[RE-wrenches] cable spacing in trenches

Jerry Caldwell solarcowboy at yahoo.com
Thu Nov 3 14:42:06 PDT 2011


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
 
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