Blown fuse -> liquid in plug?

[JohnElliott]

Not a question specific to vintage computers, but since it's in the world of electricity and power supplies I thought it might be worth posting here.

On unplugging a faulty model railway controller, I found that the 13A fuse in its mains plug looked blackened, and the interior of the plug was damp. There was also liquid on the earth pin of the plug, where it had a greenish colour, presumably from copper salts.

Any ideas where the liquid could have come from? The plug and controller have been in a warm, dry indoor environment for over 30 years. Were / are there such things as liquid-filled BS1362 fuses?

 

[vwestlife]

That's what I call "molded plug disease". The fuse blowing is coincidental. Fran Blanche did a video about it:

 

[Chuck(G)]

Could you perhaps have a leak in a wall or roof? Is there any plumbing installed in the same wall?

 

[JohnElliott]

That's what I call "molded plug disease". The fuse blowing is coincidental. Fran Blanche did a video about it:

That sounds likely - the flex is of about the right age, so it could have been quietly exuding the stuff into the plug for some time.

Could you perhaps have a leak in a wall or roof? Is there any plumbing installed in the same wall?

I don't think this is likely because the plug wasn't plugged directly into a wall, but into a multiway extension socket under a table.