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Thread: Multi-Strand Wire (100+ vs 8)
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09-12-2022, 06:56 PM #11
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Sorry, but this is incorrect. What you are describing is called "skin effect" and is directly a function of frequency. At DC (0 Hz), given sufficient distance from a termination, the current flows through entire cross section of the wire. Resistance/current carrying capacity is strictly a function of the TOTAL cross-sectional area (# strands x cross-sectional area of each strand) with DC current. Skin effect usually (for our size wires/strands) does not become an issue until you get into a few 10's of kilo hertz frequencies (10~20kHz). For very large STRAND sizes (say around 1") it is lower, but still in the 100's Hz range.
Chris
ChrisChris & Karen
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09-12-2022, 07:33 PM #12
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Thx Chris….I checked out when he brought up DC flowing on the surface. @chemist308 do an internet search on “skin effect” if u want to read about it. Otherwise it’s about the second level electromagnetics course toward a EE degree. That was many moons ago for me.
Larry and JoAnna
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09-13-2022, 04:56 AM #13
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Well maybe I've not explained my self well. I am not referring to frequency related skin effect. Maybe my understanding of electricity and surface area is incorrect. But why then, is solid or limited strand #8 wire good for 40 amps while extremely fine #8 wire such as DLO, DEL, good for around 80amps? In AC or DC applications.
Not sure if this is related enough to the op's question to continue. If you know why, Maybe PM me Larry? I'm always willing to learn.2018 Dodge 3500 6.7 Cummins SRW w/Aisin
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New to RV'ing since 1997
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09-13-2022, 07:33 AM #14
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It’s the application and temp rating.
NEC table 310-17 is for single conductors in free air, dlo would be an RHH insulation type, 90deg C rating of #8 is 80a.
NEC table 310-16 is for up to 3 conductors in a raceway. For 90deg C in this application it’s derated to 55a, and at 60deg C it’s derated even further to 40a.Larry and JoAnna
‘23 Chevy 3500HD CCLB DRW High Country 6.6L Diesel, ‘22 Solitude 310GK-R, Hensley BD5
MORRyde 8k IS, QD8000 Genny, Dual 5kVA Quattros
Dual SOK 48V 100ah Server Rack Batts (10kWHr)
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09-13-2022, 03:54 PM #15
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Chris & Karen
Fort Collins, CO
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2018 Solitude 310GK - Sold 7/2023
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09-13-2022, 10:33 PM #16
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Wow there's a lot of really good technical info in this thread. I almost feel bad doing it, but I just couldn't sleep right knowing what the owners manual for my charge controllers said. So I got my hands on some 4AWG welding cable which was what I originally wanted to use before the guy at the solar company talked me out of it. This evening we pulled fish tape down to the pass through using the wire lugs on the #8 wire. Then we pulled the welding cable up, lubing it with wire wax--a huge thanks to my Dad for suggesting wire wax. I'd never heard of the stuff. All 4 cables are bolted onto bus bars in the box on the roof.
Tomorrow I'll cut the cables to length, tin their ends with electrical solder and install them into the cut off breakers and the charge controllers.2018 Grand Design Reflection 337RLS
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09-17-2022, 02:32 PM #17
In my opinion, using solder to tin the ends is not needed. More important is to make sure you have a good solid cold weld crimp. And that’s coming from someone (me) who went complete overkill on my solar wiring
Btw- sounds like it’s probably too late but if you do in fact want some truly bomber 8awg PV wire let me know! It’s expensive but the best. It’s 8awg, completely tinned, multi strand (read high strand count), and of course PV rated and UL listed.
With all that being said and reading your last post, how did everything go if you already finished?
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09-17-2022, 04:48 PM #18
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To all who claim the "skin effect" applies to DC...I'm open to reconsider what I learned in college physics and electronics if anybody can present more than an opinion. https://www.allaboutcircuits.com/tex...e-skin-effect/
bdcolvin
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09-18-2022, 09:24 AM #19
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2018 Grand Design Reflection 337RLS
2020 Ram 3500 SRW
https://c2.staticflickr.com/8/7803/4...56f2161a_m.jpg
frame flex problems
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