Main fuse rating

[Vicario]

I have been using a 9KW shower for many years without a problem; my main fuse is rated at 60amps. Recently a neighbour had a small downstairs toilet/shower room re-fit and I had a 'viewing'. He has a similar shower, (although rated at 9.5KW) and he said that the people who fitted it were a bit worried that his main fuse is only 60amps. He (like me) has no other high power appliances (we have gas ovens and no electric radiators etc.).
My electrician did point this out to me too some years ago but was happy that I had nothing else in the house that could compromise the main fuse. My question is this:
Is the fuse size restriction based solely upon the fact that other appliances in the house might blow the fuse when the shower is in use or are there other reasons?

 

[ericmark]

I have two electric showers, (two bath rooms and a shower room) two kitchens both with electric cookers, and oil central heating, house on 60 amp fuse, all three floors, so don't worry.

 

[Harry Bloomfield]

If it blows, they might be able to uprate it, but it depends on the rating of the supply cable. Usual ratings are 60, 80 100amp. Your shower in use, will draw around 37 amps, leaving 23 amps for other purposes. 23 amps is quite a lot, where there are no electric ovens or electric heating and it will not blow at 60amps immediately. It would need a sustained large, overload to be blown.

 

[Vicario]

Harry - would that be the cable coming in from the street or the thick ones going from the fuse to the meter (tails?)?

 

[Harry Bloomfield]

Really, both, but the tails are an easy swap.

 

[DIYinBerks]

Also be aware that if you have the fuse uprated, you may need to have the meter tails uprated as well.
We had ours changed from 60A to 100A some years ago; the supplier did that for free (maybe not today!) but we had to arrange to get the cables to the consumer unit changed to a bigger size - 25mm.