multiwire/circuit cable

Reply

  #1  
Old 05-28-06, 03:04 PM
ddr
ddr is offline
Member
Thread Starter
Join Date: May 2006
Location: New York City
Posts: 133
multiwire/circuit cable

Hello all,

The short question:
Does anyone know if they make (or plan to make) steel jacket AC cable in a 12/2/2 configuration?

The long reason:
I would like to run multiwire 12AWG cables from the service panel to junction boxes in the the attic/crawlspaces of my house so I can run more circuits through the exiting holes. I know I could use 12/3 cable but would like to avoid any neutral overcurrent issues, electrical hum on circuits sharing a common neutral, etc.

I know they make 12/4 AC cable, but the color code is black, red, blue, and white and the NEC prohibits recoding hot colored conductors for neutral use in cables 6AWG or thinner. So what I need is a 12/2/2 configuration (black, red, white, white, (with one or both of the whites coded to indicate which hot it is the neutral for).

I know they make NM and MC cables with 12/2/2 configurations, but I live in New York City and although NM cable has now become legal for certain structures I would prefer to stick with steel jacket AC so I can avoid the need to install safety plates, required with NM cable, when I fish a new cable through an existing cable's path. Also, NM and MC have a grounding wire and I don't have enough extra spaces on the neutral/ground bar.

Thanks in advance for any help,
ddr
 

Last edited by ddr; 05-29-06 at 08:40 AM.
Sponsored Links
  #2  
Old 05-28-06, 03:19 PM
nap's Avatar
nap
nap is offline
New Member
Join Date: May 2006
Location: north
Posts: 4,163
Cruise this pdf with special attention to pgs 21 and 34.
I think this may be what you are looking for.

http://www.afcweb.com/pdfs/afc_cable...bl_cat_all.pdf
 
  #3  
Old 05-28-06, 03:39 PM
Speedy Petey's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Nov 2003
Posts: 2,455
Just so you know. In most panels you can double, and sometimes triple up grounds on the bar.

Also, as long as a multi wire is installed correctly, ie: different poles in the panel, there is NO neutral overcurrent. In fact the neutral carries less current. And in a residence hum and harmonics are really a non-issue.

I would just run 12/3 and be done with it.
Your situation can't be any different than the thousands of others who use 3-wire and multi-wires for spares.
 
  #4  
Old 05-28-06, 09:53 PM
ddr
ddr is offline
Member
Thread Starter
Join Date: May 2006
Location: New York City
Posts: 133
Thanks guys.

nap: Checked out the link; didn't see exactly what I was looking for, but e-mailed AFC (and Southwire) to see if they had any plans to market such an animal. We'll see.

Speedy Petey: Thanks for the tip re. the grounds; I'll look into it.

The whole interference/hum issue is that I have some sensitive video/computer set ups and I wanted to have them with separate neutrals, but wanted to pull less cable. I also read the following clip...

"Historically, contractors have used three conductor cables and a shared neutral for two bedroom circuits to reduce the labor costs over installing two cables," explained Dave Mercier, technical director for Southwire’s Electrical Division. "However, with the newly required AFCI breakers for bedrooms, many builders must now use separate neutrals when two circuits are needed."

...and figured it would be better to have the separate neutrals at the ready. Maybe I'm just over-thinking the whole thing, which is generally dangerous.
 
  #5  
Old 05-29-06, 04:34 AM
Speedy Petey's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Nov 2003
Posts: 2,455
This has been a common misconception since the onset of AFCIs, even by electricians.
AFCIs ARE most definitely available in two-pole versions. You CAN use them on multi-wire circuits.


Multi-wire circuits IMO are a good idea for several reasons.
For example; saving wire, labor, time, and lessening voltage drop. Even greatly reducing wire clutter in the panel and easing the wire crowding on the neutral/ground bar.

Wire a few new homes and you'll see the benefit of using them.
 
Reply

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 Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'