electric boiler keeps tripping fuse box

[tx200man]

hi, problem with electric boiler means no hot water.
looking for help in finding the fault.
what i have done:
1. checked fuse box, fuse intact and reset
2. reset water heater switch
everytime it seems its the bottom immersion that goes bang and re-trips the fuse box.

Stage 2 was to:
check wiring on bottom immersion heater on the tank, all checked out, however i removed the centre part, think its the temperature cut off switch, dont see any problems so put back in. basically it is now just as it was before i started.

reset fuse, boiler starts, heats water four 2 hours, turns off, during the night at some point the fuse trips...again.

did same thing as above and same thing happens after a short time.

Stage 3 was to:
re visit the wiring, check earths are connected to pipes, they are. on further inspection i notice that the top immersion heaters cable looks discoloured. i think the earth wire was arcing to the unit as there was signs of it and wire looked burnt out, (earth?) i cut it right back and rewired.

retested, boiler starts heats and later cuts out, reset box and boiler trips immediately.

i dont think this is the immersion heater itself as it does heat up, do i just need to buy a new termperature cut off (middle bit) or any advice on what to check next appreciated.

cheers

james

 

[Taylortwocities]

It sounds to me like the bottom immersion itself (off peak?) has a problem - this can be tested by someone with an Insulation Resistance tester.

Now you have got to step 3, it sounds like you may have complicated what was probably a simple problem. I'm guessing you may have introduced another fault by jiggling the wiring around as now something trips..
What is it, exactly that "trips" ?? Do you mean soemthing in teh consumer unit? Not the boiler itself, surely?

 

[tx200man]

Tripping the fuse at the fuse box was always the problem, the bottom immersion can easily be reversed, however i doubt that will help anything but it is what i will try tonight, then its all back to exactly the way it was.

The real question here is.
If an immersion is heating the water and only trips after a time, is it at fault or is it the wiring that is at fault The power is definately getting to the unit, strange that if it is faulty that it is tripping the fuse after a period of time, not straight away.

The wiring on the top immersion heater was clearly bad and rather than introduce a problem i most definately have solved a potential fire hazard, at one point 5 inches from terminals the bare wire was showing burn right through the insulation. luck i looked there as the loud bang that trips the fuse box definately comes from the bottom immersion heater.

 

[tx200man]

should have stated this from very beginning. This problem came about the day after a bad storm, the storm caused a power cut and the resulting problem with the boiler was the only problem in the house after.

 

[RF Lighting]

If there's a loud bang then something's definately not right. If it's taking two hours before it trips then it sound's like something is expanding when it eventually gets hot and causing the fault.

I think it's time to test the immersion with an insulation tester. This will either confirm or rule out altogether the immersion, and allow you to concentrate on the correct part of the installation which is causing the fault.

 

[tx200man]

can i use a multimeter or do i need specialist equipment for a insulation test

 

[Taylortwocities]

- this can be tested by someone with an Insulation Resistance tester.

It's an Insulation Resistance tester. It is not a tyre pressure gauge, its, not a Satellite Navigation device, it is not a multimeter. It's an Insulation Resistance tester.

Often called a "Megger". Megger is a manufacturer (In the same way as vaccuum cleaners are often called Hoovers).

It generates up to 1000volts DC and tests the integrity of an appliance, your immersion heater or installation cabling to ensure there is no connection, even a small one, typically between the device and earth.

Any competent electrcian will have one.

 

[tx200man]

Competent electrician ........ is what im trying to avoid. i cant afford it.

just to rule out the immersion heater thermostat i bought a new one and wired it up. same problem. the fuse box trips immediately.

is there anything i can do myself, i cant afford to buy more testing equipment so cant do an insulation test as wont be buying a tester, its just not cost effective.

yes i know at some point is likely i will need an electrician but first i want to rule out as much as possible to prevent a huge electrician bill.

convinced this is to do with the power cut. could i try wiring the immersion heater to a normal plug and use a power cable reel to another socket to see if heater will respond or?

 

[EFLImpudence]

These tests are not conclusive because, as has been said, the element may expand and/or bend when hot but you may find the problem.

Turn off main switch at the consumer unit AND remove immersion heater fuse.
(It's an immersion heater, not a boiler.)
Switch off Immersion heater switch.

Carefully remove immersion heater cover.

Set multimeter to 240V and test for dead ( 0V ) between immersion heater terminals (L & N; L & E; N & E).

Set multimeter to Ohms - lowest value first then, if necessary, higher values - and test between immersion heater terminals (L & N).
It should read about 19Ω (or 29Ω if only a 2000W element - unlikely).
If it reads around 10Ω this is the problem and you need a new one.

If it does read 19Ω (or 29&#937 then...
...repeat test between L & E - it should be open circuit (reading '1' (one)) but if it reads around 10Ω then this is the problem and you need a new one.

Also, test on all Ohms values.
If you read any value other than '1' then this is A problem and you need a new one.

 

[martinxxxxxx]

Competent electrician ........ is what im trying to avoid. i cant afford it.
?

Then it is easy for you.

IT IS THE ELEMENT

So you just need to go buy one and fit it.

Job Done

BTW The easy way to test it with no specialist equipment is to :- let it heat up for a couple of hours - it it trips - it is faulty.

 

[EFLImpudence]

Competent electrician ........ is what im trying to avoid. i cant afford it.

So you just need to go buy one and fit it.

.......................................

...................................


Joined: 19 Jul 2012
Posts: 5
Location: Argyll,
United Kingdom...................

 

[ban-all-sheds]

Now, now - play nicely.

 

[martinxxxxxx]

Competent electrician ........ is what im trying to avoid. i cant afford it.

So you just need to go buy one and fit it.

.......................................

...................................


Joined: 19 Jul 2012
Posts: 5
Location: Argyll,
United Kingdom...................

Well, I don't see a way that he can repair the one he has got, you can't put a plaster on it.
So he will have to buy one and a spanner and fit it. B&Q at Drumchapel will keep them for a tenner or so and a spanner for a fiver - Hope the OP lets us know how he got on. Some of the funniest stories are of the first time change over of these elements. I give them a swerve if I can - they can be tricky.

 

[tx200man]

i will, though i doubt ill travel 90 miles to get a spanner, have you ever heard of the internet, sometimes its useful.

 

[martinxxxxxx]

Let us know how you get on please, if you want and tips on this just holla and we all like photos on here - perhaps a before - during and after.

Also is you in a hard water area?