what could have caused my heated flooring timer switch to burn inside?

[scrummyyummy]

I have a problem with my switch that controls the heated flooring in my conservatory. To cut a long story short, this evening, there was a dreadful sort of peanut smell coming from the conservatory/kitchen and it seemed to be getting stronger. Hubby had gone out Christmas shopping (last minute as usual!) but I had to call him home as I was scared the house was going to catch fire. I didn't know where the smell was coming from and thought the boiler had gone off or I had left the cooker on. He came back and eventually found the source of the problem - the timer switch for the heated flooring. He was appalled at what he saw. The wires had melted inside and the smell was burning plastic. I've taken some photos which I want to post on here to ask if anyone can tell why it's caused this. We had an electrician put the flooring in about 4 or 5 years ago. If someone can perhaps offer some reason why the insides have burnt like it did. Would it have caused my house to catch fire if we didn't know? We're due to be away for a few days and if this had happened when we were away, I dread to think what we would have come back to. Thanks for any input.

Pictures:
http://i51.tinypic.com/nclahx.jpg
and
http://i51.tinypic.com/2sblmia.jpg

[AlBags]

Immersion heater elements can burn attachment terminals like this, usually due to a failing connection (resistance in the connection)
Looking at the burning, I would say the connections have become poor, resulting in heating of the conductors.
You need to have the resistance/continuity checked of the section concerned, and remake the connections properly if the check is ok.
My money is just on bad connections. Was probably fine when installed, and possibly poor design of connector block(s).

[pastafreak]

The electrician hubby of a friend of mine says that could only be caused by a loose connection in the connector thingy.

[scrummyyummy]

Thanks for your answers. I'll have to get an electrician in after Christmas now. Do you think it could have set fire to the house? Scary thought!

[AlBags]

No .. If installed correctly.

[scrummyyummy]

If it was installed properly, why would it have burnt inside like that after only 4 yrs and could it happen again? I'm still trying to get rid of that horrible burnt plastic smell!

[The Builder]

It does happen scrummy............ even if the unit is rated for the job. Not ideal is it?
Eventually, your circuit breaker or fuse, or your trip would have operated.
An electrician can easily check to see if the safety devices would have operated properly.

[AlBags]

I gave my opinion about the burnt connections in my first answer.
There may be a better quality/uprated terminal block available that can be used.
Best is to contact the manufacturer of the system first to check (with rating of system ready to hand)

[scrummyyummy]

Thanks Builder. So I shouldn't blame the electrician then? Should I just put it down to one of those things? You don't fancy popping over for a quick job do you?!

[The Builder]

................. love to Scrummy, but Al's probably nearer though ;o)

[scrummyyummy]

Thanks for your answer Al. If you're bored over Christmas, feel free to pop in with your tools!!
Have a great Christmas and New Year everyone and thanks for your help with this!

[AlBags]

Yes .. ok. There are always a few callouts cropping up .. usually central heating valves or outside electrics tripping mains boards!
Al.