[RE-wrenches] MC Cable for DC runs

Howie Michaelson howie at suncatchervt.com
Mon Oct 21 12:35:32 PDT 2013


Hi Bill,

The wire and cable marking guide that Dan Brown directed me to makes clear
reference to DC vs. AC listings.  I'm having trouble deciphering the
meaning of the various references, but it does list out DC temp rating
(p.18 #23) and Voltage rating (p.19 #28).

Thanks,
Howie
-- 
Howie Michaelson
NABCEP Certified Solar PV Installer™

Catamount Solar, LLC
Renewable Energy Systems Sales and Service
VT Solar Electric & Hot Water Incentive Partner
http://www.CatamountSolar.com
802-272-0004


On Mon, October 21, 2013 3:16 pm, Bill Brooks wrote:
> Howie,
>
> I think your electrician friend either misheard John or John was wrong. I
> believe the truth is that AC cable (aluminum clad) would have to be listed
> for dc. The NEC is specific about the grounding capabilities of the MC. I
> am
> unaware of any specific dc or ac requirements that MC has. There is a
> possibility that MC may be sold with an aluminum sheath. I'm not sure why
> aluminum sheathing would have anything to do with how it works, but since
> AC
> cable has that concern, this may be what John is referring to.
>
> Overall--it is bad form to say that anything is not allowed without
> specific
> references regardless of the source. I have made a few false statements in
> the past and I greatly regret those mistakes. I now try to back up my
> statements with as much information as possible so that the source of the
> information is clear. Sometimes (often) I have opinions and I try to make
> it
> clear when I am stating my opinions.
>
> John has been known to make mistakes. Unfortunately some of his recent
> articles in IAEI journal have several mistakes which is really bad since
> AHJs read his articles carefully. Hopefully we can get new articles in
> IAEI
> journal that set the record straight.
>
> Bill.
>
> -----Original Message-----
> From: re-wrenches-bounces at lists.re-wrenches.org
> [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Howie
> Michaelson
> Sent: Monday, October 21, 2013 11:15 AM
> To: RE-wrenches
> Subject: [RE-wrenches] MC Cable for DC runs
>
> Hi All,
>
> Just had a conversation with an electrician friend who took a John Wiles
> course for inspectors a couple of weeks ago, and he thought (but wasn't
> sure) that John said in order for it to be code to use MC cable for PV
> homeruns inside the building envelope, the cable needed to be rated for
> DC.
> This was new information to me, particularly since I've never heard of MC
> cable being rated specifically for DC.  Is this accurate information, and
> does anyone know what the wire spec would be for this?
>
> Thanks,
> Howie
> --
> Howie Michaelson
> NABCEP Certified Solar PV InstallerT
>
> Catamount Solar, LLC
> Renewable Energy Systems Sales and Service VT Solar Electric & Hot Water
> Incentive Partner http://www.CatamountSolar.com
> 802-272-0004
>
>
>
>






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