Flexible Conduit [RE-wrenches]

[Phil Undercuffler]

Mark, 

--By the way, I tried sending this message this morning, but after 
getting Michael's posting I realized it didn't go out.  If you get two 
copies tomorrow, just delete this one --

The thinking behind the metal raceways through the structure, as I've 
understood it, is to provide physical protection for the array wiring, 
to protect the proverbial remodeling homeowner armed with a sawzall from 
cutting into the array feed.  After all, how many of us have turned off 
the main breaker and started gleefully hacking into the walls, knowing 
we're "safe" from live wires?  While Harry Homeowner may think nothing 
of chopping through some random romex, the hope is that he'll think a 
bit before whacking through a conduit.  

Worse case, the metal conduit will provide a return current path 
(through the sawzall blade) to trip the GFP.

I would have a friendly discussion with your inspector, to see if he 
would accept MC Cable as meeting the intent, if not the letter of the 
law.  However, you would then need to ensure that your MC Cable fittings 
could meet the requirements of 250.97, Bonding for Over 250 Volts.

As far as the 360 rule, MC Cable is a cable assembly, or factory 
assembled system of conductors and metal sheathing, while FMC is a 
conduit.  Conduits are limited to 360 degrees of bends before passing 
through a pull point.  Cable assemblies can be formed into any number of 
pretzels (while maintaining a semblance of good workmanship, of course), 
as the conductors are integral parts of the assembly.


------------------------------------------------------------

Phil Undercuffler
Technical Services Manager
Conergy, Inc.
1730 Camino Carlos Rey Suite 103
Santa Fe NM 87507 USA
Office | 505.473.3800 x4841
Fax | 505.473.3830
www.conergy.us

------------------------------------------------------------

Mark Frye wrote:
> 
> Thanks for the response Erika,
> 
> I hope the List does not mind my using some of it's bandwidth to flesh 
> out
> an issue that I am looking at.
> 
> After sending the post, I re-visited the Code which makes it clear that 
> FMC
> must have no more 360 degree of bend.
> 
> So question answered.  But why is this?  What is the thinking behind the
> requirement?
> 
> My sense is that FMC is required to allow removal and re-installation of
> conductors.  OK, makes sense.
> 
> Why is this an issue for me?  Well, NEC 2005 allows un-disconnected PV 
> DC
> conductors to run through a building, but only if in metallic conduit.  
> OK,
> so they can be in FMC, cool, but only 360 degrees.
> 
> Well Gee, MC can be bent as much as you like, no limit there under the 
> Code.
> So in some difficult retrofits where even running FMC is prohibitive,
> wouldn't it be great to use MC.
> 
> Of course the recommendation for the NEC 2008 add MC as an allowable 
> method,
> but it will be more than 6 years before my jurisdiction adopts that.
> 
> But in the end, what is the difference between fishing MC around 
> compared to
> pre-loading conductors into FMC and fishing that around.
> 
> Just trying to learn a little something and maybe make my job a little
> easier.
> 
> MPF
> 


- - - -
Hosted by Home Power magazine

To send a message: RE-wrenches at topica.com

Archive of previous messages: http://lists.topica.com/lists/RE-wrenches/read

List rules & how to change your email address: www.mrsharkey.com/wrenches/etiquette.php

Check out participant bios: www.mrsharkey.com/wrenches/

Moderator: michael.welch at homepower.com
--^----------------------------------------------------------------
This email was sent to: michael_welch at sbcglobal.net

EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9.bWljaGFl
Or send an email to: RE-wrenches-unsubscribe at topica.com

For Topica's complete suite of email marketing solutions visit:
http://www.topica.com/?p=TEXFOOTER
--^----------------------------------------------------------------