - 11/29/02 08:26 PM Re: help with lighting demand!!!  
Mike_Riverside  Offline
Joined: Aug 2002
Posts: 33
2002 Ugly's

#17578 - 11/29/02 09:02 PM Re: help with lighting demand!!!  
caselec  Offline
Joined: Apr 2002
Posts: 558
San Jose, CA
The NEC requires a minimum of 3.5VA/SQ.FT. for lighting load calculations but this has nothing to do with the number of fixtures required to illuminate an office space. The manufacture of the fixture or lighting designer can tell you how many fixtures will be needed to provide the desired lighting level. In California you are only allowed a maximum of 1.6 watts/SQ.FT. for office space so you would only be permitted to use two 4-lamp fixtures.


Curt Swartz

#17579 - 11/30/02 02:44 AM Re: help with lighting demand!!!  
joeh20  Offline
Joined: Mar 2002
Posts: 95
Tullahoma, TN, 37388
VA's are for load calculations. Foot candles is how you measure the amount of lighting you provide or require. The NEC will address your lighting load for your service calculations, but doesn't dictate a specific amount of lighting for a particular space. Each type of occupancy differs somewhat. The requirements from the California code of 1.6 watts seems adequate for most offices.

Lighting the way

#17580 - 11/30/02 02:51 PM Re: help with lighting demand!!!  
electure  Offline

Joined: Dec 2000
Posts: 4,260
Fullerton, CA USA
I'd use the 1.6 watts per square foot method.

#17581 - 12/01/02 10:04 PM Re: help with lighting demand!!!  
Scott35  Offline

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I can't access the site!!! Keep getting 404 error [Bad Request]!!!

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#17582 - 12/02/02 10:50 AM Re: help with lighting demand!!!  
Fredmeister  Offline
Joined: Nov 2002
Posts: 23
Beacon, NY, US
The preferred solution to this:

All this room needs is one Direct/Indirect 8Ft Fixture. You could use T8 or T5.. your choice. ( 4lamps - 2 Ballasts)

T8 will give you .83 Watts/sqft - T5 will come in at 0.94 watts per sqft.

Make sure that the fixture being used has the right optics to cover the area. Most of these types will.

Regardless of any Energy Codes, this will produce a very well lit office. Tell your client to put a Task Light ( Table Lamp or Under Counter Light) where needed.
Btw.: These are excluded from the Lighting calculations because they are plugged in.

The Price for such a Fixture is about the same as 4 good Lay-in Parabolics but the indirect ones will pay for themselfes in no time flat if you consider the energy savings.


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