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Hi all, just joined EF hoping to solve a problem. I live in a 3 year old flat in a block and my immersion heater stopped working. I have discovered the problem to be a burnt out switch (photo attached). As you can see it's pretty bad to the extent that the plastic has melted. My question is why should this happen, especially in a modern property? Cheers, Dave
Burnt out water heater switch IMG_20190304_181514 - EletriciansForums.net
 
Could be a number of things, poor connections, poor quality accessory who knows. Unfortunately modern day accessories are not the same quality of years past and a 13A fuse connection unit is not ideal for an immersion heater and you should replace it with a 20A double pole switch.
 
This really should never happen. Where did you get from, when and what's the make?
This is true but unfortunately modern day 13A fuse connection units whoever manufacturers then do not like being pushed to their limit. In the pic the fuse carrier part appears to have melted and this could purely down to a poor connection.
 
Thanks for the replies. I should say that I bought the property brand spanking new from one of the biggest developers in the country! So the switch is original! The wiring used in the photo is made up of strands.....is this ok or should it be a single core? Cheers, Dave
 
I assume they are the outgoing conductors so they should be okay but remove any damaged parts. Strip them back, fold over and ensure the terminal screw hits a good connection to them.
 
the outgoing cable will be stranded flex. looking at the offcuts in the pic. it's not been ferruled, which in itself is a recipe for burnt terminals. and as previous, a 20A D/P switch is preferable . overload protection should be 16A MCB in CU.
 
Hi all, just joined EF hoping to solve a problem. I live in a 3 year old flat in a block and my immersion heater stopped working. I have discovered the problem to be a burnt out switch (photo attached). As you can see it's pretty bad to the extent that the plastic has melted. My question is why should this happen, especially in a modern property? Cheers, Dave
View attachment 48159
Loose connection would be my diagnosis, Hercule is my middle name
 
Thanks for the replies. I should say that I bought the property brand spanking new from one of the biggest developers throw it up in a week as cheap as possible in the country! So the switch is original! The wiring used in the photo is made up of strands.....is this ok or should it be a single core? Cheers, Dave

corrected that for you.
 
Haha, get the point;) but nevertheless a 3 yr old property - this could have been a lot more serious than no hot water for a while! So basically can we say that stranded wire, folded over, (un-ferruled), tightened securely in a 13A D/P switch should be ok?
 
Hi DW and Welcome.
Unfortunately we do see these 13A fuse connection units that have been heat affected. Can you check if the circuit the FCU is on has a B16 rated mcb? I'm suspecting they've put yours off a 32A circuit and so felt they needed to fuse it down.
 
Haha, get the point;) but nevertheless a 3 yr old property - this could have been a lot more serious than no hot water for a while! So basically can we say that stranded wire, folded over, (un-ferruled), tightened securely in a 13A D/P switch should be ok?
yes. now the thread has been answered, here's a bit of culture:
 
You want to check a few of the other accessories for loose terminals and/or unearthed metal backboxes.

You wont get much comeback with the NHBC 10 year warranty, I'm afraid, but finding and rectifying any faults would make the property safer.

Average 3kW immersion/ 230v supply (nearer 240v in reality) gives you 12.5 to over 13Amps running current. The fuse was never going to last long.
Agree that it should have been a double pole switch without a fuse.
 
Does the Property have gas?
 
TI should say that I bought the property brand spanking new from one of the biggest developers in the country!
They tend to be the worst offenders for using cheap accessories, a few pence saved on a switch in your house turns into thousands saved on a large estate.

Also it is recommended that domestic properties get a periodic inspection every ten years to ensure the installation is still safe to use, not essential or the law but worthwhile.
 
Haha, get the point;) but nevertheless a 3 yr old property - this could have been a lot more serious than no hot water for a while! So basically can we say that stranded wire, folded over, (un-ferruled), tightened securely in a 13A D/P switch should be ok?

Get on to the to the sellers to sort that out .
It could have been a lot more serious .
Do not fix it yourself or you may jeopardise any future claims.
 

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