That is what is known as an "adaptable box" They have various uses hence the name. (They were also used as junction boxes for conduit) As for what it is or was used to connect to you guess first, why not open it and look?
Thanks - I have no idea where the other end of the cable is. It goes in under the worktop and behind a tiled wall. I think it was put in before the kitchen was done about 15-20 years ago. Possible to supply power to washer/dryer. The previous owner didnt know what it was so they used an extension/power strip from a plug socket above the worktop to supply the washing machine (something that I've continued to do).
Ideally the mystery live cable should be used to supply a new wall socket - but we plan to replace that bit of wall with patio doors in the near future - so not worth it. So just need to know if its OK to terminate the live cable in a smaller termination box , anything more complicated I'll call in an electrician so would need to line up some other jobs :)
Thanks for your advice and patience . By isolate you just mean switch off the mains feed temporarily whilst I'm putting on the smaller termination box or do you mean something more permanent (if the latter then i don't understand sorry!)
Since you do not know / have a means of local isolation, then you will have to turn the main switch of the consumers unit off, however, you should still check that the cable is dead, as the cable may be supplied from another source.
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