[RE-wrenches] cable spacing in trenches

[James Rudolph]

Separation is an issue the NEC does not address clearly .However, please
make sure you allow adequate room to repair the conduit if damaged, and 12'
seems to be the magic number. I lso had no luck looking in 490.

NEC 300.4(C)(2)(e) also seems a bit relevant where it allows for conductors
of different voltage ratings in manholes "if the conductors of each system
are permanently and effectively separated from the conductors of the other
systems...", but again this may be referring to separate trenches with
different system voltage ratings entering the same manhole for tapping,
allowing access for maintenance or other uses.



On Thu, Nov 3, 2011 at 5:42 PM, Jerry Caldwell <solarcowboy at yahoo.com>wrote:

> Can anyone direct me to the NEC article that stipulates how many inches of
> separation must be between cables operating at different voltages?
>
> I have a project with PV combiner box home runs at 1,000 volts DC in the
> same trench with 12.47 kV cables.  Table 300.5 shows minimum cover
> requirements for direct burial cables, but this is the distance beneath
> grade the cables must be.  Is there anywhere in the code that calls for a
> minimum separation distance between cables at different voltages?
>
> Thanks,
> Jerry Caldwell
>
>
>
> ------------------------------
> *From:* Marco Mangelsdorf <marco at pvthawaii.com>
> *To:* 'RE-wrenches' <re-wrenches at lists.re-wrenches.org>
> *Sent:* Thursday, November 3, 2011 2:27 PM
> *Subject:* [RE-wrenches] under performing Enphase inverters
>
>   For the first time, several weeks ago, after 40-50 Enphase installs,
> we’ve come across at least two M210s that we putting out consistently lower
> outputs than their immediate neighbors.
>
> We replaced the two mods first, which made no difference.  Then, in
> consultation with Enphase, replaced the M210s.  After replacing them, the
> power output was as it should be.
>
> Now I’ve got another suspect system with several underperforming mods out
> of (36).
>
> Has anyone else had this experience?
>
> Thanks,
> marco
>
>
> _______________________________________________
> List sponsored by Home Power magazine
>
> List Address: RE-wrenches at lists.re-wrenches.org
>
> Options & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> List-Archive:
> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>
> List rules & etiquette:
> www.re-wrenches.org/etiquette.htm
>
> Check out participant bios:
> www.members.re-wrenches.org
>
>
>
>
> _______________________________________________
> List sponsored by Home Power magazine
>
> List Address: RE-wrenches at lists.re-wrenches.org
>
> Options & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> List-Archive:
> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>
> List rules & etiquette:
> www.re-wrenches.org/etiquette.htm
>
> Check out participant bios:
> www.members.re-wrenches.org
>
>
>


-- 
*James B Rudolph
NABCEP Certified PV Installer

*
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20111104/cab76f80/attachment-0003.html>