Replies

1. 
   DaveRicheson | Apr 26, 2006 12:57pm | #1

   Ever notice how the utility company uses a solid #6?

   That is generaly a ground, not a neutral. We also use #4 solid  copper and copper coated  alum. for grounds. Tuff stuff to use unless you are going straigth down a pole.

   Dave

2. 
   maddog3 | Apr 26, 2006 01:12pm | #2

   start with this........
   Neutral curren t= SQRT((Ia*Ia+Ib*Ib+Ic*Ic)-(Ia*Ib+Ib*Ic+Ic*Ia))

   if you are on a single phase feed from the utility ...
   I'm almost positive Hartmann or Stuart or DanH will come along and trash it

   you will need to know the amperage of your circuits as well

   kind of a silly request from the inspector IMO

   .

   .

   .

   'Wer ist jetzt der Idiot?'

1. 
   brownbagg | Apr 26, 2006 02:47pm | #3

   its easier just to run all four wires the same size, so there is no argument. Its hell to argue with the city after you bought the wire.

1. 
   maddog3 | Apr 26, 2006 11:58pm | #4

   yep........

   .

   .

   'Wer ist jetzt der Idiot?'

3. 
   maddog3 | Apr 27, 2006 12:09am | #5

   the formula is meant for a 3ø system where things are 120 º apart..!

   ..on your service try to balance wattages on opposing phases or just run the full size N to avoid any complications with the inspector .

   Besides, the jury still seems to be out on Harmonics from modern apliances, and the problems with smaller Neutrals

   .

   .

   .

   'Wer ist jetzt der Idiot?'

1. 
   highfigh | Apr 27, 2006 01:50am | #6

   I would imagine that the harmonics are stronger in a loaded wire of smaller gauge, just like any other circuit where they increase when there is high current and the resistance increases.
   "I cut this piece four times and it's still too short."

1. 
   maddog3 | Apr 27, 2006 02:34am | #7

   .....that is the reason commercial buildings almost always use separate circuits for homeruns to office furniture and equipment.....no more three hots and a N ......too many possible problems down the road. smaller homes most likely wouldn't see the same overloaded conditions , but better safe than sorry.

   .

   .

   'Wer ist jetzt der Idiot?'

4. 
   Stuart | Apr 27, 2006 02:49am | #8

   Article 220.61 of the 2005 NEC (it was article 220-22 in earlier editions, I believe) deals with determining the size of the neutral conductor.  You have to do some calculating based on the unbalanced and nonlinear loads.  However, I'd think that for a residential service you don't save all that much by downsizing the wire.

   You can look at the current code online (but you can't download or print it) at http://www.nfpa.org/freecodes/free_access_document.asp

5. 
   Stuart | Apr 27, 2006 06:02am | #9

   That's weird.  It's doing the same thing to me but it worked earlier.  Try this:  Go to the main page at http://www.nfpa.org/, then click on Codes and Standards > Document List and Code Cycle Information > NFPA 70, then go to the bottom of that screen and click on Preview This Document.  It brings you back to the page I posted in the first place, but this time when you click on I Agree it lets you go forward to the next window where you click on Open National Electrical Code.