ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Top Posters(30 Days)
Potseal 11
Recent Posts
600 KW 120/208 3 Phase Y protection
by Yooperup. 07/24/17 12:20 PM
1913 American Electrician's Handbook
by gfretwell. 07/20/17 01:08 PM
Green House wiring
by ghost307. 07/20/17 09:10 AM
Permit Snafus...AHJs and Contractors Jump in
by HotLine1. 07/18/17 08:06 PM
New in the Gallery:
SE cable question
Popular Topics(Views)
239,362 Are you busy
174,822 Re: Forum
167,211 Need opinion
Who's Online Now
0 registered members (), 57 guests, and 3 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate This Thread
Page 1 of 2 1 2
#75237 - 02/19/07 07:43 PM Lighting Question  
kyelectric  Offline
Member
Joined: Aug 2005
Posts: 64
According to the table for lighting loads in the NEC, I have to allow 2 volt-amps per square foot for a commercial building. Doesn't volt-amp mean the same thing as Watt? If so does that mean that a 400 watt bult covers 400 square feet? If not, how do you calculate lighting? Thanks!


Work Gear for Electricians and the Trades

#75238 - 02/19/07 08:38 PM Re: Lighting Question  
HotLine1  Offline


Member
Joined: Apr 2002
Posts: 6,853
Brick, NJ USA
Use the info from the NEC IF you do not have a lighting layout. IF you have a lighting layout, you use the info from the luminaires.

John


John

#75239 - 02/19/07 09:52 PM Re: Lighting Question  
kyelectric  Offline
Member
Joined: Aug 2005
Posts: 64
Hotline1,
I guess I do not understand what you are saying. Please explain. Thanks.


#75240 - 02/19/07 11:02 PM Re: Lighting Question  
SteveFehr  Offline
Member
Joined: Mar 2005
Posts: 1,208
Chesapeake, VA
NEC wants you to multiple Volts x Amps to get VAs. For lighting, Volts and Watts are pretty much identical, but since NEC is talking VA, you don't need to worry about power factor at all, it makes your job much easier.

This thread might help: https://www.electrical-contractor.net/ubb/Forum7/HTML/000551.html


#75241 - 02/19/07 11:15 PM Re: Lighting Question  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,099
Estero,Fl,usa
That is really the calculation for the general lighting load including receptacles and it is a monimum number. Occupancy
can and usually will raise what you actually need. Lighting is really calculated by lumens per square foot and each industry has different recomendations.

[This message has been edited by gfretwell (edited 02-19-2007).]


Greg Fretwell

#75242 - 02/20/07 12:00 AM Re: Lighting Question  
ITO  Offline
Member
Joined: Nov 2006
Posts: 348
Texas
I don’t mean to be rude, and part of me would love to wax on enthusiastically about what this means and how to apply it, but if you are asking this question then I sincerely hope you are not actually doing electrical work.

Perhaps you should consider taking a code study class, it would explain this and all the basics behind it, which you really should have under your belt to be an electrical contractor in the first place.

Again this is not intended to be mean or rude, and is meant in complete sincerity.


101° Rx = + /_\

#75243 - 02/20/07 02:00 AM Re: Lighting Question  
Sixer  Offline
Member
Joined: Aug 2005
Posts: 265
Canada
This is a forum where electricians, contractors, apprentices, and others, all with different levels of experience and knowledge post here to get or give advice and pick the brains of others. Everyone has their strengths and weaknesses, and in my opinion, shouldn't be shot down for asking an honest question. Just my 2 cents.


Sixer

"Will it be cheaper if I drill the holes for you?"

#75244 - 02/20/07 03:07 AM Re: Lighting Question  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,099
Estero,Fl,usa
I agree Sixer. Lighting can be as simple or as complicated as the occupancy requires. The table in 220 can be misleading. That is not a lighting plan, it is just the minimum calculated load you can use for service computations. I'm sure we could go on for days about what light you need in various situations.


Greg Fretwell

#75245 - 02/20/07 10:46 AM Re: Lighting Question  
kyelectric  Offline
Member
Joined: Aug 2005
Posts: 64
Thank you for your responses. I have worked with electrical contractors who just placed lights all over the place and if the inspector said anything, they would move them or add more lights. But, I want to actually know how to do it right. When a commercial building calls for 2 volt-amps per square foot does that mean for example that I take the voltage of the fixture (120 volts) times the amperage (.50) which gives me 60VA. Then if I divide that by 2VA (per square foot), that gives me an area of roughly 30 square feet that this fixture will cover. This is probably way off, someone help me please! : )


#75246 - 02/20/07 11:19 AM Re: Lighting Question  
ITO  Offline
Member
Joined: Nov 2006
Posts: 348
Texas
Again this is with complete sincerity; if you are asking if VA is the same as W, then you really should be looking into a code study class instead of asking people you don’t really know on the internet to explain the difference between a load calculation and whether a 400W lamp is adequate for 400sf based on reading T220.12.

I am not shooting anyone down, but there are some fundamentals here that can not be adequately taught on a message board, and the original poster is asking questions that would be thoroughly covered in a code study class, or even a structured apprenticeship through a local union.

This is what I feel is offering the correct advice for this question.


101° Rx = + /_\

Page 1 of 2 1 2

Member Spotlight
The_Lightman
The_Lightman
Orlando, Fl, USA
Posts: 49
Joined: August 2001
Show All Member Profiles 
Featured:

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Shout Box
Powered by UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.016s Queries: 15 (0.004s) Memory: 0.8179 MB (Peak: 0.9946 MB) Zlib enabled. Server Time: 2017-07-27 14:51:20 UTC