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GeneralRe: USB for Power? Pin
James Curran12-Feb-21 5:37
James Curran12-Feb-21 5:37 
GeneralRe: USB for Power? Pin
trønderen12-Feb-21 7:23
trønderen12-Feb-21 7:23 
GeneralRe: USB for Power? Pin
ElectronProgrammer12-Feb-21 7:53
ElectronProgrammer12-Feb-21 7:53 
GeneralRe: USB for Power? Pin
trønderen12-Feb-21 9:34
trønderen12-Feb-21 9:34 
GeneralRe: USB for Power? Pin
ElectronProgrammer13-Feb-21 7:59
ElectronProgrammer13-Feb-21 7:59 
GeneralRe: USB for Power? Pin
trønderen13-Feb-21 12:54
trønderen13-Feb-21 12:54 
GeneralRe: USB for Power? Pin
ElectronProgrammer15-Feb-21 2:41
ElectronProgrammer15-Feb-21 2:41 
GeneralRe: USB for Power? Pin
trønderen15-Feb-21 4:20
trønderen15-Feb-21 4:20 
ElectronProgrammer wrote:
You didn't said 2A before. You said "almost 200W" which gives 10A.
True - you were the one setting the limit for 4 sqmm cable at 2A. So I made the calculation of heat loss for what you consider the maximum handling capacity of a 4 sqmm cable. You can easily repeat the calculation for 10A - in fact, the voltage loss is proportional to the current, so for the 4 m of 4 sqmm cable, the loss is 0.35V, and for the 4 m of 2.5 sqmm cable 0.56V.

However, we are here talking about extreme worst case examples. In my house, no 12V equipment lies at the end of a 4+4 m cable stretch; the typical is half of that. Furthermore: No single branch will carry 10A (or even close). As I wrote in an earlier posting: You will of course protect every single branch with fuses dimensioned for the expected load on that branch. -- That is even if the cable dimension would allow for a higher current than your expected load. If you cause a shortcut, the fuse should blow, rather than the cable overheat. This is part of knowing how to do it.
ask someone with knowledge to validate your setup before starting to build it, preferably someone with knowledge about your local laws
Our Norwegian laws set a limit on the total effect of you 12VDC network at 200 W, and you must stay below 50V. Cabling must be available for inspection everywhere; if they go through walls or ceilings, they must run in metal pipes (in principle: Non-burnable material, but for all practical purposes, that is metal). I am replacing cornice with similar-looking cable gates with fronts that can be flipped off to get at the cables. (Side remark: The cabled Ethernet runs in the same cable channels.)

12VDC networks have a long tradition in faraway mountain cabins in Norway, and we have a multitude of shops selling all sorts of parts for setting it up: Cabling, fuse boxes, water pumps, plugs and sockets, lead-acid batteries and solar panels. You can buy all sorts of lamps, fans etc. made for 12VDC, intended for cabin use. We just don't use it much in regular homes. It is easy to find people with a good understanding of what you can and should do, and what you shouldn't, and the common knowledge level is high. We know because we need to know. We have two big Norwegian language websites, named ByggeBolig.no (like BuildingAHome) and ByggeHytte.no (like BuildingACabin). In both forums, various issues related to low voltage power is regularly brought up. Although the majority of posters are DIY guys, several professional craftsmen, including electricians, are active and provide professional advice.
GeneralRe: USB for Power? Pin
glennPattonWork312-Feb-21 8:08
professionalglennPattonWork312-Feb-21 8:08 
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Chris Maunder11-Feb-21 6:15
cofounderChris Maunder11-Feb-21 6:15 
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Mircea Neacsu11-Feb-21 6:22
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trønderen11-Feb-21 9:14
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trønderen11-Feb-21 12:15
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Jörgen Andersson11-Feb-21 20:21
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trønderen12-Feb-21 12:15
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Mycroft Holmes11-Feb-21 10:21
professionalMycroft Holmes11-Feb-21 10:21 
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Gary R. Wheeler11-Feb-21 15:31
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OriginalGriff11-Feb-21 8:17
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trønderen11-Feb-21 9:23
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