thunderhorse Posted July 21, 2008 Share Posted July 21, 2008 Is there a formula or rule of thumb for working out a safe maximum current/wattage on various cross-sections of rigid wire, particularly 2,5mm, 4mm and 6mm? (Max length of gaine, say, 15m.)Many thanks. Link to comment Share on other sites More sharing options...
AnOther Posted July 21, 2008 Share Posted July 21, 2008 There is lots of useful information with easy to read charts HERE and HEREIn essence 2.5mm = 15A, 4mm = 30A and 6mm = 75ALength only becomes relevant if you are drawing near maximum loads for a given cable size. 15m should not be a concern though. Link to comment Share on other sites More sharing options...
trees 2 Posted July 21, 2008 Share Posted July 21, 2008 Why only 15A for 2.5 mm sq? My house has 2.5mm sq conductors wired to both 25A and 32A mcb's Link to comment Share on other sites More sharing options...
AnOther Posted July 21, 2008 Share Posted July 21, 2008 Sorry, my mistake, all that converting from AWG to cross section [:$] Link to comment Share on other sites More sharing options...
Nick Trollope Posted July 21, 2008 Share Posted July 21, 2008 [quote user="trees 2"]Why only 15A for 2.5 mm sq? My house has 2.5mm sq conductors wired to both 25A and 32A mcb's[/quote]I'm not sure you should have a 2,50mm2 circuit attached to a 32A disj..... Link to comment Share on other sites More sharing options...
thunderhorse Posted July 22, 2008 Author Share Posted July 22, 2008 From the charts and as best as I could work out, we're looking at 20 amp and 4.8 kw. Is that about right?Cheers, guys. Link to comment Share on other sites More sharing options...
trees 2 Posted July 22, 2008 Share Posted July 22, 2008 Isn't that the disjoncteur size for sockets? It could be me, perhaps they are all 25A? I'm here. so can't go and look at the moment. Link to comment Share on other sites More sharing options...
powerdesal Posted July 22, 2008 Share Posted July 22, 2008 Disjoncteurs for sockets wired in 2.5mm CSA are 20 amp. Link to comment Share on other sites More sharing options...
thunderhorse Posted July 22, 2008 Author Share Posted July 22, 2008 I'll take that as a yes. Link to comment Share on other sites More sharing options...
powerdesal Posted July 22, 2008 Share Posted July 22, 2008 Not strickly a yes, you have assumed 240v, its not in France, at least mine isn't. I seem to remember reading 228v on my meter at one time. Link to comment Share on other sites More sharing options...
thunderhorse Posted July 22, 2008 Author Share Posted July 22, 2008 [quote user="powerdesal"]Not strickly a yes, you have assumed 240v, its not in France, at least mine isn't. I seem to remember reading 228v on my meter at one time.[/quote]But we're still talking about 4.5kw @ 20 amp @ 230v, or thereabouts? Link to comment Share on other sites More sharing options...
trees 2 Posted July 22, 2008 Share Posted July 22, 2008 [quote user="powerdesal"]Disjoncteurs for sockets wired in 2.5mm CSA are 20 amp.[/quote]<Rolls eyes>Not what it said in MY books[:(] Link to comment Share on other sites More sharing options...
powerdesal Posted July 22, 2008 Share Posted July 22, 2008 Best we compare books then Link to comment Share on other sites More sharing options...
powerdesal Posted July 23, 2008 Share Posted July 23, 2008 Trees is correct, disjoncteurs for sockets in 2.5 mm sqr are 25A, fuses for sockets in 2.5 mm sqr are 20Aref: Depannages et renovations electriques by Gallauziaux and Fedullo, pages 57 and 59 Link to comment Share on other sites More sharing options...
Dave&Olive Posted July 23, 2008 Share Posted July 23, 2008 [quote user="powerdesal"]Trees is correct, disjoncteurs for sockets in 2.5 mm sqr are 25A, fuses for sockets in 2.5 mm sqr are 20Aref: Depannages et renovations electriques by Gallauziaux and Fedullo, pages 57 and 59[/quote] hi ok .. my book says 16amp fuse or 20 amp disjoncteur for 2.5 mm for 20amp fuse or 25 amp disjoncteur for 4 mm just for info dave Link to comment Share on other sites More sharing options...
thunderhorse Posted July 23, 2008 Author Share Posted July 23, 2008 So after 2 pages of thread we're talking about 4.5 kw max. Yes? Link to comment Share on other sites More sharing options...
Dave&Olive Posted July 23, 2008 Share Posted July 23, 2008 [quote user="thunderhorse"]So after 2 pages of thread we're talking about 4.5 kw max. Yes?[/quote] hi ok must be .... V/I=R 220 v X 20 amps =4400 watts going back to the 32 amp fuse posting ......... is not that a UK ringmain fuse ??? Dave Link to comment Share on other sites More sharing options...
powerdesal Posted July 23, 2008 Share Posted July 23, 2008 Dave (et al),The copy of "Depannages et renovations electriques by Gallauziaux and Fedullo, pages 57 and 59" definitely says what I said above, but....."L'Installation Electrique - Comme un Pro" also by Gallauziaux and Fedullo states as I said originally - 20A disjoncteur for a 2.5mm socket circuit it also states a 16A fuse for same, as you say above.Therefore a conflict between two reference books by the same authors.I usually use the L'Installation Electrique reference but today was the first time that I read my copy of Depannages et renovations electriques, as the Comme un Pro book is in France. I then remembered an English translation on a memory stick that I found a few minutes ago.So, take your pick. 4.5kw still stands as far as I can see.edit. W = V x I x Cos phi so if you take volts as nominal 220 and pf as 1 then 4400W is right, I happen to measure 228 v so its 4560W,4.5 kw seems a good limit. Link to comment Share on other sites More sharing options...
thunderhorse Posted July 24, 2008 Author Share Posted July 24, 2008 Many thanks, guys. The rear of the house currently (no pun intended - hell, why not?) is supplied by two major cables: One supplies the bathroom only, the other supplies a variety of sockets, lights and switches to the rest of the rear.I was considering simply extending the cables as part of the grenier renovation, or alternatively dividing up the looms and running two more gaines to the rear from a secondary tableau. Think I'll go with the latter - it'll give me more flexibility in the future.Many thanks again. [:D] Link to comment Share on other sites More sharing options...
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