repair of soldering iron 8878D rework station (exploded ground trace)

[Sylvia]

I am pretty new to the world of electricity. Before I attempt to repair this soldering iron i want to find out why it happened.
I was just soldering and just at the moment where I put the iron in the stand, which is standing on my ESDmat, I heard a loud pop! And the circuit breaker cut out!
Coincidence? Or some sort of smps leakage thing?
When I got the iron(two month ago) I tested the tip continuity to ground, and got about 4ohms if I remember correctly. The wire on the picture is to measure continuity( my solder joints normally don't look like this but my other iron is faulty and doesn't get up to temperature). I measured again  continuity  between tip and earth plug and it beeps, so I think the first time I didn't apply enough pressure.
What I don't understand is how so much current has flown to vaporise the trace through the 1Mohm R in the mat, and where the difference of potential is coming from. The fuse in the soldering iron is not blown, but the breaker in the house cut off.
Even if I don't repair this one I what to understand what happened because when I buy a new one I have to know if a Transformer is better.
Has this some thing to do with smps?

[dial-a-monkey]

Exact same thing happened to me.. also the rectifier diodes blew up at some point - but it is for electronic repair

Does anyone know the specifications for the soldering ceramic element and hot air element?

I need to order replacements from Europe but don't have time to wait to get the part from China..

Is the soldering iron ceramic element is  1321? 1322? or or 1324?  ( i emailed the manufacturer Yagong but no reply)

it'a definitely 24 VAC measured with the power on, the length seems ~ 60 mm (but mine is broken)  x 3.8 mm diameter - I don't know the watts i thnk i read the specs as 60 watts but the 1321 ( most likely fit ) is 63 mm