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[Jeffmo]

electril Mira Sport shower 9.5Kw , how do i work out fuse rquired is it ohms law that i should use .Cheers Jeff

[sparx]

Yes, for resistive loads such as heating elements can treat as if D.C. so :
9,500w divided by 230v = 41.30Amps therefore nearest fuse fuse size available 45A, this will require a 10 mm cable if 'enclosed in an insulated wall' ie chased in flush , or possibly a 6mm cable rated @46A if 'clipped direct' ie on surface depending upon lenght of run from con.unit.
for 6mm cable volt drop is 7.3 mV per amp per meter, so at say 20 meter run this would be:
7.3 X 41.3 X 20 =60.298 divided by 1000 to change to Volts=6.029 volts dropped which is within max allowed of 9.6volts
regards SPARX

[Jeffmo]

the original cable is wat looks like 4mm and it was connected to separate fuse at 40 amps , all cable clipped . Oh dear wat is regs regarding existing . Cheers Jeff

[sparx]

Ooops, for clipped direct (ie surface run) from table 4D5A, 4mm current rating is 37A if PVC cable.
So either cable is bigger than 4mm or your fuse is already too large....
the max size shower you could have on a 4mm is 8.5 kW assuming a short run to fuse box, ie less than abt 20 meters, regards Sparx

[Jeffmo]

The cable is a difficult one trying to measure , however the run which is all clipped is only about 6m max , what fuse should be in there ? confused . com .Regards Jeff