Electric shower question

[ritly00]

I am trying to install an electric shower of 9.5kw. What capacity fuse do you think I would need to prevent the fuse from blowing? Right now I have a shower of 8.5kw and we're using a 30Amp fuse. It blows after about 10 minutes. Any ideas?

 

[DyslexicGrimsbySparkie]

at 8500W, you are pulling 37A + losses through the cable so a 40A MCB / fuse should be okay.

at 9.5kW you will be pulling 41.3A + losses through the cable so you will need a 50A.

Just for your information, you can work out the amp rating using this formula

Power = Current x Volts

where P is in Watts, Current in Amps and Volts in Volts. You need to allow a little as the current drawn is usually higher when the appliance starts up as everything is cold and its resitance is a little lower (hence more current draw) . Also you will lose some power through the cable.

 

[ritly00]

Thanks will try that out!

 

[Spark123]

Before you up the fuse size it is vital you check the size of the cable is adequate to carry the aditional current.

 

[securespark]

And don't forget while you're at it to check the isolator is rated at 45A, the CU can take the increased load without toasting, and your main fuse is bigger than 60A, and the tails are beefy enough.

You might also consider getting the supplementary bonding in the bathroom up to scratch, too.

Lots of things to consider, not just the protective device size......

 

[ban-all-sheds]

Before you up the fuse size it is vital you check the size of the cable is adequate to carry the aditional current.

When checking this, remember that the current carrying capacity of the cable varies according to where (in what) it runs, and whether it is bunched with other cables.

Also if it is too long its resistance will be too high for the MCB to trip quickly enough if there is a fault.

Lots of things to consider, not just the protective device size......