Well they say
"
All electrical wiring should be carried out by a competent electrician and be in accordance with
the latest I.E.E. Wiring Regulations. Each circuit must be protected by a suitable fuse and
double pole isolating switch with a contact separation of at least 3mm in both poles.
The immersion heater(s) should be wired in accordance with Diagram 7. The Live and Neutral
conductors should be connected directly to the combined thermostat/thermal cut-out to the
terminals marked A and B. The immersion heaters MUST be earthed. The supply cable should
be 1.5mm2
3 core HOFR sheathed and must be routed through either the cable grip provided
(lower housing) or the cable gland provided (upper housing 210 litre units and above only) with
the outer sheath of the cable firmly secured by tightening either the top bar of the cable grip or
the screws on the cable gland. Replace the housing cover(s) before operating. On the upper
housing (210 litre and above only) ensure that the threaded edge clip is in position to provide a
suitable thread for the cover scre"
Page 15 fig 7
http://www.heatraesadia.com/docs/Megaflo_systemfit_-_Issue_5_-_36005882.pdf
Obviously worded wrong even though the diagram agrees.
I,ll stick with a 2.5mm T&E on its own MCB to a double pole switch with a HOFR 2.5mm cable to immersion.