Looking at this older post [below] which came up as I searched "bundling:"
Take this scenario with a blocky array laid out with all the positives on the west and all the negs on the east, CB in the north: For example, 8 strings of 7: [1= the positive HR of each string; 7= the negative HR of each string] As I've drawn below, On the west array edge, you'd have all the + running north toward the CB in one bundle of only-positive wires, and the same on the east flank with all the -. ___CB___ +1234567- +1234567- +1234567- +1234567- +1234567- +1234567- +1234567- +1234567- Any reason it be better to lay out the array this way, with current flow reversed every other row?: ___CB___ +1234567- -7654321+ +1234567- -7654321+ +1234567- -7654321+ +1234567- -7654321+ Re: original thread, Is the heating irrespective of whether the bundles are mixed pos/neg, or worse if all 1 polarity? And, sorry but I could not find what William wrote about the impedance [DC resistance] in this situation. Hope my question is clear. Thanks Jim MacDonald Design + Engineering Dept. Solar Energy Systems, LLC Brooklyn, NY 11222 www.solarEsystems.com<http://www.solaresystems.com/> From: [email protected] [mailto:[email protected]] On Behalf Of Phil Undercuffler Sent: Sunday, July 18, 2010 9:09 PM To: RE-wrenches Subject: Re: [RE-wrenches] battery boxes...and conductor bundling Off hand, I can think of two components to this -- conductor heating, and noise/impedance. From a conductor heating POV, the NEC is fuzzy on specific distance but the general rule is to not bundle conductors for lengths greater than 18', or standard derates would need to be applied. With the costs of copper, I think you'd want to avoid unnecessary increasing of cable size wherever possible. >From a noise and impedance POV, I'd ditto what William Miller says but add >twisting the cables if possible, and with the possible additional caveat of >conductors of opposite polarity serving the same device. In most systems the >DC negative (usually) conductors are common and therefore this might be moot, >but it is theoretically possible to have a system with discrete components and >discrete conductors. (Not sure what that system would look like, but just >thinking out loud here...) In any case, in such a system bundling the >positive of one inverter with the negative of another inverter probably won't >have the positive impact desired. Phil Undercuffler On Sun, Jul 18, 2010 at 11:40 AM, Tom DeBates <[email protected]<mailto:[email protected]>> wrote: hello Wrenches, Since we usually are using the batteries in back-up applications and thus AGM batteries, we like to stack them. So we make-up a steel (2"X2" angle) rack, have our tinner bend-up an enclosure, and get all parts powder coated. Expensive, but last forever. On another note; what is the skinny on bundling conductors of same polarity?.....Ok, bad? Searched the archives and the Internets and couldn't find a satisfactory answer. thanks, tom Tom DeBates Habi-Tek 524 Summit St. Geneva,IL. 60134 630-262-8193 fax 630-262-1343 _______________________________________________ List sponsored by Home Power magazine List Address: [email protected]<mailto:[email protected]> 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<http://www.re-wrenches.org/etiquette.htm> Check out participant bios: www.members.re-wrenches.org<http://www.members.re-wrenches.org>
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