aruba5er wrote: What randrx2 said. How are you going to measure the differance. But more importantly why do you want to? More surface area, lower resistance Skin effect, they say the current runs on the outside of the wire, not thru it. Concernd? get a bigger wire.
Since we are dealing with DC and "0"hz...there is minimum to no skin effect.
Stranded wire of the same ga as solid will be a bigger diameter wire.
Cm (circular mil's) for each strand of stranded wire is in the calculation for wire ga.
Measuring very low resistance is done on a MILLIOHMETER using 4 terminals to establish NULL.
Man this topic is like mulling over whether or not a tire has .75200200" tread depth versus .75200202" tread depth.
Isn't it worthwhile to discuss how the wire is going to be terminated and the manner and method of attachment? About five hundred times as important as the vagaries of strand count, but sadly, never discussed here.
Quote: More surface area, lower resistance Skin effect, they say the current runs on the outside of the wire, not thru it.
With DC, skin effect does not exist. The only factor is the total cross-sectional area of the conducting material. At 60 Hz., skin effect does not exist unless the conductor diameter (with copper) is about 3/4 inch or greater. The only thing that matters is cross-sectional area. http://en.wikipedia.org/wiki/Skin_effect
Ordinary stranded wire does not help with skin effect. It behaves exactly the same as solid wire. A special stranded wire does exist to help with skin effect. Its strands are individually insulated and woven in a specific pattern. http://en.wikipedia.org/wiki/Litz_wire
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Calulator is for wires in a bundle....not strands in a wire.
Jim
Thanks for that info.
mexbungalows wrote:
Isn't it worthwhile to discuss how the wire is going to be terminated and the manner and method of attachment? About five hundred times as important as the vagaries of strand count, but sadly, never discussed here.
The reason for this info is,
I screwed up, when I did the detailed to scale diagram of my roof top measurements of the wire distance of the solar panels to the inside mounting location to the CC.
I need to add about 6' to each cable,(OEM cable size is 12 AWG from Jct box of panels and pigtail length is 30"). I had original run the roof wires the shortest distance.
And in the final diagram I used straight lines and corners etc with all the wires being bundled together as they join up just before the drop down to the reefer vent to the inside mounting place next to the OEM 9260 convertor, needing the 6' more length per cable.
I have a choice to make at this time, 7 strand,#10 size, multi stand #10 size, or 2-#8 AWG wire, red/black wrapped in white covering, multi strand tinned Boat wire, using swagged copper lugs, filled with dielectic grease and 2 layers of adhesive heat shrink tubing over lug/wire joints.
1. Add the needed 6' of cable to the existing cable with a butt connectors, to finish run to CC.
OR
2. Buy new proper length cables/wire from panels to CC in one whole complete length, with one of the 3 choices listed for wire size.
I personally like the complete new cable/wire in one complete length for less corrosion problems while on the roof, using the multi strand cable/wire for ease of bending/fitting etc as compared to the 7 strand cable/wire and I am also shooting for 1% drop resistance if possible.
Tia,
Don
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Isn't it worthwhile to discuss how the wire is going to be terminated and the manner and method of attachment? About five hundred times as important as the vagaries of strand count, but sadly, never discussed here.
Soooooooooooo correct, but we must correct misinformation do we not?
As for termination and connections...I'll take the five hundred and raise you another 500!!!! 1000 time more important.
At 10 amps I have seen .1volts drop through a resettable automotive breaker. That's not including the wire length and connections needed to make the connection from the charging device to the battery!!
At 10 amps, .1 or more drop through a constant contact solenoid used for coach to house battery charging isolation.
At 50 amps a .2 volt drop through a 100amp cutoff switch.
These are just a tip of the iceberg that keeps our charging systems from functioning correctly.
Not sure I understand, but if all the wires are 6 feet short then why not join the pos and the negs to busses in a junction box and run just two fat wires from there to the controller? Or is that what is intended?
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BFL13 wrote: Not sure I understand, but if all the wires are 6 feet short then why not join the pos and the negs to busses in a junction box and run just two fat wires from there to the controller? Or is that what is intended?
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BFL13,
Yes, that is what I had intended to do, but being 6' short, the ends are in the reefer vent area where I cannot get access to, I wanted the Jct box in the main CC/convertor section, easier access etc.
So,I either have to extend 6' on each or move the Jct box to the roof and then run HD cables down to the CC about 10-11' below in the convertor area, or make new longer cables to reach the proper area.
I wanted to stay off the roof as much as possible, to save wear and tear on the rubber roof coating.
Tia,
Don
I am up on the roof all the time and it is still there
IMO, no reason you can't haul the wire ends up to the roof and attach the new junction and the two wires from that and drop the whole thing down . The junction box can dangle in mid air half way down the vent, who cares?
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