Lights dim when shower turned on

[mimerv]

I have just noticed that the house lights dim (very slightly) when I turn the electric shower on and stay dimmed until the shower is turned off. Does anyone think there is a problem or is this normal ?? Thanks

[stanleyman]

This is caused by voltage drop when the shower or other heavy load is switched on. Provided it is within certain limits and it is not overloading switchgear and cabling then it will be normal. Electric showers should have their own fuse box and a common mistake is to wire then into an existing consumer unit where it becomes overloaded.

[mimerv]

Many thanks Stanleyman, I'll go and check the fusebox.