ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Strobing LEDs
by Bill Addiss - 10/06/22 07:33 PM
How's Florida doing with Hurricane Ian?
by Bill Addiss - 09/28/22 12:41 PM
Tough being a lineman's kid
by Bill Addiss - 09/28/22 12:39 PM
GFCI's pops in large numbers
by dsk - 09/26/22 04:35 AM
AFCI’s Revisited
by sparky - 09/24/22 09:58 AM
New in the Gallery:
240/208 to a house
240/208 to a house
by wa2ise, October 9
Now you know.
Now you know.
by Tom_Horne, September 7
Who's Online Now
0 members (), 26 guests, and 9 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
#40068 07/11/04 11:47 PM
Joined: Dec 2001
Posts: 15
C
Member
Got a lighting RFQ for a new laundromat (100ft x 28ft x10ft high). The owner thinks that 8 fixtures (2'x4' w/4 lamps) will be enough. Does anyone have a link to a site that has footcandle recomendations?

Joined: Apr 2002
Posts: 558
C
Member
I don’t have any good recommendations for sites to check but hopefully one of the other members can help you out. I will tell you that if this project was in California you would be allowed to use 2520 watts maximum to light this area (2800 x .9watts/sqft). Using the allowed watts for a given area usually gives a pretty good idea of how many fixtures will be needed. I would guess that it will take closer to 20 fixtures to light this area.

Curt


Curt Swartz
Joined: Mar 2002
Posts: 582
R
Ron Offline
Member
See the table about 3/4 of the way down the following site. http://www.holophane.com/School/HL-862.htm


Ron
Joined: Jan 2001
Posts: 1,044
Tom Offline
Member
20 fixtures looks about right for 30fc maintained.

8 fixtures will result in very uneven lighting & will get you about 18fc. Was the owner previously an owner of a movie theater? They were also notoriously stingy with light.

Tom


Few things are harder to put up with than the annoyance of a good example.
Joined: Dec 2001
Posts: 15
C
Member
Tom
How did you arrive at these numbers?

Joined: Jan 2001
Posts: 1,044
Tom Offline
Member
I've trained a spreadsheet to calculate room cavity ratios. Using a 10' ceiling height and an assumed workplane of 30" above finish floor and the other room dimensions you listed, the RCR came out at a little under 2.

Then, I pulled out a really old lighting design book (Rapid Lighting Design and Cost Estimating by Prafulla C. Sorcar, P.E. copyright 1979), looked up the 2x4 fixture curves, assumed 30 fc & read the curve over to the square footage per fixture, divided that into your square footage which worked out to 19.xxx fixtures.

As for the 18fc estimate, I did the same thing backwards by dividing the square footage by # of fixtures, read over to the curve & up to the fc.

I'm not sure how accurate this book is, but I've never had any complaints about things being too dim.

BTW, Prafulla has published other lighting books & is multi-talented, visit his site at www.manicksorcar.com



[This message has been edited by Tom (edited 07-12-2004).]


Few things are harder to put up with than the annoyance of a good example.
Joined: Aug 2001
Posts: 464
Likes: 1
J
Member
go to www.simkar.com You can download the simply indoor lighting calculation software with photometric data.

This will let you see a suggested layout with lighting values for your project. Other lighting manufacturers have photometric data for their fixtures for download that can be used with this also.

Joined: Feb 2002
Posts: 182
B
Bob Offline
Member
I ran your room size using the Hubbell
Software. For 25 footcandles you would need
2 rows of 6 fixtures.


Link Copied to Clipboard
Featured:

Tools for Electricians
Tools for Electricians
 

* * * * * * *
2023 National Electrical Code (NEC)
2023 NEC Now Available!
 
* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
Grover
Grover
Sebago, ME, USA
Posts: 109
Joined: January 2005
Top Posters(30 Days)
dsk 3
Popular Topics(Views)
297,818 Are you busy
228,536 Re: Forum
213,363 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.5