AC/DC in Same Conduit? [RE-wrenches]

[Bill Brooks]

David,

The only concern I would have with a 500' run of DC and AC is the potential
for harmonic coupling of the AC with DC circuit. I've never tried it so I
can't say it would even happen, but it seems questionable at best and it
seems that it could cause the inverter to operate in a funky manner. The
other option would be to put the inverter out at the array so there is only
AC in the conduit. Would this work for you. I know the DC side is higher
voltage and would be better to run the longer distance, but this seems like
an exception to that rule.

Bill.


-----Original Message-----
From: David Blecker [mailto:blecker at earthsys.org]
Sent: Thursday, July 11, 2002 11:12 AM
To: RE-wrenches at topica.com
Subject: Re: AC/DC in Same Conduit? [RE-wrenches]


Hmmm...so the question then becomes, is there a safety or performance reason
not to mix voltages?  I assume Martha Stewart would not approve of such
things unless the conductors were color coordinated.

Or, is this an NEC conspiracy to sell more conduit?  I'm doing an PV install
in remote Alaska for an locally owned utility.  No code inspectors nor NEC
deities to frown upon our work.  Its a long run from the array to the
building (500 feet) and the thought of installing 1000 feet of conduit for
an AC and DC run doesn't make my newt within very joyful.

Thoughts?

-David

At 10:23 AM 7/11/2002 -0700, you wrote:
>Wrenches:
>
>Now that I know there are NEC Goddesses, I'll have to pay more attention!
>(Not entirely off-topic, Michael :-) )
>
>Mixing of "separately derived" power sources within a single raceway,
>without a physical separation, to my knowledge has always been prohibited.
>This includes 480 VAC in the same conduit as 120 VAC, etc.
>
>I don't have time to dig out the reference(s) right this second, but, as
>Bill B said, "Do it and become a Newt".  Do Newts still exist?  I thought
>the last one retired a couple of years ago.....
>
>-Matt Lafferty
>pvpro at attbi.com
>
>David asks:
>
>> Can 120 VAC and high voltage (about 350 V) power cables be run in the
same
>conduit without offending the NEC gods and goddesses?
>>

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