On Sat, 15 Dec 2018 14:50:48 -0000, "Kristy Ogilvie"
wrote:

I'm in the process of fitting a Triton electric shower, and was being nosy. I noticed it has a thermal cutout situated where the water leaves the heater unit, this: http://www.datasheet-pdf.info/entry/36TXE11

That cuts out at 105C (ouch!) and it's also switching 20 amps when it's rated at 10 amps, AND it only cuts off ONE of the two elements.

It does have another cutout on the other end of the heater unit, which cuts them both off.

1) Why have two cutouts?
2) Why overload the first one?
3) Why only cut off half the power?

Are you sure about the part number? The 36T is a thermostat that can
be ordered with various set points. I doubt they would use the 105C
version for a shower. Perhaps other versions can switch 20A. As for
your last question, it is not being used as a safety cutoff like the
other one. It is being used as a thermostat. Leaving one element on
full time while switching the other probably works well for their
intended use.