tripping mcb pulsacoil 2000

hi, i have a problem with a pulsacoil 2000.
when i first visited the fuse for the lower immersion had blown, replaced it , all working, couldn`t get it to blow again or find any faults.
since i left it keeps tripping the mcb. the upper immersion can be left on and functions correctly.
when mcb is reset it appears to work ok , i have tried satisfying the stat and it does what it`s supposed to. . from what i`m told it usually trips after about an hour. i am wondering if when up to full temperatue the immersion has a fault that trips the mcb? as they seem pretty expensive i am reluctant to try when i am not sure as i doubt customer will be happy to pay if fault still there.
any advice/ ideas please?

Tested the immersion heater?
19 ohms.
Mike
MGC/H2O
Norfolk

no i haven`t measured it. do you think if the measurement is out it could cause this fault? not come across one before that takes this long to trip?

19 ohms across the element.
Check the element to earth as well.
Also if the is a lot of sludge in the unit.
Or the element is badly scaled.
That can cause a later problem.
Checked the flexes? All the connections ?
Mike
MGC/H2O
Norfolk

all flexes and connections appeared ok and everything working as it should while i was there. i guess i could swap the feeds to the immersions and see if it trips the other side?

worth a try.

thanks for your replies, i`ll go back and test and swap feeds if tests out ok.i`ll post what i find. what would you recommend as an inhibitor?

X100

Carry out an insulation resistance test on the bottom element, if it is shorting, then replace it. You should also do that test on the flex cable and supply in case it is nothing to do with the immersion but the installation wiring.