Black box in old consumer unit - electrician stumped.

[alexkx3]

Thanks for the information guys. I've uploaded a photo under the hood.

 

[Richard Burns]

It certainly looks like a contactor and with nicely toasted terminals as well.

 

[alexkx3]

Good to know, what does a contractor do exactly and is it meant to buzz? Haha

 

[pirate]

No, it's a doorbell transformer that buzzes...

 

[Last plumber]

Thanks for the information guys. I've uploaded a photo under the hood.

View attachment 41500

I think it is a solenoid driven mercury tilt switch.
Be careful if it is, as you know Mercury is poisonous.
If you are going to dispose of them, they have to be treated as hazardous/poisonous waste.
Used for the same purpose to a contact set.
A control circuit operated the solenoid which in turn tilted the switch and the Mercury would make contact between two terminals in order to to carry a heavier load, e.g. Electric Underfloor Heating
The buzzing will likely be the solenoids.

 

[telectrix]

I think it is a solenoid driven mercury tilt switch.
Be careful if it is, as you know Mercury is poisonous.
If you are going to dispose of them, they have to be treated as hazardous/poisonous waste.
Used for the same purpose to a contact set.
A control circuit operated the solenoid which in turn tilted the switch and the Mercury would make contact between two terminals in order to to carry a heavier load, e.g. Electric Underfloor Heating

can't see mercury. the moon and maybe venus from bedroom window on a clear night perhaps.

 

[Last plumber]

can't see mercury. the moon and maybe venus from bedroom window on a clear night perhaps.

You sure that's not the reflection of your eyes in the glass?

 

[telectrix]

You sure that's not the reflection of your eyes in the glass?
View attachment 41501

how you got my crazy frog out the van.last time i saw him he was on my dashboard?

 

[Lucien Nunes]

OK so it is a mercury relay as I thought. It's perfectly safe if you don't smash it, just like a mercury thermometer, because it's sealed. The humming is not a problem, many AC relays hum when energised, often it means there's some dust or grit inside that is just stopping the armature fractionally short.

One of the load terminals has overheated - is the underfloor heating still going to be in use? If so, this should be repaired or replaced. If it does get replaced, I'll cover your costs to send it for the museum and then you don't have to think about disposal - you can't put it in normal refuse because it will get crushed and the mercury will escape.

 

[Last plumber]

Agreed - probably underfloor heating contactor or mercury relay. Unusual design, would be interested to see inside (the cover comes off with two knurled nuts). If it turns out to be something interesting, I'd pay to have it posted here for the museum!

Which Museum is this?