Why does my shower trip the fuse after 5 mins?

Question

the shower is an electric one that is connected to a 32 amp fuse in the fuse box and is connected to the cold water supply only. When it was first fitted it worked fine but as time has gone on it started to cut outand wont switch on for a couple of seconds

Answer 1

I'll answer this even though you have not given the right amount of information.

An electric shower works off of an on-demand hot water heater (tank-less).  The tank-less water heater is set to heat the water up to a certain temperature.  Each degree of heat it adds requires a certain amount of energy (varies based on water heater).  So for the first 5 minutes it is pulling water from a pipe that has been sitting inside your "conditioned" home.  Thus that water has been heated to near room temperature.  

Lets say you take your showers with 100 degree water.  The room temperature is 70.  So it only needs to heat it 30 degrees for the first 5 minutes.  

After 5 minutes you have depleted the water in your pipes (the ones inside your home) and it is now pulling water from it's source (city or well).  That water is at ground temperature, usually around 55 degrees.  So now the water heater needs to heat the water 45 degrees.  That takes 1.5 times the amount of energy that it needed to heat from 70 degrees.  

Over time any electrical component becomes a little less efficient.  So maybe when it was first set up a 32 amp fuse would have been sufficient to heat water 45 degrees.  But over time it has become less efficient and it now requires more than 32 amps to create that amount of heat.  Thus - your fuse is insufficient.  

Problem is that your wiring may not be of a large enough diameter to move more than 32 amps so increasing the amperage of the fuse on your own may result in the spontaneous combustion of your home.  Pay an electrician to look at the shower's heater and to determine if you can increase the amperage of that circuit.

Answer 2

A 32 amp MCB (circuit breaker) Not a fuse I hope?? will carry about 8 Kw for ever, but if you have a 8.5- 9.00 or higher rated shower then the mcb will start heating up due to the overload, and eventually trip. Maybe the house is warmer in the area of the mcb, this ambient temperature will decrease the current carrying capacity of the breaker, which is usually set for 20°C. OR maybe the mcb is getting old and out of calibration. You could also check the cable size and possibly fit a 40amp breaker, if other conditions permit.

Answer 3

Electric showers will cut off if water pressure drops. There may also be a fault with the internals, if the shower is under warranty call the manufacturer or replace it.

Answer 4

You got the answers to this yesterday when you asked the question.

Answer 5

yes i agree or take a bath instead