routing multiple cables on one overhead messenger line

Reply

  #1  
Old 12-09-11, 07:38 AM
Member
Thread Starter
Join Date: Dec 2011
Location: Canada
Posts: 2
routing multiple cables on one overhead messenger line

Hi,

I've looked all over for an answer to my question but haven't found anything in the archives. Apologies in advance if I just wasn't using the right keywords.

My issue is that I have a garage that is already wired (by an overhead messenger wire configuration), but there are two problems:
-overhead wire is 50' of #14/2, which isn't enough for the power tools I want to run (20 amp @ 120V)
-that wire is connected to the downstairs suite's electrical system, not mine!

I already have a #10/2 wire running from *my* breaker box to the outside of the house, so I just need help with the outdoor portion.

My first plan was just to buy 50' of outdoor #10/2 wire and zip tie it to the existing messenger line/wire that's out there. However, I've been told that you need to keep wires from two circuits apart to avoid inductance problems. Is this the case? Do I actually need to run another messenger wire that's 6" or so away from the existing one?

Thanks in advance!
E
 
Sponsored Links
  #2  
Old 12-09-11, 07:50 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 33,063
Following is based on US code but CEC is usually very similar to NEC.

You can only have one source of power to a detached structure so if you ran the # 10 you would have to abandon the #14. 120v general purpose power and lighting circuits can not be protected by a breaker larger then 20 amp so the most you could put the #10 on is a 20a breaker.

I would suggest Canadian equivalent of 10-3 UF-b sunlight resistant from a 30a 240 volt breaker in the breaker box and at least a 60a 6 slot subpanel in the out garage. Note if the messenger is metal it needs to be grounded to the subpanel. The subpanel will need a ground bar added, neutral bar isolated, and you will need a ground rod for it.
 

Last edited by ray2047; 12-09-11 at 08:09 AM.
  #3  
Old 12-10-11, 10:05 AM
Member
Thread Starter
Join Date: Dec 2011
Location: Canada
Posts: 2
Thanks for your excellent reply.. Just curious, code issues aside, is there an inductance (or other?) problem with running wires (on separate circuits) on the same messenger wire?

E
 
  #4  
Old 12-10-11, 10:49 AM
Member
Join Date: Feb 2006
Location: USA
Posts: 6,447
Wire

What is a messenger wire?
 
  #5  
Old 12-10-11, 11:09 AM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 12,287
Originally Posted by Wirepuller38 View Post
What is a messenger wire?
"A messenger wire is a wire or cable that is used solely for the physical support of another element, typically a conductive wire or bundle of wires."

Commonly found in overhead triplex or quadplex where the neutral conductor is a bare messenger wire

info found here

To the OP: you may only have one circuit running to your detached building. This can be a multiwire circuit.
 
  #6  
Old 12-10-11, 11:52 AM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,399
There may be a legal way to have multiple circuits to this garage apart from a MWBC. I don't know Canadian code but in the US IF this garage was multiple occupancy as is the residential part, then each stall of the garage could have it's own circuit fed from the appropriate residential panel. Doing so would likely require special dispensation from the building/electrical inspector but with the multi-tenant occupancy should not be a problem.

On the other hand, if it is a single garage occupied by only a single tenant then the normal rule would apply.
 
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