HELP with immersion heater problem.

[turnstone]

Just moved into flat and hot tank is hot all the time, I don't have any control over the immersion heaters. The "restricted" E7 unit seems to be working OK but the "un restricted" unit just never switches off? We have two switches in kitchen and I have had them switched off now for 48hrs but still have very hot water? Carried out basic voltage check from switch to immersion in JB and strange result when switched on 240V when off 415V???? even more confused now!!!!

 

[Richard Burns]

You should not be able to measure 415V at any point in a flat as the supply should be single phase.
If you have a fuse box or consumer unit, possibly located outside the flat, see if you can identify two immersion heater circuits, they are likely to be in different consumer units, I would recommend that you switch both off and call an electrician to identify the fault, this sort of result could be very dangerous.
It may be a good idea to switch off the entire off peak consumer unit if this will not leave you without heat.

 

[turnstone]

My meter and E7 module are adjacent to the fuse board inside flat, there is no logical reason why I can measure 415v at the JB and at the immersion heater but that is what it said, the reading out of the switches was normal 240v. The problem with the switches is that the unrestricted switch will not turn off the supply the power is still on to the immersion heater despite the switch being in off position? I can not track down the un restricted isolator or fuse don't seem to have one in the consumer unit, the restricted unit has its own separate isolator adjacent to the CU.

 

[HandySparks]

Some photos of the relevant equipment would be useful. (You may have to increase your post count or contact a mod to allow this?)

 

[Octopus]

How old is your property? Older installs often had the immersion on the socket circuit.

 

[Richard Burns]

When you say you have tested voltage, with what instrument did you test and between what points were you testing?
The presence of 415V indicates that there are two phases present in your supply (which is very unlikely unless the supply for another flat has been crossed with yours, however the readings given cannot be reconciled with a standard wiring arrangement.
If you did have two phases present in anything other than heating you would have had problems with other equipment.

 

[Guest77]

Just moved into flat and hot tank is hot all the time, I don't have any control over the immersion heaters. The "restricted" E7 unit seems to be working OK but the "un restricted" unit just never switches off? We have two switches in kitchen and I have had them switched off now for 48hrs but still have very hot water? Carried out basic voltage check from switch to immersion in JB and strange result when switched on 240V when off 415V???? even more confused now!!!!

Agree totally with Richard, one thing to add, how have you tested the 415 volts? what test equipment? is it calibrated? and what qualifications have you got to ensure the reading is accurated based on your testing methods?