<div dir="ltr">Lumens would be the amount of light emitted by a source.<div>Illuminance would be how brightly the target is lit.</div><div><br></div><div>Between the source and the target is optics.</div><div><br></div><div>Example, take two S4's with same lamp and level,</div><div>one with 50' lens, other with 19' lens,</div><div>same throw distance to a target wall.</div><div><br></div><div>Both produce the same quantity of lumens from the instrument,</div><div>but the tighter lens will produce much brighter (but smaller area) illuminance on the wall</div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Aug 12, 2019 at 8:59 AM Stephen Litterst via Stagecraft <<a href="mailto:stagecraft@theatrical.net">stagecraft@theatrical.net</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">On 8/9/19 1:50 PM, Jerry Durand via Stagecraft wrote:<br>
> Are there some rules of thumb for fixture wattage for various rooms <br>
> (shop, lounge, etc.)?  I know LEDs vary a lot in efficiency (see below) <br>
> but most common LED assemblies seem to be sold by Watts.<br>
<br>
The needs are different, depending on what each room would be used for. <br>
And the guidelines are given in illuminance, since lumens per watt <br>
differs wildly from fixture to fixture.<br>
<br>
Digging into an old textbook, I found this chart --<br>
<br>
<a href="https://books.google.com/books?id=vfcFAAAAQBAJ&pg=PA333&lpg=PA333&dq=Table+14-2+Machine+Shops+and+Assembly+areas&source=bl&ots=wIwBd3dGpO&sig=ACfU3U0SXtvnI_Rwb2TB8vKBjucEG2ssCQ&hl=en&sa=X&ved=2ahUKEwiFifvYsP3jAhUIhOAKHQUSDrcQ6AEwCnoECBIQAQ#v=onepage&q=Table%2014-2%20Machine%20Shops%20and%20Assembly%20areas&f=false" rel="noreferrer" target="_blank">https://books.google.com/books?id=vfcFAAAAQBAJ&pg=PA333&lpg=PA333&dq=Table+14-2+Machine+Shops+and+Assembly+areas&source=bl&ots=wIwBd3dGpO&sig=ACfU3U0SXtvnI_Rwb2TB8vKBjucEG2ssCQ&hl=en&sa=X&ved=2ahUKEwiFifvYsP3jAhUIhOAKHQUSDrcQ6AEwCnoECBIQAQ#v=onepage&q=Table%2014-2%20Machine%20Shops%20and%20Assembly%20areas&f=false</a><br>
<br>
If the link doesn't parse, it's from "Industrial Electricity<br>
By Michael E. Brumbach" Table 14-2, Machine Shops & Assembly Areas.<br>
<br>
Steve L<br>
<br>
<br>
<br>
-- <br>
Stephen Litterst            Technical Operations Supervisor<br>
<a href="mailto:litterst@udel.edu" target="_blank">litterst@udel.edu</a>           Mitchell Hall<br>
302/831-0601                University of Delaware<br>
<br>
<br>
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</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div>...Dan Sheehan<br>Fixer of things that break</div><div>TD Walpole (MA) Footlighters<br><br></div></div></div></div></div></div></div>