Hi,
We've got an old style consumer unit, which had a 45A MCB for the electric shower in it when we moved in a few years ago. I've never tried touching the MCB or the CU after using the shower, so can't comment on whether it used to get hot or not.
However, a few days ago, while the shower was running I noticed a sharp electrical smell, which I'd never smelled before, and opening the cabinet in which the CU sits, it was clear the smell originated there. The 45A MCB was hot to the touch, as was the CU surrounding it.
I replaced the 45A MCB with a new 40A MCB (couldn't find a 45A one). A short run of the shower (60 seconds) proved fine, but a longer run eventually led to the MCB getting hot, and again, the faint electrical odor.
The CU did not get hot this time, but the shower didn't run for as long as it had the first time.
We have an electrician coming out next week to investigate anyway, but wondered if anyone had any experience of something similar and knew if I was over-reacting, or if there's likely to be an issue somewhere in the shower or the wiring between it and the CU.
Nothing has been changed in the last 8 years, but that doesn't mean wiring hasn't degraded, etc.