Matt, Right-on. I meant solid smaller gauge wire and multi-stranded larger gauge wire as compared to finely-stranded wire.
Dave, Almost every electrician has nipped off a strand or more to get a conductor to fit into undersized connectors. Older model charge controllers and inverters were notorious for undersized connectors. Some electricians are very skilled at fitting lugs and/or putting tape over "down-sized" wire ends. I'm not justifying this practice. Just reminding manufacturers to provide big enough connectors that are securely fastened to their equipment (not tacked onto a circuit board) and to provide practical strain-reliefs. Joel Davidson ----- Original Message ----- From: Matt Tritt To: RE-wrenches Sent: Wednesday, August 05, 2009 1:29 PM Subject: Re: [RE-wrenches] PV System Design Compromises (was solid vs stranded AC vs DC) Joel, Changing any wires connected to a SW to solid core would be virtually impossible because of the almost impossible to connect with stranded wire connection blocks. Remember how ^$*! tight the spaces are in those babies? Living with a marginally relevant inefficiency from stranded seems a low price to pay for being able to connect the bits and pieces to each other. Non? Matt T Joel Davidson wrote: Dave, I agree. but are we talking about 2% voltage drop, resistance, or power loss? What I got from this discussion about solid vs. stranded wire (1) use solid copper wire and (2) keep I2R losses low and (3) if you use stranded wire, be very diligent when tightening connectors. Anything else? Wrenches make design compromises every day. My 11 year old grid-tied system is an example: - Siemens SP70 modules because SP75s were unavailable. - Trace SW4048 at 65% efficiency because higher efficiency non-battery inverters were less reliable. - Low-rise, low-tilt angle array because Culver City did not allow PV arrays to be visible from the street. - And now, making improvements on a system that is working flawlessly for almost 100,000 hours does not make cost vs. benefits sense. Joel Davidson ----- Original Message ----- From: "Dave Click" <davecl...@fsec.ucf.edu> To: "RE-wrenches" <re-wrenches@lists.re-wrenches.org> Sent: Wednesday, August 05, 2009 5:58 AM Subject: Re: [RE-wrenches] solid vs stranded AC vs DC 2% loss is significant, but I think that Darryl was saying that the resistance for stranded wire was 2% higher than solid. So if you had a 3% voltage drop in your system with stranded wire, you could rewire the system with solid wire and have a voltage drop of (3% x 0.98) 2.94% at peak production; that's less than 1 kWh/yr per kW installed. DKC -------- Original Message -------- Subject: Re: [RE-wrenches] solid vs stranded AC vs DC From: Joel Davidson <joel.david...@sbcglobal.net> To: RE-wrenches <re-wrenches@lists.re-wrenches.org> Date: 2009/8/3 20:31 2% loss from any resistance source over 25 years is significant. ----- Original Message ----- From: "Darryl Thayer" <daryl_so...@yahoo.com> To: "RE-wrenches" <re-wrenches@lists.re-wrenches.org> Sent: Monday, August 03, 2009 2:04 PM Subject: Re: [RE-wrenches] solid vs stranded AC vs DC Yes, that is what the code book and my electricians handbook says, but 2% is very little. I would think that passing through a conduit hole is larger than that. Darryl --- On Mon, 8/3/09, Matt Tritt <solar...@charter.net> wrote: From: Matt Tritt <solar...@charter.net> Subject: Re: [RE-wrenches] solid vs stranded AC vs DC To: "RE-wrenches" <re-wrenches@lists.re-wrenches.org> Date: Monday, August 3, 2009, 3:49 PM Darryl, Say what?! This would seem to indicate that solid core is actually better for DC than stranded wire. Can this possibly be true?? Matt Darryl Thayer wrote: I looked in the code book and found stranded wire has about 2% higher DC resistance than solid, Chapter 9 table 8, and that for AC resistance the same value as DC resistance to within the table accuracy Chapter 9 Table 9 This table points out that for AC resistance it is important to know the conduit system, as the reactance will have an effect. With AC it is important to never allow a single wire to pass through a metal surface as this will induce eddy currents and magnetic effects into the metal causing voltage drop and heating. --- On Fri, 7/31/09, jay peltz <j...@asis.com> wrote: From: jay peltz <j...@asis.com> Subject: Re: [RE-wrenches] solid vs stranded AC vs DC To: "RE-wrenches" <re-wrenches@lists.re-wrenches.org> Date: Friday, July 31, 2009, 10:01 PM Hi Darryl, But what are the differences and when do they come into play? On Jul 31, 2009, at 7:25 PM, Darryl Thayer wrote: Well there is very slight differences between AC and Dc But this difference is so slight that it has no effect on anything we will do. Darryl --- On Fri, 7/31/09, jay peltz <j...@asis.com> wrote: From: jay peltz <j...@asis.com> Subject: [RE-wrenches] solid vs stranded AC vs DC To: "RE-wrenches" <re-wrenches@lists.re-wrenches.org> Date: Friday, July 31, 2009, 7:00 PM HI All, I'm trying to understand this wire issue. Whether or not there is a difference between stranded or solid wire for DC or AC. 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