How To Calculate Box Fill - Electrical - Page 2 - DIY Chatroom Home Improvement Forum

 DIY Chatroom Home Improvement Forum how to calculate box fill
 Register Blogs Articles Rewards Search Today's Posts Mark Forums Read

01-26-2009, 08:29 PM   #16
Member

Join Date: Dec 2008
Location: Rhode Island
Posts: 171
Rewards Points: 75

Quote:
 Originally Posted by ponch37300 Wouldn't (2) 14-2 wires and (1) 14-3 be 7 wires plus one ground plus one switch times 2 for 14 gauge wire be 18 cubic inches? Guess I was wrong with 20.
7 current carrying 7x2(14ga)=14
All grounds=1
switch=2

14+1+2=17 (providing the box doesn't have internal clamps)

 01-26-2009, 08:39 PM #17 Member   Join Date: Dec 2008 Location: Rhode Island Posts: 171 Rewards Points: 75 You were right with 20cu in All grounds count as 1 conductor which counts as 2 The switch counts as 2 conductors which counts as 4 If you are using 14 ga. 7x2=14 1x2=2 2x2=4 14+2+4=20
 01-26-2009, 08:49 PM #18 Member   Join Date: Jan 2009 Location: South of Boston, MA Posts: 17,248 Rewards Points: 2,000 I always go oversize on boxes since I use 2x6 walls After trying to insert what fits under code its a good idea to go slightly larger if you acn

01-26-2009, 08:59 PM   #19
Member

Join Date: Jan 2009
Location: Boston, MA
Posts: 241
Rewards Points: 150

Quote:
 Originally Posted by ponch37300 Wouldn't (2) 14-2 wires and (1) 14-3 be 7 wires plus one ground plus one switch times 2 for 14 gauge wire be 18 cubic inches? Guess I was wrong with 20.

2 14/2 = 4 wires at 1 volume = 4 x 2.0 = 8
1 14/3 = 3 wires at 1 volume = 3 x 2.0 = 6
all grounds = 1 volume = 1 x 2.0 = 2
One switch = 2 volumes = 2 x 2.0 = 4

Total is 20 cubic inches. I am still new at this but I believe this is right.

01-27-2009, 05:58 AM   #20
Electrician

Join Date: Aug 2008
Location: Near Jackson Michigan Area
Posts: 1,452
Rewards Points: 504

Quote:
 Originally Posted by ponch37300 Wouldn't (2) 14-2 wires and (1) 14-3 be 7 wires plus one ground plus one switch times 2 for 14 gauge wire be 18 cubic inches? Guess I was wrong with 20.
I came up with 20 cu in.

Last edited by SD515; 01-27-2009 at 06:04 AM.

 01-27-2009, 10:18 AM #21 Member   Join Date: Nov 2007 Location: Appleton, Wisconsin Posts: 1,213 Rewards Points: 26 Thanks everyone. I understand it now. Guess I had it right the first time and when I went back to double check I only counted the switch as one volume. Thanks again everyone for sharing your knowledge!
 01-27-2009, 06:01 PM #22 Licensed Electrician     Join Date: Feb 2008 Location: central wisconsin Posts: 989 Rewards Points: 514 I think it's great that this thread will be found during searches and give accurate and good advice to many people in the future. __________________ John
 01-27-2009, 09:54 PM #23 Member   Join Date: Jan 2009 Location: Boston, MA Posts: 241 Rewards Points: 150 It surprises me that someone does not have a "calculator" for this. I made an excel spreadsheet which I am still testing but so far it has worked great. Just plug in numbers and you get a result. I did see some software for all types of calculations but it is a bit expensive.
 01-28-2009, 08:42 AM #24 Licensed Electrician     Join Date: Feb 2008 Location: central wisconsin Posts: 989 Rewards Points: 514 People that do it everyday barely think about it. For instance we know that a 2 gang switch box (32 CI) is ok with 2 14-3 and 2 14-2 along with 2 three way switches. That would be two 3 way circuits at the 2nd set of switches, or at the 1st set of switches with the line set continuing to another box. Or a single gang receptacle box (20.3) is ok with 3 12-2 and a receptacle outlet. And those are the most common filled up situations. Most boxes would have less wires that that in a typical circuit layout. Those are the ones which approach the fill limit. __________________ John
01-28-2009, 09:48 AM   #25
Member

Join Date: Jan 2009
Location: Boston, MA
Posts: 241
Rewards Points: 150

makes sense. The more I work with this the more "automatic" it becomes. It makes perfect sense that if you work with this on a daily basis it would just be second nature to you.

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are Off Pingbacks are Off Refbacks are Off Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post ssybert Building & Construction 5 06-12-2008 06:19 AM amakarevic Building & Construction 3 04-16-2008 09:07 PM analogmusicman Building & Construction 2 02-23-2008 07:53 PM

Top of Page | View New Posts