Drake;
I had trouble finding that reference, then I found it in the back in
Annex B. I think that would apply to the ampacity of the DC line, but
then for the 12.47 Kv line, I believe you would need Figure 310.60 which
then references Tables 310.60 C (77) thru Table 310.60 c (86)
Without knowing more details, it looks like Jerry would need 24" spacing
(see details 6,8, or 10).
This seems like an issue that you'd want a PE to double check and sign
off on, as that is a fairly high AC voltage, and there could possibly be
a significant induced AC voltage on the DC line (especially if its a
long shared ditch).
Ray Walters
On 11/6/2011 8:36 AM, Drake wrote:
Check out Figure Figure B.310.15(B)(2)(1)
At 07:43 AM 11/4/2011, you wrote:
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 <solarcow...@yahoo.com
<mailto:solarcow...@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 <ma...@pvthawaii.com
<mailto:ma...@pvthawaii.com>>
To: 'RE-wrenches' <re-wrenches@lists.re-wrenches.org
<mailto:re-wrenches@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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Drake Chamberlin
ATHENS ELECTRIC LLC
OH License 44810
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