[RE-wrenches] MC Cable for DC runs

[Bill Brooks]

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