How would you approach this?

Vortigern · Apr 23, 2022

Customer wants to do away with E7 and fit new heaters. Modern ceramic type. Five of them. My view is too remove all the E7 gubbins and a new box with isolator as there are not enough ways to accomodate five new radial circuits. The existing SH's are on the left of the CU and are all radials. So repurpose these in a new box. I get the feeling I am missing something though. Not too sure if they go on another tariff what will happen to the E7 will they remove it or just switch it off or leave on on normal tariff????

Dartlec · Apr 23, 2022

Vortigern said:
Customer wants to do away with E7 and fit new heaters. Modern ceramic type. Five of them. My view is too remove all the E7 gubbins and a new box with isolator as there are not enough ways to accomodate five new radial circuits. The existing SH's are on the left of the CU and are all radials. So repurpose these in a new box. I get the feeling I am missing something though. Not too sure if they go on another tariff what will happen to the E7 will they remove it or just switch it off or leave on on normal tariff????

Unless they change tariff, the E7 applies to the whole installation from 12-7 anyway (or whatever the hours are in that location), even if you've removed the heater loads.

So if you fitted a new box and you leave the immersion where it is, and they use washing machine or similar regularly over night then it might still be worth keeping the E7 tariff - otherwise they could change to a normal tariff.

Another option is to change the line feed to the off peak main switch to the normal rate feed (the neutral is shared) and fit RCBOs for the heater radials - they are still available for that board - though I think in type AC only last time I looked.

If they wanted to then keep the E7 tariff for the immersion you could then run that locally via a timer.