Rigid wire - max current/wattage

[thunderhorse]

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.

[AnOther]

There is lots of useful information with easy to read charts HERE and HERE

In essence 2.5mm = 15A, 4mm = 30A and 6mm = 75A

Length only becomes relevant if you are drawing near maximum loads for a given cable size. 15m should not be a concern though.

 

[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

[AnOther]

Sorry, my mistake, all that converting from AWG to cross section [:$]

 

[Nick Trollope]

[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.....

[thunderhorse]

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.

[trees 2]

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.

[powerdesal]

Disjoncteurs for sockets wired in 2.5mm CSA are 20 amp.

[thunderhorse]

I'll take that as a yes.

[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.

[thunderhorse]

[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?

[trees 2]

[quote user="powerdesal"]Disjoncteurs for sockets wired in 2.5mm CSA are 20 amp.

[/quote]

<Rolls eyes>

Not what it said in MY books[:(]

[powerdesal]

Best we compare books then

[powerdesal]

Trees is correct, disjoncteurs for sockets in 2.5 mm sqr are 25A, fuses for sockets in 2.5 mm sqr are 20A

ref: Depannages et renovations electriques by Gallauziaux and Fedullo, pages 57 and 59

[Dave&Olive]

[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 20A

ref: 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

[thunderhorse]

So after 2 pages of thread we're talking about 4.5 kw max. Yes?

[Dave&Olive]

[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

[powerdesal]

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.

[thunderhorse]

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]